2021 Vol. 38, No. 1
2021, 38(1): 1-15.
doi: 10.13801/j.cnki.fhclxb.20200909.003
Abstract:
Soft composites with liquid inclusions are a class of smart soft composites with functional fluid inclusions or phase-change inclusions. Owing to their excellent performances in deformability and functional designability, soft composites with liquid inclusions have been widely investigated and applied in the fields of flexible electronic devices, wearable devices and soft robots. This article reviews the latest research progress of soft composites with liquid inclusions from several aspects including the functional design and fabrication methods of soft composites with non-phase-change and phase-change liquid inclusions, the effective mechanical properties and size-dependent mechanical behaviors of soft composites with liquid inclusions, the challenges in current research of soft composites with liquid inclusions as well as the issues worthy of attention.
Soft composites with liquid inclusions are a class of smart soft composites with functional fluid inclusions or phase-change inclusions. Owing to their excellent performances in deformability and functional designability, soft composites with liquid inclusions have been widely investigated and applied in the fields of flexible electronic devices, wearable devices and soft robots. This article reviews the latest research progress of soft composites with liquid inclusions from several aspects including the functional design and fabrication methods of soft composites with non-phase-change and phase-change liquid inclusions, the effective mechanical properties and size-dependent mechanical behaviors of soft composites with liquid inclusions, the challenges in current research of soft composites with liquid inclusions as well as the issues worthy of attention.
2021, 38(1): 16-24.
doi: 10.13801/j.cnki.fhclxb.20200921.006
Abstract:
Composite materialization is an important trend in the structural upgrading of aerospace, defense, transportation, etc. Due to excellent mechanical properties and electrical conductivity, carbon fiber reinforced composites can be used in structural components whilst having the capacity to store/output electrical energy, which realize an integration of load bearing and electrical power charge/discharge. Hence, both the multifunctional material and the lightweight structure can be achieved using such carbon fibre composites. Structural power composites are comprised of carbon fiber electrodes, glass fiber separator and solid electrolytes, which are multifunctional polymer matrix transferreing load from reinforcments and enabling ions to travel between electrodes. This paper reviewed the typical structural power composites, including structural batteries, structural dielectric capacitors and structural supercapacitors. Constituent materials, device working principles and multifunctional characteristics were summarized for three types of structural power composites. The problems and challenges facing structural power composites were eventually dicussed. Insights were given for the development trend of structural power composites.
Composite materialization is an important trend in the structural upgrading of aerospace, defense, transportation, etc. Due to excellent mechanical properties and electrical conductivity, carbon fiber reinforced composites can be used in structural components whilst having the capacity to store/output electrical energy, which realize an integration of load bearing and electrical power charge/discharge. Hence, both the multifunctional material and the lightweight structure can be achieved using such carbon fibre composites. Structural power composites are comprised of carbon fiber electrodes, glass fiber separator and solid electrolytes, which are multifunctional polymer matrix transferreing load from reinforcments and enabling ions to travel between electrodes. This paper reviewed the typical structural power composites, including structural batteries, structural dielectric capacitors and structural supercapacitors. Constituent materials, device working principles and multifunctional characteristics were summarized for three types of structural power composites. The problems and challenges facing structural power composites were eventually dicussed. Insights were given for the development trend of structural power composites.
2021, 38(1): 25-35.
doi: 10.13801/j.cnki.fhclxb.20200921.004
Abstract:
Due to the exotic electromagnetic properties, metamaterial absorber has spawned extensive research into wave absorption materials over the past decade. This paper provides an introduction on metamaterial absorber by summarizing the reports in recent years. The metamaterial absorber has progressed significantly with special function from narrow bandwidth to broad bandwidth, wide angle tolerance, polarization independence and smart/tunable absorbance. Meanwhile the working frequency across the electromagnetic spectrum is broadened from microwave to terahertz, near-infrared and optical. This paper introduces different types of metamaterial absorber and summarizes the fabrication, design method and working principle of metamaterial absorber. Finally, the promising research field of metamaterial absorber is predicted.
Due to the exotic electromagnetic properties, metamaterial absorber has spawned extensive research into wave absorption materials over the past decade. This paper provides an introduction on metamaterial absorber by summarizing the reports in recent years. The metamaterial absorber has progressed significantly with special function from narrow bandwidth to broad bandwidth, wide angle tolerance, polarization independence and smart/tunable absorbance. Meanwhile the working frequency across the electromagnetic spectrum is broadened from microwave to terahertz, near-infrared and optical. This paper introduces different types of metamaterial absorber and summarizes the fabrication, design method and working principle of metamaterial absorber. Finally, the promising research field of metamaterial absorber is predicted.
2021, 38(1): 36-44.
doi: 10.13801/j.cnki.fhclxb.20200825.004
Abstract:
Glass fiber reinforced composites are widely used due to their low cost and good mechanical properties. Conductive glass fiber reinforced composites will further expand the application field of them, and be important direction of future development. This paper reviews the types, structures and properties of conductive glass fibers at home and abroad, and analyzes the effects of different conductive glass fibers on the properties of functional glass fiber composites. Finally, the development trend of polymer-based conductive glass fiber functional composites is discussed based on the current applications and limitations of conductive glass fiber and its composites.
Glass fiber reinforced composites are widely used due to their low cost and good mechanical properties. Conductive glass fiber reinforced composites will further expand the application field of them, and be important direction of future development. This paper reviews the types, structures and properties of conductive glass fibers at home and abroad, and analyzes the effects of different conductive glass fibers on the properties of functional glass fiber composites. Finally, the development trend of polymer-based conductive glass fiber functional composites is discussed based on the current applications and limitations of conductive glass fiber and its composites.
2021, 38(1): 45-54.
doi: 10.13801/j.cnki.fhclxb.20200921.005
Abstract:
Recent years, metal-organic frameworks (MOFs) and their derived nanostructures have made great progress in improving the volumetric expansion and the electronic conductivity of silicon anodes due to their high porosity, modifiable functional groups and controlled chemical components. Through discussing the latest research findings of MOFs and its derivatives in silicon anodes of lithium-ion batteries, the structural design of silicon anodes with MOFs as matrices was emphasized, and the related factors affecting its electrochemical properties were put forward. Finally, the research bottlenecks and possible development directions of MOFs and its derivatives in electrochemical properties were proposed.
Recent years, metal-organic frameworks (MOFs) and their derived nanostructures have made great progress in improving the volumetric expansion and the electronic conductivity of silicon anodes due to their high porosity, modifiable functional groups and controlled chemical components. Through discussing the latest research findings of MOFs and its derivatives in silicon anodes of lithium-ion batteries, the structural design of silicon anodes with MOFs as matrices was emphasized, and the related factors affecting its electrochemical properties were put forward. Finally, the research bottlenecks and possible development directions of MOFs and its derivatives in electrochemical properties were proposed.
2021, 38(1): 55-66.
doi: 10.13801/j.cnki.fhclxb.20200813.001
Abstract:
With the rapid development of urbanization and the increase of high-rise buildings, traditional fire-retardant materials are unable to meet the fire safety needs, additional fire warning system is required. However, today’s dominate commercial fire warning system is separated from building materials and thus need a long time to activate the alarm system, which wastes the best time for firefighting and evacuation. The key to realize super early fire warning is closely integrating the fire warning system and the matrix. Intelligent coating is a kind of artificial coating system that selectively provides the best response to external stimulus. By introducing intelligent coating into the traditional building fields, giving different kinds of materials flame retardant coating with fire-warning capabilities could make them actively respond to the external “fire” in the usage process, which would greatly improve the reliability of buildings, safety of life and their property safety as well. This paper summarizes and discusses the fire response mechanism, construction strategy and current research progress of flame retardant coating with fire-warning capabilities in recent years, and prospects future development and applications of this field.
With the rapid development of urbanization and the increase of high-rise buildings, traditional fire-retardant materials are unable to meet the fire safety needs, additional fire warning system is required. However, today’s dominate commercial fire warning system is separated from building materials and thus need a long time to activate the alarm system, which wastes the best time for firefighting and evacuation. The key to realize super early fire warning is closely integrating the fire warning system and the matrix. Intelligent coating is a kind of artificial coating system that selectively provides the best response to external stimulus. By introducing intelligent coating into the traditional building fields, giving different kinds of materials flame retardant coating with fire-warning capabilities could make them actively respond to the external “fire” in the usage process, which would greatly improve the reliability of buildings, safety of life and their property safety as well. This paper summarizes and discusses the fire response mechanism, construction strategy and current research progress of flame retardant coating with fire-warning capabilities in recent years, and prospects future development and applications of this field.
2021, 38(1): 67-83.
doi: 10.13801/j.cnki.fhclxb.20200922.002
Abstract:
Intelligent wearable field is a cross-research field with multiple disciplines and categories, and it has attracted the scholars’ attention from all domains in recent years. As the hub of intelligent wearable devices, the conductive fibers have a broad application prospect in this field because of their excellent mechanical properties and outstanding electrical and optical functional properties. In view of the research progress of conductive fibers which can be used in flexible smart wearable textiles, the conductive mechanism and preparation methods of conductive fibers including metal conductive fibers, conductive polymer fibers, carbon conductive fibers were systematically reviewed. Then the research progress and future application direction of composite conductive fibers prepared by different electrode materials in the past three years were described in details. Finally, the development prospect of this kind of flexible conductive fiber was summarized and prospected. It is expected to be helpful to the research and development of wearable intelligent fabric equipment and miniaturized flexible intelligent electronic products in the future.
Intelligent wearable field is a cross-research field with multiple disciplines and categories, and it has attracted the scholars’ attention from all domains in recent years. As the hub of intelligent wearable devices, the conductive fibers have a broad application prospect in this field because of their excellent mechanical properties and outstanding electrical and optical functional properties. In view of the research progress of conductive fibers which can be used in flexible smart wearable textiles, the conductive mechanism and preparation methods of conductive fibers including metal conductive fibers, conductive polymer fibers, carbon conductive fibers were systematically reviewed. Then the research progress and future application direction of composite conductive fibers prepared by different electrode materials in the past three years were described in details. Finally, the development prospect of this kind of flexible conductive fiber was summarized and prospected. It is expected to be helpful to the research and development of wearable intelligent fabric equipment and miniaturized flexible intelligent electronic products in the future.
2021, 38(1): 84-92.
doi: 10.13801/j.cnki.fhclxb.20200727.004
Abstract:
Flame retardant high density fiberboard (MPP-AP-WF/PR) composites were prepared with hot-pressing technology for wood-based products by adding melamine polyphosphate (MPP) and aluminium phosphate (AP) flame retardant to wood fiber/phenolic resin (WF/PR) composite. To investigate the optimum flame retardancy of the MPP-AP-WF/PR composites, the mass ratio of MPP to AP was explored. The effects of the mass ratio of MPP to AP on the mechanical properties, water resistance, thermal stability and flame retardancy of MPP-AP-WF/PR composites were studied based on the bending strength, thickness swelling rate, water absorption, thermogravimetic analysis and limiting oxygen index (LOI), and the flame retardant mechanism was also studied. The results show that the mechanical properties and water resistance of MPP-AP-WF/PR composites decrease significantly with the addition of flame retardant. However, the thermogravimetric results show that the flame retardant has no obvious effect on the initial heat resistance of MPP-AP-WF/PR composites, but the synergistic effect of both flame retardant at high temperature contributes to the carbon residue. LOI test results show that MPP has better flame retardant effect than AP when the flame retardant is used alone. Further, when MPP and AP are used together, the MPP-AP-WF/PR composite has the best flame retardant effect when the mass ratio of MPP to AP is 1∶2. It is due to both flame retardants exhibit the synergistic effect, which can promote the formation of dense char residue containing phosphoric acid compounds after the combustion of MPP-AP-WF/PR composite. The char can effectively prevent oxygen and heat from permeating into the internal carbon layer, thus improving the flame retardancy of the MPP-AP-WF/PR composite.
Flame retardant high density fiberboard (MPP-AP-WF/PR) composites were prepared with hot-pressing technology for wood-based products by adding melamine polyphosphate (MPP) and aluminium phosphate (AP) flame retardant to wood fiber/phenolic resin (WF/PR) composite. To investigate the optimum flame retardancy of the MPP-AP-WF/PR composites, the mass ratio of MPP to AP was explored. The effects of the mass ratio of MPP to AP on the mechanical properties, water resistance, thermal stability and flame retardancy of MPP-AP-WF/PR composites were studied based on the bending strength, thickness swelling rate, water absorption, thermogravimetic analysis and limiting oxygen index (LOI), and the flame retardant mechanism was also studied. The results show that the mechanical properties and water resistance of MPP-AP-WF/PR composites decrease significantly with the addition of flame retardant. However, the thermogravimetric results show that the flame retardant has no obvious effect on the initial heat resistance of MPP-AP-WF/PR composites, but the synergistic effect of both flame retardant at high temperature contributes to the carbon residue. LOI test results show that MPP has better flame retardant effect than AP when the flame retardant is used alone. Further, when MPP and AP are used together, the MPP-AP-WF/PR composite has the best flame retardant effect when the mass ratio of MPP to AP is 1∶2. It is due to both flame retardants exhibit the synergistic effect, which can promote the formation of dense char residue containing phosphoric acid compounds after the combustion of MPP-AP-WF/PR composite. The char can effectively prevent oxygen and heat from permeating into the internal carbon layer, thus improving the flame retardancy of the MPP-AP-WF/PR composite.
2021, 38(1): 93-101.
doi: 10.13801/j.cnki.fhclxb.20200720.001
Abstract:
In this study, hollow glass beads (HGB) were introduced into an aromatic thermosetting polyester (ATPE) based foam to prepare HGB/ATPE composite foam, and effect of content of HGB and foaming conditions on the properties of HGB/ATPE composite foam were investigated. After modification, the specific strength of the HGB/ATPE composite foam can reach 26.2 MPa/(g·cm−3), respectively. Moreover, the addition of HGB also greatly improves thermal properties and flame resistance performance of the HGB/ATPE composite foam. The thermal decomposition temperature, glass transition temperature and heat distortion temperature of the HGB/ATPE composite foam are 494.18℃, 230.47℃ and 191.00℃, respectively, and the limiting oxygen index can reach 35%–37%.
In this study, hollow glass beads (HGB) were introduced into an aromatic thermosetting polyester (ATPE) based foam to prepare HGB/ATPE composite foam, and effect of content of HGB and foaming conditions on the properties of HGB/ATPE composite foam were investigated. After modification, the specific strength of the HGB/ATPE composite foam can reach 26.2 MPa/(g·cm−3), respectively. Moreover, the addition of HGB also greatly improves thermal properties and flame resistance performance of the HGB/ATPE composite foam. The thermal decomposition temperature, glass transition temperature and heat distortion temperature of the HGB/ATPE composite foam are 494.18℃, 230.47℃ and 191.00℃, respectively, and the limiting oxygen index can reach 35%–37%.
2021, 38(1): 102-110.
doi: 10.13801/j.cnki.fhclxb.20200610.003
Abstract:
In order to improve the anti-friction and anti-wear properties of glass fiber/epoxy (GF/EP) composites, flexible MoO3 nanobelt-oxide carbon nanotubes film (m-MoO3-OCNTs) was prepared by the modified vacuum filtration technique, and m-MoO3-OCNTs modified GF/EP (m-MoO3-OCNTs-(GF/EP)) composites were prepared by vacuum assisted resin transfer molding (VARTM) process. The results show that m-MoO3-OCNTs can significantly improve the thermal conductivity and self-lubricating properties of the GF/EP composite. Under the dry friction test conditions, a high-quality continuous transfer film can be formed between the m-MoO3-OCNTs-(GF/EP) composites and the dual surface, which can effectively transfer the friction heat. Compared with the pure GF/EP composite, the friction and wear resistance of m-MoO3-OCNTs-(GF/EP) composite is improved by about 4 times.
In order to improve the anti-friction and anti-wear properties of glass fiber/epoxy (GF/EP) composites, flexible MoO3 nanobelt-oxide carbon nanotubes film (m-MoO3-OCNTs) was prepared by the modified vacuum filtration technique, and m-MoO3-OCNTs modified GF/EP (m-MoO3-OCNTs-(GF/EP)) composites were prepared by vacuum assisted resin transfer molding (VARTM) process. The results show that m-MoO3-OCNTs can significantly improve the thermal conductivity and self-lubricating properties of the GF/EP composite. Under the dry friction test conditions, a high-quality continuous transfer film can be formed between the m-MoO3-OCNTs-(GF/EP) composites and the dual surface, which can effectively transfer the friction heat. Compared with the pure GF/EP composite, the friction and wear resistance of m-MoO3-OCNTs-(GF/EP) composite is improved by about 4 times.
2021, 38(1): 111-119.
doi: 10.13801/j.cnki.fhclxb.20200519.002
Abstract:
Three kinds of polymer elastomer (PEO-PUEs) composites as cathode materials for anodic bonding were prepared via pre-polymerization method casted and cured at room temperature. The PEO-PUEs composites were characterized by good heat resistance that the 5% thermal decomposition temperatures Td,5% are higher than 250℃. The glass transition temperatures Tg are lower than −40℃ showing good flexibility. The PEO-PUEs composites have good mechanical properties. All PEO-PUEs composites have high ionic conductivity meeting the requirements of anodic bonding for cathode materials, and the highest value at 65℃ (the temperature required for anodic bonding) is reached to 1.50×10−3 S·cm−1 for PEO-PUEs composites (butane-1,4-diol (BDO) content is 50wt%, trimethylolpropane (TMP) content is 50wt% and SiO2 content is 1wt%). The anodic bonding by thermal guidance and dynamic field for polymer materials was designed, which was successfully used for jointing of PEO-PUEs composites with Al foil. When BDO content is 50wt%, TMP content is 50wt% and SiO2 content is 1wt%, the PEO-PUEs composites with Al foil have the best bonding performance, and the highest value of tensile strength can reach to 1.26 MPa. Compared with the traditional anodic bonding, the joint of PEO-PUEs composites with Al by anodic bonding designed with thermal guidance and dynamic field have a stable and dense intermediate bonding layer, and the peak current and bonding time are significantly improved, and the bonding interface strengthes are higher. This study provides some theoretical basis and reference experience for the practical application of anodic bonding in flexible packaging from the aspects of preparing polymer cathode materials and designing the corresponding anodic bonding process.
Three kinds of polymer elastomer (PEO-PUEs) composites as cathode materials for anodic bonding were prepared via pre-polymerization method casted and cured at room temperature. The PEO-PUEs composites were characterized by good heat resistance that the 5% thermal decomposition temperatures Td,5% are higher than 250℃. The glass transition temperatures Tg are lower than −40℃ showing good flexibility. The PEO-PUEs composites have good mechanical properties. All PEO-PUEs composites have high ionic conductivity meeting the requirements of anodic bonding for cathode materials, and the highest value at 65℃ (the temperature required for anodic bonding) is reached to 1.50×10−3 S·cm−1 for PEO-PUEs composites (butane-1,4-diol (BDO) content is 50wt%, trimethylolpropane (TMP) content is 50wt% and SiO2 content is 1wt%). The anodic bonding by thermal guidance and dynamic field for polymer materials was designed, which was successfully used for jointing of PEO-PUEs composites with Al foil. When BDO content is 50wt%, TMP content is 50wt% and SiO2 content is 1wt%, the PEO-PUEs composites with Al foil have the best bonding performance, and the highest value of tensile strength can reach to 1.26 MPa. Compared with the traditional anodic bonding, the joint of PEO-PUEs composites with Al by anodic bonding designed with thermal guidance and dynamic field have a stable and dense intermediate bonding layer, and the peak current and bonding time are significantly improved, and the bonding interface strengthes are higher. This study provides some theoretical basis and reference experience for the practical application of anodic bonding in flexible packaging from the aspects of preparing polymer cathode materials and designing the corresponding anodic bonding process.
2021, 38(1): 120-128.
doi: 10.13801/j.cnki.fhclxb.20200603.003
Abstract:
Halloysite nanotubes (HNTs) were compounded with 2-carboxyethyl phenylphosphonic acid (CEPPA) and used for modification of epoxy (EP) to prepare CEPPA-HNTs/EP composite. The effects of the ratios of CEPPA and HNTs on the thermal stability, flame retardancy and mechanical properties of the CEPPA-HNTs/EP composite were studied. TG analysis shows that the combination of CEPPA and HNTs can improve the thermal stability of the CEPPA-HNTs/EP composites, promote the carbonization and reduce the decomposition rate. The analyses of cone and limiting oxygen index show that adding HNTs can reduce the heat release rate, while CEPPA has a more significant effect on the increasing of oxygen index. The FTIR and SEM of the carbon residue show that the reaction of CEPPA and HNTs during the combustion produce silica-aluminate, which promotes the dehydration and cross-linking of the condensed phase. The analysis of mechanical properties shows that when mass ratio of HNTs to EP is 6%, mass ratio of CEPPA to EP is 4%, the tensile strength and impact strength of CEPPA-HNTs/EP composite are increased by 19.4% and 17.3%, respectively. SEM morphologies of impact sections of CEPPA-HNTs/EP composite show the characteristics of ductile fracture.
Halloysite nanotubes (HNTs) were compounded with 2-carboxyethyl phenylphosphonic acid (CEPPA) and used for modification of epoxy (EP) to prepare CEPPA-HNTs/EP composite. The effects of the ratios of CEPPA and HNTs on the thermal stability, flame retardancy and mechanical properties of the CEPPA-HNTs/EP composite were studied. TG analysis shows that the combination of CEPPA and HNTs can improve the thermal stability of the CEPPA-HNTs/EP composites, promote the carbonization and reduce the decomposition rate. The analyses of cone and limiting oxygen index show that adding HNTs can reduce the heat release rate, while CEPPA has a more significant effect on the increasing of oxygen index. The FTIR and SEM of the carbon residue show that the reaction of CEPPA and HNTs during the combustion produce silica-aluminate, which promotes the dehydration and cross-linking of the condensed phase. The analysis of mechanical properties shows that when mass ratio of HNTs to EP is 6%, mass ratio of CEPPA to EP is 4%, the tensile strength and impact strength of CEPPA-HNTs/EP composite are increased by 19.4% and 17.3%, respectively. SEM morphologies of impact sections of CEPPA-HNTs/EP composite show the characteristics of ductile fracture.
2021, 38(1): 129-136.
doi: 10.13801/j.cnki.fhclxb.20200619.001
Abstract:
The high silica fiber/ceramicizable phenolic resin composites were prepared by using AlB2 and SiC particles filled phenolic resin as matrix and high silica fiber as reinforcement. The effects of different amounts of AlB2 particles on the performance of high silica fiber/ceramicizable phenolic resin composites were studied at room temperature and after 1200℃ pyrolysis, respectively. The enhancement mechanism of AlB2 particles on pyrolysis products of the high silica fiber/ceramicizable phenolic resin composites was analyzed. The results reveal that as the amount of AlB2 particles increasing, the flexural strength of the high silica fiber/ceramicizable phenolic resin composites gradually decreases at room temperature, while the flexural strength of the 1200℃ pyrolytic composites displays a tendency to increase first and then decrease at high content of AlB2. When the mass ratio of AlB2 particles to phenolic resin is 12%, the flexural strength of the pyrolysis products is improved most significantly, 16.4% higher than that of the composites without AlB2 particles. AlB2 particles react in an aerobic environment at 1200℃ to form a co-melt composed of B2O3, Al2O3 and Al20B4O36, which fills the pores of the pyrolysis products of the phenolic resin, significantly reducing structural defects of the pyrolysis products, preventing further oxidation of the internal materials. Therefore, the mechanical properties of the pyrolysis products are improved.
The high silica fiber/ceramicizable phenolic resin composites were prepared by using AlB2 and SiC particles filled phenolic resin as matrix and high silica fiber as reinforcement. The effects of different amounts of AlB2 particles on the performance of high silica fiber/ceramicizable phenolic resin composites were studied at room temperature and after 1200℃ pyrolysis, respectively. The enhancement mechanism of AlB2 particles on pyrolysis products of the high silica fiber/ceramicizable phenolic resin composites was analyzed. The results reveal that as the amount of AlB2 particles increasing, the flexural strength of the high silica fiber/ceramicizable phenolic resin composites gradually decreases at room temperature, while the flexural strength of the 1200℃ pyrolytic composites displays a tendency to increase first and then decrease at high content of AlB2. When the mass ratio of AlB2 particles to phenolic resin is 12%, the flexural strength of the pyrolysis products is improved most significantly, 16.4% higher than that of the composites without AlB2 particles. AlB2 particles react in an aerobic environment at 1200℃ to form a co-melt composed of B2O3, Al2O3 and Al20B4O36, which fills the pores of the pyrolysis products of the phenolic resin, significantly reducing structural defects of the pyrolysis products, preventing further oxidation of the internal materials. Therefore, the mechanical properties of the pyrolysis products are improved.
2021, 38(1): 137-144.
doi: 10.13801/j.cnki.fhclxb.20200605.001
Abstract:
Graphene oxide (GO) was prepared by improved Hummers method and to obtain maleic anhydride (MAH)-GO by graft modification with MAH. 4,4’-diamino diphenyl methane bismaleimide (MBMI) resin as the reactive monomer, diallyl bisphenol A (BBA) and bisphenol A bisallyl ether (BBE) as reactive diluents, MBMI-BBA-BBE (MBAE) resin matrix was synthesized. The MAH-GO/MBAE composites were prepared by in-situ polymerization, the microstructure of MAH-GO was characterized and the effect of the reinforcement on mechanical properties of the MAH-GO/MBAE composites was studied. The results show that MAH is successfully grafted on the surface of GO, with clear lamellar structure and folds on the surface, and the graft rate is determined by chemical titration to be about 11.32%. The micromorphology of MAH-GO/MBAE composites shows that the fracture cracks are irregularly divergent and are typical ductile fracture, when MAH-GO is an appropriate amount and uniformly dispersed in the matrix resin. The impact strength and the bending strength of the MAH-GO/MBAE composite are 15.88 kJ/m2 and 142.13 MPa, which are 67.68% and 43.61% higher than that of the matrix resin, respectively, when the content of MAH-GO is 0.5wt%. The mechanical properties have been improved obviously.
Graphene oxide (GO) was prepared by improved Hummers method and to obtain maleic anhydride (MAH)-GO by graft modification with MAH. 4,4’-diamino diphenyl methane bismaleimide (MBMI) resin as the reactive monomer, diallyl bisphenol A (BBA) and bisphenol A bisallyl ether (BBE) as reactive diluents, MBMI-BBA-BBE (MBAE) resin matrix was synthesized. The MAH-GO/MBAE composites were prepared by in-situ polymerization, the microstructure of MAH-GO was characterized and the effect of the reinforcement on mechanical properties of the MAH-GO/MBAE composites was studied. The results show that MAH is successfully grafted on the surface of GO, with clear lamellar structure and folds on the surface, and the graft rate is determined by chemical titration to be about 11.32%. The micromorphology of MAH-GO/MBAE composites shows that the fracture cracks are irregularly divergent and are typical ductile fracture, when MAH-GO is an appropriate amount and uniformly dispersed in the matrix resin. The impact strength and the bending strength of the MAH-GO/MBAE composite are 15.88 kJ/m2 and 142.13 MPa, which are 67.68% and 43.61% higher than that of the matrix resin, respectively, when the content of MAH-GO is 0.5wt%. The mechanical properties have been improved obviously.
2021, 38(1): 145-154.
doi: 10.13801/j.cnki.fhclxb.20200824.003
Abstract:
Four kinds of glass fiber/epoxy vinyl ester resin (GF/EVER) composite laminates interlayer toughened by polyamide (PA), polyurethane (TPU), vinyl ester copolymer (EVA) and co-polyester (PEs) nonwoven fabrics were prepared by vacuum assisted resin infusion (VARI) process. The drop hammer impact test was carried out at temperature of 20℃, and the low-velocity impact response and impact resistance of the different GF/EVER composite laminates were compared and analyzed. The fracture mechanism was further studied by means of ultrasonic C-scan and SEM. The results indicate that the GF/EVER composite laminates modified by TPU and PEs nonwoven fabrics have better impact resistance through the comparison of impact damage area, dent depth, maximum contact force and residual compression strength (CAI). The interface phase and fiber binding degree of different non-woven fabrics and matrix resins are different. The impact damage mechanism of GF/EVER composite laminates is the cracking of matrix resin on the surface of impact surface, the delamination inside the composite laminate and the delamination cleavage or fiber fracture on the back of impact surface. Meanwhile, the low-velocity impact performance of GF/EVER composite laminates modified by TPU and PEs nonwoven fabrics was further studied under impact test at low temperature (−100℃, −45℃). The results show that the impact damage area will be increased and CAI will be decreased with the decrease of temperature. This may be the result of the combined action of the interlaminar residual thermal stress of GF/EVER composites and the embrittlement effect of matrix resin at low temperature.
Four kinds of glass fiber/epoxy vinyl ester resin (GF/EVER) composite laminates interlayer toughened by polyamide (PA), polyurethane (TPU), vinyl ester copolymer (EVA) and co-polyester (PEs) nonwoven fabrics were prepared by vacuum assisted resin infusion (VARI) process. The drop hammer impact test was carried out at temperature of 20℃, and the low-velocity impact response and impact resistance of the different GF/EVER composite laminates were compared and analyzed. The fracture mechanism was further studied by means of ultrasonic C-scan and SEM. The results indicate that the GF/EVER composite laminates modified by TPU and PEs nonwoven fabrics have better impact resistance through the comparison of impact damage area, dent depth, maximum contact force and residual compression strength (CAI). The interface phase and fiber binding degree of different non-woven fabrics and matrix resins are different. The impact damage mechanism of GF/EVER composite laminates is the cracking of matrix resin on the surface of impact surface, the delamination inside the composite laminate and the delamination cleavage or fiber fracture on the back of impact surface. Meanwhile, the low-velocity impact performance of GF/EVER composite laminates modified by TPU and PEs nonwoven fabrics was further studied under impact test at low temperature (−100℃, −45℃). The results show that the impact damage area will be increased and CAI will be decreased with the decrease of temperature. This may be the result of the combined action of the interlaminar residual thermal stress of GF/EVER composites and the embrittlement effect of matrix resin at low temperature.
2021, 38(1): 155-164.
doi: 10.13801/j.cnki.fhclxb.20200511.002
Abstract:
The poplar fiber/polyethylene composites with different contents of poplar fiber were prepared. The micromechanics of poplar fiber/polyethylene composites were modeled by Hirsch model, Kelly-Tyson model and Bowyer-Bader model. By studying the tensile stress-strain curves of the poplar fiber/polyethylene composite and plastic matrix and the length distribution of poplar fiber in the composite, the orientation coefficient, interfacial shear strength and intrinsic tensile strength of poplar fiber in polyethylene matrix were calculated, and the variation law of the tensile properties of poplar fiber/polyethylene composites was explained. In addition, the contribution ratio of subcritical fiber, supercritical fiber, plastic matrix to the tensile strength of poplar/polyethylene composites was obtained by using micromechanical model calculation.
The poplar fiber/polyethylene composites with different contents of poplar fiber were prepared. The micromechanics of poplar fiber/polyethylene composites were modeled by Hirsch model, Kelly-Tyson model and Bowyer-Bader model. By studying the tensile stress-strain curves of the poplar fiber/polyethylene composite and plastic matrix and the length distribution of poplar fiber in the composite, the orientation coefficient, interfacial shear strength and intrinsic tensile strength of poplar fiber in polyethylene matrix were calculated, and the variation law of the tensile properties of poplar fiber/polyethylene composites was explained. In addition, the contribution ratio of subcritical fiber, supercritical fiber, plastic matrix to the tensile strength of poplar/polyethylene composites was obtained by using micromechanical model calculation.
2021, 38(1): 165-176.
doi: 10.13801/j.cnki.fhclxb.20200922.003
Abstract:
The low velocity impact behavior of carbon fiber-glass fiber hybrid composites were investigated based on experimental and numerical simulation. Two finite element models of interlayer and intralayer hybrid composites under low velocity impact were established in ABAQUS software. The strain-based Hashin failure criteria was adopted to predict the intralaminar damage and zero thickness Cohesive elements were used to simulate the delamination. The progress damage process were carried out by user-defined subroutine VUMAT. Internal microscopic damage state and damage distribution condition were obtained by means of C-scan and Micro-CT technique. The results show that the interlayer hybrid structure composites provide better impact-resistant properties, while the I-C hybrid structure composites present the best impact behavior. The difference of impact response of hybrid structure composites is not obvious when the impact-side face is glass fiber. The impact property of CN-1 intralayer hybrid structure composites is better than that in CN-2 intralayer hybrid structure composites. The damage induced by low velocity impact includes the fiber broken near impact point, matrix damage and delamination. Hybrid structure can reduce impact damage effectively. The glass fiber layers in interlayer hybrid structure experienced severe damage and the hybrid interface have influence on the damage of intralayer laminates. The carbon fiber bundles provide protection effect on neighbor glass fiber bundle.
The low velocity impact behavior of carbon fiber-glass fiber hybrid composites were investigated based on experimental and numerical simulation. Two finite element models of interlayer and intralayer hybrid composites under low velocity impact were established in ABAQUS software. The strain-based Hashin failure criteria was adopted to predict the intralaminar damage and zero thickness Cohesive elements were used to simulate the delamination. The progress damage process were carried out by user-defined subroutine VUMAT. Internal microscopic damage state and damage distribution condition were obtained by means of C-scan and Micro-CT technique. The results show that the interlayer hybrid structure composites provide better impact-resistant properties, while the I-C hybrid structure composites present the best impact behavior. The difference of impact response of hybrid structure composites is not obvious when the impact-side face is glass fiber. The impact property of CN-1 intralayer hybrid structure composites is better than that in CN-2 intralayer hybrid structure composites. The damage induced by low velocity impact includes the fiber broken near impact point, matrix damage and delamination. Hybrid structure can reduce impact damage effectively. The glass fiber layers in interlayer hybrid structure experienced severe damage and the hybrid interface have influence on the damage of intralayer laminates. The carbon fiber bundles provide protection effect on neighbor glass fiber bundle.
2021, 38(1): 177-185.
doi: 10.13801/j.cnki.fhclxb.20200316.001
Abstract:
A digital image correlation (DIC) aided method combined with finite element model updating (FEMU) technique was proposed to identify the compressive constitutive parameters along the thickness direction for carbon fiber/epoxy (IM7/8552) orthotropic composite unidirectional laminate through short beam shear (SBS) test. The stress and strain distributions on the loading plane along the thickness direction under the loading nose were calculated by 3D finite element model (FEM) with the initial trial parameters. A cost function of the square difference between DIC-measured and FEM-calculated strains was given accordingly and unknown constitutive parameters were determined iteratively through minimization of it. The stress distribution is weakly sensitive to the constitutive parameters since the SBS test configuration is nearly statically determinate. Thus minimization of the cost function can be achieved by the least squared linear regression between FEM-calculated stress and DIC-measured strain. The advantages of the proposed method include that an explicit sensitivity matrix is not required in the iterative procedure, the efficiency of the parameter identification is high, and it is not sensitive to the initial trial parameters.
A digital image correlation (DIC) aided method combined with finite element model updating (FEMU) technique was proposed to identify the compressive constitutive parameters along the thickness direction for carbon fiber/epoxy (IM7/8552) orthotropic composite unidirectional laminate through short beam shear (SBS) test. The stress and strain distributions on the loading plane along the thickness direction under the loading nose were calculated by 3D finite element model (FEM) with the initial trial parameters. A cost function of the square difference between DIC-measured and FEM-calculated strains was given accordingly and unknown constitutive parameters were determined iteratively through minimization of it. The stress distribution is weakly sensitive to the constitutive parameters since the SBS test configuration is nearly statically determinate. Thus minimization of the cost function can be achieved by the least squared linear regression between FEM-calculated stress and DIC-measured strain. The advantages of the proposed method include that an explicit sensitivity matrix is not required in the iterative procedure, the efficiency of the parameter identification is high, and it is not sensitive to the initial trial parameters.
2021, 38(1): 186-197.
doi: 10.13801/j.cnki.fhclxb.20200603.001
Abstract:
For metal matrix composite materials, adding alloying elements is an effective way to improve its comprehensive performance. In the present study, the carbon nanotubes (CNTs) reinforced aluminum matrix (CNTs/Al-Si) composite foams with Si element were prepared by high-energy-ball milling and space holder method. Quasi-static compression test was carried out to study the compression properties and energy absorption performance of CNTs/Al-Si composite foams. The effects of sintering temperature and Si content on the microstructure, compression and energy absorption properties of the CNTs/Al-Si composite foams were further studied. The fracture failure mechanism was analyzed by the compression fracture morphology. The results show that the density and bonding of the CNTs/Al-Si composite foams increase with the increment of sintering temperature. When the sintering temperature is 600℃, mass fraction of Si is 7wt%, the yield strength, plateau stress, and energy absorption performance of CNTs/Al-Si composite foams are 98.4%, 167.7%, and 166.4% higher than that of the sintering temperature of 550℃, respectively. Moreover, the addition of Si element can refine composite powders during ball milling. Both of the strength and plasticity for the CNTs/Al-Si composite foams are improved after alloying. Compared with CNTs/Al composite foams, the yield strength and plateau stress of the CNTs/Al-Si composite foams with Si mass fraction of 7wt% increase by 58.5% and 117.8%, respectively. Meanwhile the energy absorption performance is significantly improved.
For metal matrix composite materials, adding alloying elements is an effective way to improve its comprehensive performance. In the present study, the carbon nanotubes (CNTs) reinforced aluminum matrix (CNTs/Al-Si) composite foams with Si element were prepared by high-energy-ball milling and space holder method. Quasi-static compression test was carried out to study the compression properties and energy absorption performance of CNTs/Al-Si composite foams. The effects of sintering temperature and Si content on the microstructure, compression and energy absorption properties of the CNTs/Al-Si composite foams were further studied. The fracture failure mechanism was analyzed by the compression fracture morphology. The results show that the density and bonding of the CNTs/Al-Si composite foams increase with the increment of sintering temperature. When the sintering temperature is 600℃, mass fraction of Si is 7wt%, the yield strength, plateau stress, and energy absorption performance of CNTs/Al-Si composite foams are 98.4%, 167.7%, and 166.4% higher than that of the sintering temperature of 550℃, respectively. Moreover, the addition of Si element can refine composite powders during ball milling. Both of the strength and plasticity for the CNTs/Al-Si composite foams are improved after alloying. Compared with CNTs/Al composite foams, the yield strength and plateau stress of the CNTs/Al-Si composite foams with Si mass fraction of 7wt% increase by 58.5% and 117.8%, respectively. Meanwhile the energy absorption performance is significantly improved.
2021, 38(1): 198-208.
doi: 10.13801/j.cnki.fhclxb.20200603.005
Abstract:
In industries such as aerospace, automobile, and petro-chemical, the composite overwrapped pressure vessels (COPV) have become a popular technique with the features of high stiffness-to-weight ratios and the advantages of leak-before-break. Based on the characteristics of filament winding process, a new technology of weldless connection of metal-lined COPV was proposed. The new technology used filament winding technology instead of welding forming process and designed a sealing groove on skirt length of the head to solve the problems of continuity and sealing between the head and the cylinder body. And an auxiliary forming tool was invented to apply filament winding process on this novel liner structure successfully. Then, the feasibility of the new structure was verified by hydraulic test. And the vessel could withstand the blasting design pressure about 110 MPa. Three damage modes were obtained by macroscopically inspecting of the vessel profile. Finally, based on a Chang-Chang failure criterion and the cohesive model, the finite element model of the novel structure was established by writing a user material subroutine VUMAT. The results show the delamination damage is the main damage mode and the fiber tensile fracture at the transition region of the head and cylinder is the main failure mode of the novel structure.
In industries such as aerospace, automobile, and petro-chemical, the composite overwrapped pressure vessels (COPV) have become a popular technique with the features of high stiffness-to-weight ratios and the advantages of leak-before-break. Based on the characteristics of filament winding process, a new technology of weldless connection of metal-lined COPV was proposed. The new technology used filament winding technology instead of welding forming process and designed a sealing groove on skirt length of the head to solve the problems of continuity and sealing between the head and the cylinder body. And an auxiliary forming tool was invented to apply filament winding process on this novel liner structure successfully. Then, the feasibility of the new structure was verified by hydraulic test. And the vessel could withstand the blasting design pressure about 110 MPa. Three damage modes were obtained by macroscopically inspecting of the vessel profile. Finally, based on a Chang-Chang failure criterion and the cohesive model, the finite element model of the novel structure was established by writing a user material subroutine VUMAT. The results show the delamination damage is the main damage mode and the fiber tensile fracture at the transition region of the head and cylinder is the main failure mode of the novel structure.
2021, 38(1): 209-220.
doi: 10.13801/j.cnki.fhclxb.20200622.004
Abstract:
WO3 nanorods were synthesized by hydrothermal method and WO3-Ag/graphitic C3N4 (g-C3N4) composite photocatalysts were synthesized by simple solvent evaporation and light deposition. The materials were characterized by XRD, SEM and TEM, et al. The results show that the WO3-Ag/g-C3N4 composite photocatalysts can expand the visible light response and effectively inhibit the photogenic electron and hole recombination due to the successful construction of Z-scheme heterojunction. Under the optimal conditions, the catalytic degradation efficiency of Rhodamine B (RhB) in 100 min is up to 96.8%, and the WO3-Ag/g-C3N4 composite photocatalysts have excellent stability. The photocatalytic mechanism indicates that the real active substances in photocatalytic experiments are hydroxyl radical and superoxide radical.
WO3 nanorods were synthesized by hydrothermal method and WO3-Ag/graphitic C3N4 (g-C3N4) composite photocatalysts were synthesized by simple solvent evaporation and light deposition. The materials were characterized by XRD, SEM and TEM, et al. The results show that the WO3-Ag/g-C3N4 composite photocatalysts can expand the visible light response and effectively inhibit the photogenic electron and hole recombination due to the successful construction of Z-scheme heterojunction. Under the optimal conditions, the catalytic degradation efficiency of Rhodamine B (RhB) in 100 min is up to 96.8%, and the WO3-Ag/g-C3N4 composite photocatalysts have excellent stability. The photocatalytic mechanism indicates that the real active substances in photocatalytic experiments are hydroxyl radical and superoxide radical.
2021, 38(1): 221-231.
doi: 10.13801/j.cnki.fhclxb.20200831.005
Abstract:
A polypyrrole/chitosan (PPy/CS) composite membrane was prepared using PPy and CS as raw materials, and the structure of the PPy/CS composite membrane was characterized by infrared, pore diameter analysis, thermal analysis and SEM. The effects of PPy/CS composite membrane on the adsorption performance and adsorption mechanism for Cu(Ⅱ) and Cr(Ⅵ) were discussed. The effects of pH value, adsorption time, and initial concentration of the solution on the adsorption efficiency were investigated. The results show that the adsorption efficiency of PPy/CS composite membrane for Cu(Ⅱ) and Cr(Ⅵ) are greater affected by the initial concentration of the solution. When pH=3.5, temperature is 333 K, the adsorption is shaken at 100 r·min−1 for 50 min, 20 mg of PPy/CS composite membrane adsorbs 6 mg·L−1 of Cu(Ⅱ) and Cr(Ⅵ), PPy/CS composite membrane for Cu(Ⅱ) shows good selectivity and adsorption amount reaches 2.715 mg·g−1; Compared with PPy/CS composite membrane and CS membrane, the adsorption rate of PPy/CS composite membrane for Cu(Ⅱ) increases to 94.14%; The PPy/CS composite membrane adsorbing Cu(Ⅱ) and Cr(Ⅵ) is desorbed and regenerated with 0.1 mol·L−1 NaOH solution. After circulation for 15 times, its adsorption amount changes very small, it can be used multiple times. The adsorption of Cu(Ⅱ) and Cr(Ⅵ) by PPy/CS composite membrane conforms to the pseudo-second-order kinetic model and Langmuir adsorption isotherm.
A polypyrrole/chitosan (PPy/CS) composite membrane was prepared using PPy and CS as raw materials, and the structure of the PPy/CS composite membrane was characterized by infrared, pore diameter analysis, thermal analysis and SEM. The effects of PPy/CS composite membrane on the adsorption performance and adsorption mechanism for Cu(Ⅱ) and Cr(Ⅵ) were discussed. The effects of pH value, adsorption time, and initial concentration of the solution on the adsorption efficiency were investigated. The results show that the adsorption efficiency of PPy/CS composite membrane for Cu(Ⅱ) and Cr(Ⅵ) are greater affected by the initial concentration of the solution. When pH=3.5, temperature is 333 K, the adsorption is shaken at 100 r·min−1 for 50 min, 20 mg of PPy/CS composite membrane adsorbs 6 mg·L−1 of Cu(Ⅱ) and Cr(Ⅵ), PPy/CS composite membrane for Cu(Ⅱ) shows good selectivity and adsorption amount reaches 2.715 mg·g−1; Compared with PPy/CS composite membrane and CS membrane, the adsorption rate of PPy/CS composite membrane for Cu(Ⅱ) increases to 94.14%; The PPy/CS composite membrane adsorbing Cu(Ⅱ) and Cr(Ⅵ) is desorbed and regenerated with 0.1 mol·L−1 NaOH solution. After circulation for 15 times, its adsorption amount changes very small, it can be used multiple times. The adsorption of Cu(Ⅱ) and Cr(Ⅵ) by PPy/CS composite membrane conforms to the pseudo-second-order kinetic model and Langmuir adsorption isotherm.
2021, 38(1): 232-238.
doi: 10.13801/j.cnki.fhclxb.20200513.002
Abstract:
The expandable graphite (EG) was microencapsulated by polyurea, and CuO was doped into the shell of the expandable graphite microcapsule (EG@PO) in order to improve the thermal conductivity of the shell. The microcapsules were characterized by SEM, thermogravimetric analysis and Fourier transform infrared spectroscopy. The effect of EG@PO and ammonium polyphosphate (APP) on the flame retardant properties of natural rubber (NR) was also investigated by limited oxygen index test, vertical burning test, thermogravimetric analysis, cone calorimeter test and thermal conductivity measurement. The results show that when mass of EG@PO is 6 g, the limited oxygen index of EG@PO/NR composite is 28.3%, and the vertical burning of composite reaches to V-0. The residual mass is 27.5% at 600℃. Furthermore, the heat release rate and total heat release of EG@PO/NR composites decrease dramatically to 467.7 kW/m2 and 48.4 MJ/m2, respectively, which is 49.8% and 25.7% lower than that of the pure NR. At the same time, the thermal conductivity of EG@PO/NR composites increases to 0.266 W/(m·K), because the CuO doped into the shell is beneficial to the heat transfer between the NR matrix and EG.
The expandable graphite (EG) was microencapsulated by polyurea, and CuO was doped into the shell of the expandable graphite microcapsule (EG@PO) in order to improve the thermal conductivity of the shell. The microcapsules were characterized by SEM, thermogravimetric analysis and Fourier transform infrared spectroscopy. The effect of EG@PO and ammonium polyphosphate (APP) on the flame retardant properties of natural rubber (NR) was also investigated by limited oxygen index test, vertical burning test, thermogravimetric analysis, cone calorimeter test and thermal conductivity measurement. The results show that when mass of EG@PO is 6 g, the limited oxygen index of EG@PO/NR composite is 28.3%, and the vertical burning of composite reaches to V-0. The residual mass is 27.5% at 600℃. Furthermore, the heat release rate and total heat release of EG@PO/NR composites decrease dramatically to 467.7 kW/m2 and 48.4 MJ/m2, respectively, which is 49.8% and 25.7% lower than that of the pure NR. At the same time, the thermal conductivity of EG@PO/NR composites increases to 0.266 W/(m·K), because the CuO doped into the shell is beneficial to the heat transfer between the NR matrix and EG.
2021, 38(1): 239-245.
doi: 10.13801/j.cnki.fhclxb.20200513.001
Abstract:
The temperature measurements and anti-/deicing experiments of the composite anti-/deicing component were performed with water-based and oil-based graphene coating. In view of the sensitivity of helicopter rotor to icing, a method of modifying the heat transfer performance of rotor anti-/deicing component with graphene coating on the iron surface was proposed to improve the efficiency of anti-/deicing component. In order to verify the effect of graphene coating on the heat transfer efficiency, the temperature measurements and deicing experiments of the coated rotor anti-/deicing components were carried out on the deicing experimental platform. The experimental results show that the graphene coating has a significant effect on improving the heat transfer performance of anti-/deicing component. Meanwhile, the heat transfer of oil-based graphene coating and water-based graphene coating were tested respectively. The results show that the temperature rise rate of oil-based graphene coating is higher than that of water-based graphene coating, and the average heat transfer rate of oil-based graphene coating is 0.021℃/s, the instantaneous maximum heat transfer rate is 0.083℃/s, which are higher than that of water-based graphene coating. The results indicate that the anti-/deicing effect of oil-based graphene coating is better than that of water-based graphene coating. Finally, by changing the spraying process to control the thickness of graphene coating, it is found that with the increasing of the thickness of graphene coating, the thermal conductivity of the coating gradually decreases. The experimental results verify the inverse proportion relationship between the thermal conductivity of graphene coating and the thickness of the sheet in the thermal conductivity formula deduced by Balandin et al.
The temperature measurements and anti-/deicing experiments of the composite anti-/deicing component were performed with water-based and oil-based graphene coating. In view of the sensitivity of helicopter rotor to icing, a method of modifying the heat transfer performance of rotor anti-/deicing component with graphene coating on the iron surface was proposed to improve the efficiency of anti-/deicing component. In order to verify the effect of graphene coating on the heat transfer efficiency, the temperature measurements and deicing experiments of the coated rotor anti-/deicing components were carried out on the deicing experimental platform. The experimental results show that the graphene coating has a significant effect on improving the heat transfer performance of anti-/deicing component. Meanwhile, the heat transfer of oil-based graphene coating and water-based graphene coating were tested respectively. The results show that the temperature rise rate of oil-based graphene coating is higher than that of water-based graphene coating, and the average heat transfer rate of oil-based graphene coating is 0.021℃/s, the instantaneous maximum heat transfer rate is 0.083℃/s, which are higher than that of water-based graphene coating. The results indicate that the anti-/deicing effect of oil-based graphene coating is better than that of water-based graphene coating. Finally, by changing the spraying process to control the thickness of graphene coating, it is found that with the increasing of the thickness of graphene coating, the thermal conductivity of the coating gradually decreases. The experimental results verify the inverse proportion relationship between the thermal conductivity of graphene coating and the thickness of the sheet in the thermal conductivity formula deduced by Balandin et al.
2021, 38(1): 246-254.
doi: 10.13801/j.cnki.fhclxb.20200617.004
Abstract:
In order to study the mechanical characteristics of reinforced composite pipe wound with steel strip for marine oil and gas transportation under complex loads, a numerical calculation model that considers non-linear contact was established. The model was studied to reflect the deformation and load-bearing properties of the composite pipe wound with steel strip under the combination of internal and external pressure, bending and tensile loads. The results show that the greater the pressure difference (the external pressure is greater than the internal one and ≤2 MPa), the more flexible the reinforced composite pipe wound with steel strip. Compared with pure bending, the additional combined effect of tensile load and pressure difference reduces the flexibility of reinforced composite pipe wound with steel strip. Compared with pure stretching, the additional combined effect of bending load and differential pressure reduces the tensile load carrying capacity of the reinforced composite pipe wound with steel strip. Compared with a single load, the location of the high stress area of the inner and outer polyethylene (PE) pipes and the symmetrical stress distribution path of the inner strip change under the complex loads. The greater the spiral angle and friction coefficient of the strip, the lower the flexibility of reinforced composite pipe wound with steel strip. The greater the friction coefficient, the higher the bearing capacity of reinforced composite pipe wound with steel strip. With the increase of the spiral angle under the combined bending load, the critical bending moment during buckling is non-monotonic and has a maximum value. The results can provide theoretical basis for the design, manufacture, and safety evaluation of reinforced composite pipe wound with steel strip.
In order to study the mechanical characteristics of reinforced composite pipe wound with steel strip for marine oil and gas transportation under complex loads, a numerical calculation model that considers non-linear contact was established. The model was studied to reflect the deformation and load-bearing properties of the composite pipe wound with steel strip under the combination of internal and external pressure, bending and tensile loads. The results show that the greater the pressure difference (the external pressure is greater than the internal one and ≤2 MPa), the more flexible the reinforced composite pipe wound with steel strip. Compared with pure bending, the additional combined effect of tensile load and pressure difference reduces the flexibility of reinforced composite pipe wound with steel strip. Compared with pure stretching, the additional combined effect of bending load and differential pressure reduces the tensile load carrying capacity of the reinforced composite pipe wound with steel strip. Compared with a single load, the location of the high stress area of the inner and outer polyethylene (PE) pipes and the symmetrical stress distribution path of the inner strip change under the complex loads. The greater the spiral angle and friction coefficient of the strip, the lower the flexibility of reinforced composite pipe wound with steel strip. The greater the friction coefficient, the higher the bearing capacity of reinforced composite pipe wound with steel strip. With the increase of the spiral angle under the combined bending load, the critical bending moment during buckling is non-monotonic and has a maximum value. The results can provide theoretical basis for the design, manufacture, and safety evaluation of reinforced composite pipe wound with steel strip.
2021, 38(1): 255-267.
doi: 10.13801/j.cnki.fhclxb.20200518.001
Abstract:
The early debonding damage of fiber reinforced polymer (FRP) composite strengthened concrete structure tends to be closed state, which can not be detected and located by traditional linear ultrasonic technology. Based on the continuous laser excited narrow-band ultrasonic technology combined with the nonlinear ultrasonic second harmonic method, a method of detecting the debonding damage of FRP composite strengthened concrete was proposed. This method uses intensity modulated laser technology to excite narrow-band ultrasonic surface wave on the surface of the reinforced structure. Under the ultrasonic disturbance, according to the contact nonlinear theory of the spring model, the debonding damage in the structure is in the boundary. The opening and closing effect will be produced on the surface, and the location of peel damage will be detected by acoustic nonlinear second harmonic response. Based on the results of simulation and experiment, the feasibility of this method for early debonding damage detection of FRP composite strengthened concrete structure was verified, and the non-contact and high sensitivity damage detection of FRP composite strengthened concrete structure was realized.
The early debonding damage of fiber reinforced polymer (FRP) composite strengthened concrete structure tends to be closed state, which can not be detected and located by traditional linear ultrasonic technology. Based on the continuous laser excited narrow-band ultrasonic technology combined with the nonlinear ultrasonic second harmonic method, a method of detecting the debonding damage of FRP composite strengthened concrete was proposed. This method uses intensity modulated laser technology to excite narrow-band ultrasonic surface wave on the surface of the reinforced structure. Under the ultrasonic disturbance, according to the contact nonlinear theory of the spring model, the debonding damage in the structure is in the boundary. The opening and closing effect will be produced on the surface, and the location of peel damage will be detected by acoustic nonlinear second harmonic response. Based on the results of simulation and experiment, the feasibility of this method for early debonding damage detection of FRP composite strengthened concrete structure was verified, and the non-contact and high sensitivity damage detection of FRP composite strengthened concrete structure was realized.
2021, 38(1): 268-278.
doi: 10.13801/j.cnki.fhclxb.20200507.004
Abstract:
For exploring the effect of continuously changed needle punched density during the needle punching process on the damage degree of the quartz woven fabrics and the fiber orientation distribution of quartz nonwoven felt in preform of the 3D needle punched composites, stereomicroscope was used to gather the pictures, which recorded the changes in the macro morphology with different needle punched densities, and an approach based on MATLAB software to characterize the damage degree of the quartz fabric woven was presented. Shimadzu AGS-250KNE universal testing machine was used to test the tensile property of the quartz woven fabrics under different needle punched densities. DHU-11 nonwoven felt orientation distribution testing machine was used for testing the fiber orientation distribution of the quartz nonwoven felts under different needle density values and angle range of 0°~180°. The results of the experiment indicate that the R value presenting to characterize damage degree of the quartz fabric woven is 0.518 when the needle punched density reaches 210 punches/cm2, which is approximately equal to the R value at 245 punches/cm2 (0.515). Therefore, it can be concluded that the damage degree of the quartz fabric woven has reached the limit when the needle-punched density reaches 210 punches/cm2. When the needle punched density is zero, the fiber orientation distribution of quartz nonwoven felt shows obvious normal distribution. The fiber orientation distribution amount within the angle range of 0°-15°, 165°-180° and 90° is bigger than that of other angle range under the same needle punched density. Moreover, the fiber orientation distribution amount under the same angle tends to decrease gradually with the increase of the needle needle punched density.
For exploring the effect of continuously changed needle punched density during the needle punching process on the damage degree of the quartz woven fabrics and the fiber orientation distribution of quartz nonwoven felt in preform of the 3D needle punched composites, stereomicroscope was used to gather the pictures, which recorded the changes in the macro morphology with different needle punched densities, and an approach based on MATLAB software to characterize the damage degree of the quartz fabric woven was presented. Shimadzu AGS-250KNE universal testing machine was used to test the tensile property of the quartz woven fabrics under different needle punched densities. DHU-11 nonwoven felt orientation distribution testing machine was used for testing the fiber orientation distribution of the quartz nonwoven felts under different needle density values and angle range of 0°~180°. The results of the experiment indicate that the R value presenting to characterize damage degree of the quartz fabric woven is 0.518 when the needle punched density reaches 210 punches/cm2, which is approximately equal to the R value at 245 punches/cm2 (0.515). Therefore, it can be concluded that the damage degree of the quartz fabric woven has reached the limit when the needle-punched density reaches 210 punches/cm2. When the needle punched density is zero, the fiber orientation distribution of quartz nonwoven felt shows obvious normal distribution. The fiber orientation distribution amount within the angle range of 0°-15°, 165°-180° and 90° is bigger than that of other angle range under the same needle punched density. Moreover, the fiber orientation distribution amount under the same angle tends to decrease gradually with the increase of the needle needle punched density.
2021, 38(1): 279-286.
doi: 10.13801/j.cnki.fhclxb.20200511.001
Abstract:
The macroscopic zero thermal expansion of material could be obtained through combining two kinds of materials with different positive thermal expansion coefficients within a unit cell. These composites usually possess higher thermally geometric stability in the large temperature fluctuation. However, it readily produces excessive thermal stress on the interface between the two constituent materials and therefore limits the allowable temperature range of the material. A new evaluation index of the maximum thermal stress of unit temperature rise was resorted to perform allowable temperature and stiffness analyses for the three types of typical bending-dominated zero expansion materials. Both the analytic and numerical simulation methods were adopted and the influences of cell design parameters on these aspects were also discussed. The results show that when the designed zero expansion attribute is achieved, the high stiffness and high allowable temperature range can be obtained at the same time if the reasonable constituent materials and structural parameters are selected.
The macroscopic zero thermal expansion of material could be obtained through combining two kinds of materials with different positive thermal expansion coefficients within a unit cell. These composites usually possess higher thermally geometric stability in the large temperature fluctuation. However, it readily produces excessive thermal stress on the interface between the two constituent materials and therefore limits the allowable temperature range of the material. A new evaluation index of the maximum thermal stress of unit temperature rise was resorted to perform allowable temperature and stiffness analyses for the three types of typical bending-dominated zero expansion materials. Both the analytic and numerical simulation methods were adopted and the influences of cell design parameters on these aspects were also discussed. The results show that when the designed zero expansion attribute is achieved, the high stiffness and high allowable temperature range can be obtained at the same time if the reasonable constituent materials and structural parameters are selected.
