2008 Vol. 25, No. 2
2008, 25(2): 1-9.
Abstract:
Evolving for millions of years, the biomaterials of beetles have developed an optimized st ructure with
excellent mechanical performance, elaborate and rigid geomet ry shape and multifunctional surface texture, which makes it become one of the new object s in bionics. In this paper, the progress in bionic research was reviewed on the microst ructure of biomaterials, the mechanical performance, the functional morphology and the geomet ry shape in topology. The research status of biomaterials (including the beetle claw, the elyt ra and the wing) was summarized, also the problems existing in each work were discussed while the research emphases were prospected in future in the correlative area.
Evolving for millions of years, the biomaterials of beetles have developed an optimized st ructure with
excellent mechanical performance, elaborate and rigid geomet ry shape and multifunctional surface texture, which makes it become one of the new object s in bionics. In this paper, the progress in bionic research was reviewed on the microst ructure of biomaterials, the mechanical performance, the functional morphology and the geomet ry shape in topology. The research status of biomaterials (including the beetle claw, the elyt ra and the wing) was summarized, also the problems existing in each work were discussed while the research emphases were prospected in future in the correlative area.
2008, 25(2): 10-15.
Abstract:
C/ C2 Cu composites were fabricated by molten Cu alloy infilt ration into C/ C preforms prepared by chemical vapor infilt ration or impregnation/ carbonization. The t ribological behavior of the composite block with the Cu ring counterpart was evaluated using an MM22000 f riction and wear tester. The worn surface morphologies of
the composite blocks and the Cu rings were analyzed by means of scanning elect ron microscopy. The influence of the C/ C preform on the t ribological behavior of the composites was investigated. The result s show that the f riction coefficient , wear rate of the composites and the mass loss of Cu rings decrease with the increasing of density of the preforms ; the f riction coefficient and wear rate of the composite with impregnation/ carbonization preform is higher than those with chemical vapor infilt ration preform; the wear rate of the composites with parallel orientation is higher than that with vertical orientation , while the formers riction coefficient is lower .
C/ C2 Cu composites were fabricated by molten Cu alloy infilt ration into C/ C preforms prepared by chemical vapor infilt ration or impregnation/ carbonization. The t ribological behavior of the composite block with the Cu ring counterpart was evaluated using an MM22000 f riction and wear tester. The worn surface morphologies of
the composite blocks and the Cu rings were analyzed by means of scanning elect ron microscopy. The influence of the C/ C preform on the t ribological behavior of the composites was investigated. The result s show that the f riction coefficient , wear rate of the composites and the mass loss of Cu rings decrease with the increasing of density of the preforms ; the f riction coefficient and wear rate of the composite with impregnation/ carbonization preform is higher than those with chemical vapor infilt ration preform; the wear rate of the composites with parallel orientation is higher than that with vertical orientation , while the formers riction coefficient is lower .
2008, 25(2): 16-20.
Abstract:
The alloying effect s of 3 at %M ( M = Cr , Al , Ti) on the phase equlibria and eutectic morphology of
Nb220Si210Mo cast alloy were studied by SEM , EDS and XRD. All the studied alloys were prepared by arc
melting. The Nb220Si2 10Mo cast alloy contains niobium solid solution (Nb SS) andβNb 5Si 3two phases. A large volume f raction of lamellar eutectic (Nb SS 2βNb 5Si 3) appears in the microst ructure. The Cr additions change the phase relationship in Nb220Si210Mo cast alloy. A Laves phase of Cr 2Nb precipitates together with Nb SS,βNb 5Si 3in Nb220Si210Mo23Cr cast alloy , while no third phase was observed in 3 at %Al or 3 at %Ti added alloys. The Nb SS 2Nb 5Si 3 eutectic st ructure loses it s st raight lamellar characteristic in Cr doped alloy , whereas the lamellar characteristic of Nb SS 2Nb 5Si 3eutectic was enhanced by Al additions. The lamellar eutectic morphology changes to featheriness as a result of Ti additions. The lat tice parameters of Nb andβNb 5Si 3change with the alloying additions : The lat tice parameters of Nb decrease in all the alloys ; the c/ a value ofβNb 5Si 3 decreases in Nb220Si210Mo23Cralloy , while the c/ a value ofβNb 5Si 3 increases in the other three alloys.
The alloying effect s of 3 at %M ( M = Cr , Al , Ti) on the phase equlibria and eutectic morphology of
Nb220Si210Mo cast alloy were studied by SEM , EDS and XRD. All the studied alloys were prepared by arc
melting. The Nb220Si2 10Mo cast alloy contains niobium solid solution (Nb SS) andβNb 5Si 3two phases. A large volume f raction of lamellar eutectic (Nb SS 2βNb 5Si 3) appears in the microst ructure. The Cr additions change the phase relationship in Nb220Si210Mo cast alloy. A Laves phase of Cr 2Nb precipitates together with Nb SS,βNb 5Si 3in Nb220Si210Mo23Cr cast alloy , while no third phase was observed in 3 at %Al or 3 at %Ti added alloys. The Nb SS 2Nb 5Si 3 eutectic st ructure loses it s st raight lamellar characteristic in Cr doped alloy , whereas the lamellar characteristic of Nb SS 2Nb 5Si 3eutectic was enhanced by Al additions. The lamellar eutectic morphology changes to featheriness as a result of Ti additions. The lat tice parameters of Nb andβNb 5Si 3change with the alloying additions : The lat tice parameters of Nb decrease in all the alloys ; the c/ a value ofβNb 5Si 3 decreases in Nb220Si210Mo23Cralloy , while the c/ a value ofβNb 5Si 3 increases in the other three alloys.
2008, 25(2): 21-24.
Abstract:
In order to provide a theoretic direction for design of surface composites with high thermal fatigue performance , the thermal fatigue performance of WC/ iron mat rix surface composites obtained by the V2EPC casting
2 penet rating technology and mechanics of thermal fatigue crack formation and expansion in the composites were studied by the thermal shock test . The result s show that , with the increase of the volume f raction of WC particles ,the thermal fatigue performance of the composites increases until reaching the maximum when the volume f raction of WC particles is 52 %. The sample is undamaged af ter 10 times thermal cycling. The interaction of thermal st ress of WC particles and alternating pulsating st ress in the interface between WC particles and mat rices causes the thermal fatigue crack formation and expansion in the composites. The thermal fatigue performance of the composites can beimproved by using the ceramic particles with high heat conductivity as reinforcement , bet tering microscopic quality of the ceramic particles and selecting the mat rices with coefficient of thermal expansion closing that of the ceramic particles , and so on.
In order to provide a theoretic direction for design of surface composites with high thermal fatigue performance , the thermal fatigue performance of WC/ iron mat rix surface composites obtained by the V2EPC casting
2 penet rating technology and mechanics of thermal fatigue crack formation and expansion in the composites were studied by the thermal shock test . The result s show that , with the increase of the volume f raction of WC particles ,the thermal fatigue performance of the composites increases until reaching the maximum when the volume f raction of WC particles is 52 %. The sample is undamaged af ter 10 times thermal cycling. The interaction of thermal st ress of WC particles and alternating pulsating st ress in the interface between WC particles and mat rices causes the thermal fatigue crack formation and expansion in the composites. The thermal fatigue performance of the composites can beimproved by using the ceramic particles with high heat conductivity as reinforcement , bet tering microscopic quality of the ceramic particles and selecting the mat rices with coefficient of thermal expansion closing that of the ceramic particles , and so on.
2008, 25(2): 25-30.
Abstract:
W2Cu plasma facing gradient heat sink material was fabricated by the powder metallurgy technique.
The microst ructure and thermomechanical properties of W2Cu gradient material were studied. The composition has a graded dist ribution in the cross 2 section. The microst ructure around the interface changes continually through element diffusion at high temperature. And there is no obvious interface between different layers. Af ter sintering ,the copper forms a continuous network st ructure and dist ributes in the surrounding of tungsten particles. The chemical element dist ribution and thermomechanical properties of the W2 Cu gradient material have a graded- 1 dist ribution across the thickness. And it s whole thermal conductivity is 151. 4 W·(m·K) . The thermal shock and thermal cycle test s were conducted on the material under the condition of cooling temperature difference 800 ℃. Af ter the thermal shock test , no cracks were found at the interface. Cracks were observed af ter 83 thermal cycle test s , and the mechanism of crack formation was discussed.
W2Cu plasma facing gradient heat sink material was fabricated by the powder metallurgy technique.
The microst ructure and thermomechanical properties of W2Cu gradient material were studied. The composition has a graded dist ribution in the cross 2 section. The microst ructure around the interface changes continually through element diffusion at high temperature. And there is no obvious interface between different layers. Af ter sintering ,the copper forms a continuous network st ructure and dist ributes in the surrounding of tungsten particles. The chemical element dist ribution and thermomechanical properties of the W2 Cu gradient material have a graded- 1 dist ribution across the thickness. And it s whole thermal conductivity is 151. 4 W·(m·K) . The thermal shock and thermal cycle test s were conducted on the material under the condition of cooling temperature difference 800 ℃. Af ter the thermal shock test , no cracks were found at the interface. Cracks were observed af ter 83 thermal cycle test s , and the mechanism of crack formation was discussed.
2008, 25(2): 31-34.
Abstract:
The stiffness properties of t riaxially braided glass/ epoxy composites , considering the effect of braid
angle and specimen width , were tested. The differences between tensile and compressive stiffness properties were also discussed. The test result s show that the longitudinal modulus of the specimens decreases a lit tle with the increasing braid angle in the same fiber volume f raction , and so dose the Poisson ratio (when the braid angle is approximately greater than 35 degree) . As the specimen width changes f rom double to threefold the unit cell width , the stiffness properties of the specimen are almost equal . The longitudinal modulus and Poisson ratio are much greater than the t ransverse modulus and Poisson ratio. Furthermore , tensile specimens almost equal compressive specimens in modulus and Poisson ratio. It is found that the t ransverse tension and compression stress 2strain curves are highly nonlinear. The test result s can provide a reference for the braided composite st ructure design.
The stiffness properties of t riaxially braided glass/ epoxy composites , considering the effect of braid
angle and specimen width , were tested. The differences between tensile and compressive stiffness properties were also discussed. The test result s show that the longitudinal modulus of the specimens decreases a lit tle with the increasing braid angle in the same fiber volume f raction , and so dose the Poisson ratio (when the braid angle is approximately greater than 35 degree) . As the specimen width changes f rom double to threefold the unit cell width , the stiffness properties of the specimen are almost equal . The longitudinal modulus and Poisson ratio are much greater than the t ransverse modulus and Poisson ratio. Furthermore , tensile specimens almost equal compressive specimens in modulus and Poisson ratio. It is found that the t ransverse tension and compression stress 2strain curves are highly nonlinear. The test result s can provide a reference for the braided composite st ructure design.
2008, 25(2): 35-40.
Abstract:
U HMWPE/ LDPE composites were tested to collect acoustic emission (AE) signals under a quasi2static
tensile load. The unsupervised pat tern recognition ( PR) techniques were used to classify AE signals af ter their
preprocessing. Damage mechanisms in several specimens (0° 、90°and [ + 45° / - 45° ]) were investigated according to the classifying result s. The study shows that the PR technique is able to identify damage modes in the specimens such as mat rix cracking , fiber2mat rix debonding , fiber pullout , fiber breakage , etc. The identification result s are the same with the observation result s of the f racture surfaces of the specimens observed by a scanning elect ron microscope (SEM) . For U HMWPE/ LDPE composites , the characteristics of the AE signal are not affected by the type of specimen but are dependent on the failure mode. The PR technique can classify the AE signals issued f rom different modes effectively. By the cumulative AE hit s of each damage mode vs st rain curves , the damage process of the specimens can be reviewed clearly. Using the PR technique on AE signals gives nicety evidence for the damage mechanisms analysis of composites.
U HMWPE/ LDPE composites were tested to collect acoustic emission (AE) signals under a quasi2static
tensile load. The unsupervised pat tern recognition ( PR) techniques were used to classify AE signals af ter their
preprocessing. Damage mechanisms in several specimens (0° 、90°and [ + 45° / - 45° ]) were investigated according to the classifying result s. The study shows that the PR technique is able to identify damage modes in the specimens such as mat rix cracking , fiber2mat rix debonding , fiber pullout , fiber breakage , etc. The identification result s are the same with the observation result s of the f racture surfaces of the specimens observed by a scanning elect ron microscope (SEM) . For U HMWPE/ LDPE composites , the characteristics of the AE signal are not affected by the type of specimen but are dependent on the failure mode. The PR technique can classify the AE signals issued f rom different modes effectively. By the cumulative AE hit s of each damage mode vs st rain curves , the damage process of the specimens can be reviewed clearly. Using the PR technique on AE signals gives nicety evidence for the damage mechanisms analysis of composites.
2008, 25(2): 41-46.
Abstract:
The glass fiber/ epoxy resin 648 variable thickness laminates were prepared with the hot press and the
autoclave methods. The mechanism of defect formation in the two processings was investigated , and the effect s of the lay-up type and ply-drop gradient on the extent and dist ribution of defect s were studied. The result s show that fiber asymmet ric dist ribution , rich resin and delamination are the major types of defect s. Two dimensional resin flow result s in fiber uneven dist ribution , which is influenced by the fiber discontinuous area , permeability of the fiber bed and the uniformity of applied pressure. Rich resin result s f rom the fiber discontinuous area. Delamination has close relations with fiber dist ribution and anisot ropy in thermal expansion. The result s are valuable for eliminating the defect s and cont rolling the processing quality in variable thickness laminate st ructures.
The glass fiber/ epoxy resin 648 variable thickness laminates were prepared with the hot press and the
autoclave methods. The mechanism of defect formation in the two processings was investigated , and the effect s of the lay-up type and ply-drop gradient on the extent and dist ribution of defect s were studied. The result s show that fiber asymmet ric dist ribution , rich resin and delamination are the major types of defect s. Two dimensional resin flow result s in fiber uneven dist ribution , which is influenced by the fiber discontinuous area , permeability of the fiber bed and the uniformity of applied pressure. Rich resin result s f rom the fiber discontinuous area. Delamination has close relations with fiber dist ribution and anisot ropy in thermal expansion. The result s are valuable for eliminating the defect s and cont rolling the processing quality in variable thickness laminate st ructures.
2008, 25(2): 47-51.
Abstract:
Resin flow is the major mechanism affecting the fiber content , void content and laminate dimension during the hot pressing process. Based on the effective st ress principle and Darcy law , a mathematic model and the
corresponding finite element model were developed to simulate the resin flow and fiber compaction process. With the numerical simulation system , the fiber distribution can be predicted in the laminate. The effects of the temperature boundary and lay-up type of the fiber bed on the resin flow process were studied. It was found that the temperature boundary has a large influence on the numerical results while the lay-up type largely affect s the laminate thickness and fiber dist ribution. At the same time , it was validated that the accuracy of the boundary condition and material parameters impact s the reliability of the simulated results. For the T700S/ epoxy 5228 unidirectional laminates ,there was a good agreement between the numerical and experimental data.
Resin flow is the major mechanism affecting the fiber content , void content and laminate dimension during the hot pressing process. Based on the effective st ress principle and Darcy law , a mathematic model and the
corresponding finite element model were developed to simulate the resin flow and fiber compaction process. With the numerical simulation system , the fiber distribution can be predicted in the laminate. The effects of the temperature boundary and lay-up type of the fiber bed on the resin flow process were studied. It was found that the temperature boundary has a large influence on the numerical results while the lay-up type largely affect s the laminate thickness and fiber dist ribution. At the same time , it was validated that the accuracy of the boundary condition and material parameters impact s the reliability of the simulated results. For the T700S/ epoxy 5228 unidirectional laminates ,there was a good agreement between the numerical and experimental data.
2008, 25(2): 52-56.
Abstract:
An off-line measuring method of void formation conditions was designed based on the characteristics of
the hot press process for resin matrix composites and the mechanism of void formation cont rolled by diffusion. This method can quantitatively determine the relation between resin pressure and porosity. By means of this method , the effect s of gel temperature , relative moisture and resin pressure on void formation conditions in two epoxy systems were studied , including void content , morphology and distribution. The modified Kardos void model was compared with the experiment s. The result s indicate that the method can be used to simulate the void formation process caused by hygroscopic moisture in the hot press process , and it has good repeatability. The evolution of resin pressure vs porosity follows the exponential decay function. Moreover , the gel temperature and relative moisture have great effect s on porosity , while the resin type influences porosity , morphology and dist ribution of voids remarkably. The study provides an important measuring method and experimental evidence for void defect cont rol in composites during the hot press process.
An off-line measuring method of void formation conditions was designed based on the characteristics of
the hot press process for resin matrix composites and the mechanism of void formation cont rolled by diffusion. This method can quantitatively determine the relation between resin pressure and porosity. By means of this method , the effect s of gel temperature , relative moisture and resin pressure on void formation conditions in two epoxy systems were studied , including void content , morphology and distribution. The modified Kardos void model was compared with the experiment s. The result s indicate that the method can be used to simulate the void formation process caused by hygroscopic moisture in the hot press process , and it has good repeatability. The evolution of resin pressure vs porosity follows the exponential decay function. Moreover , the gel temperature and relative moisture have great effect s on porosity , while the resin type influences porosity , morphology and dist ribution of voids remarkably. The study provides an important measuring method and experimental evidence for void defect cont rol in composites during the hot press process.
Experimental study of the cocure process with the vacuum bag method for honeycomb sandwich structure
2008, 25(2): 57-62.
Abstract:
By using glass fiber/ epoxy 648 as panel and Nomex honeycomb as core , the effect s of resin flow behavior on the area of fillet and panel quality in the honeycomb sandwich st ructure were investigated with the vacuum bag cocure process , and the relationships between bonding st rength and fillet area were discussed by testing
the flatwise tensile st rength of samples. It is found that the fillet area first increases then decreases as the application time of vacuum is put off . The fillet area between bot tom panel and honeycomb core is larger than that between top panel and honeycomb core. As resin viscosity varies , the mechanisms of porosity elimination change , which can also be influenced by the dist ribution of gas passage in the sealed bag. Moreover , the result s of the mechanical test show that the improvement of flatwise tensile st rength can be achieved by increasing the fillet area. However , if the bonding st rength surpasses the tensile st rength of the honeycomb core , it has limitation to characterize the bonding property by the flatwise tensile st rength.
By using glass fiber/ epoxy 648 as panel and Nomex honeycomb as core , the effect s of resin flow behavior on the area of fillet and panel quality in the honeycomb sandwich st ructure were investigated with the vacuum bag cocure process , and the relationships between bonding st rength and fillet area were discussed by testing
the flatwise tensile st rength of samples. It is found that the fillet area first increases then decreases as the application time of vacuum is put off . The fillet area between bot tom panel and honeycomb core is larger than that between top panel and honeycomb core. As resin viscosity varies , the mechanisms of porosity elimination change , which can also be influenced by the dist ribution of gas passage in the sealed bag. Moreover , the result s of the mechanical test show that the improvement of flatwise tensile st rength can be achieved by increasing the fillet area. However , if the bonding st rength surpasses the tensile st rength of the honeycomb core , it has limitation to characterize the bonding property by the flatwise tensile st rength.
2008, 25(2): 63-67.
Abstract:
Flax noil fibers reinforced polylactide composites were prepared by means of flax noil fibers and polylactide fibers , non 2 woven method and moulding pressing technology. The effect s of carding times , volume
f raction of flax fibers and moulding temperature on tensile st rength of the composites were discussed respectively , and the tensile f racture surfaces and the adhesion were examined by scanning elect ron microscopy. The result s reveal that the tensile st rength reaches a peak at 190 ℃and volume f raction of 39. 6 %. The st rength increases first with the carding times and then decreases , which reaches the highest point af ter two carding times. The f racture surface reveals that the breakage property of the composite is brit tle , and the adhesion between flax fibers and the mat rix needs to be improved.
Flax noil fibers reinforced polylactide composites were prepared by means of flax noil fibers and polylactide fibers , non 2 woven method and moulding pressing technology. The effect s of carding times , volume
f raction of flax fibers and moulding temperature on tensile st rength of the composites were discussed respectively , and the tensile f racture surfaces and the adhesion were examined by scanning elect ron microscopy. The result s reveal that the tensile st rength reaches a peak at 190 ℃and volume f raction of 39. 6 %. The st rength increases first with the carding times and then decreases , which reaches the highest point af ter two carding times. The f racture surface reveals that the breakage property of the composite is brit tle , and the adhesion between flax fibers and the mat rix needs to be improved.
2008, 25(2): 68-73.
Abstract:
In order to discuss the relationship between the composite st ructure and acoustic insulation property ,
and explore a new approach to reduce the low -middle f requency noise , the composites with two different
arrangement s of glass fabric , vertical st ructure and laminated st ructure , in polyvinyl chloride resin were fabricated.The experiment s for acoustic insulation property were carried out in a reverberation-anechoic chambers measuring system. As a result , the arrangement of glass fabric has an obvious influence on the acoustic insulation property in the developed composites. When the thickness of the composites exceeds 5 mm under the same thickness and surface density , the composites with vertical fabric structure show the bet ter acoustic insulation property in low f requencies and low - middle f requencies than that with laminated fabric st ructure. The difference due to the vertical and laminated st ructures will become larger with the increase of sample thickness. Therefore , it is shown that changing the arrangement of the reinforcements can improve the acoustic insulation property of low f requencies and low-middle f requencies.
In order to discuss the relationship between the composite st ructure and acoustic insulation property ,
and explore a new approach to reduce the low -middle f requency noise , the composites with two different
arrangement s of glass fabric , vertical st ructure and laminated st ructure , in polyvinyl chloride resin were fabricated.The experiment s for acoustic insulation property were carried out in a reverberation-anechoic chambers measuring system. As a result , the arrangement of glass fabric has an obvious influence on the acoustic insulation property in the developed composites. When the thickness of the composites exceeds 5 mm under the same thickness and surface density , the composites with vertical fabric structure show the bet ter acoustic insulation property in low f requencies and low - middle f requencies than that with laminated fabric st ructure. The difference due to the vertical and laminated st ructures will become larger with the increase of sample thickness. Therefore , it is shown that changing the arrangement of the reinforcements can improve the acoustic insulation property of low f requencies and low-middle f requencies.
2008, 25(2): 74-79.
Abstract:
A sound insulation material was prepared using glass fabric/ PVC composite filled with steel-smelting
scoria powder . The relationship between the sound insulation performance and the surface density was analyzed by
the two-channel acoustic analyzer . Then the change of the sound reduction index was compared when the composite
was filled with the steel-smelting scoria or not . The dynamic mechanical property , the st ructural morphology and
the static mechanical property of composites were measured by DMA , SEM , universal material testing machine ,
etc. The result s showed : in low-middle frequencies (500～1000 Hz) , the sound insulation performance of the
composites was increased with increasing surface density , but variation of the sound insulation performance was not
obvious in high frequencies ( > 1000 Hz) . The sound insulation performance of the composites was enhanced in low
-middle frequencies (500～1000 Hz) , when filled with steel-smelting scoria powder . The steel-smelting scoria filler
had a certain influence on the damping behavior and mechanical property of the PVC sound insulation materials.
A sound insulation material was prepared using glass fabric/ PVC composite filled with steel-smelting
scoria powder . The relationship between the sound insulation performance and the surface density was analyzed by
the two-channel acoustic analyzer . Then the change of the sound reduction index was compared when the composite
was filled with the steel-smelting scoria or not . The dynamic mechanical property , the st ructural morphology and
the static mechanical property of composites were measured by DMA , SEM , universal material testing machine ,
etc. The result s showed : in low-middle frequencies (500～1000 Hz) , the sound insulation performance of the
composites was increased with increasing surface density , but variation of the sound insulation performance was not
obvious in high frequencies ( > 1000 Hz) . The sound insulation performance of the composites was enhanced in low
-middle frequencies (500～1000 Hz) , when filled with steel-smelting scoria powder . The steel-smelting scoria filler
had a certain influence on the damping behavior and mechanical property of the PVC sound insulation materials.
2008, 25(2): 80-86.
Abstract:
The artificial joint material of U HMWPE composite reinforced with coralline hydroxyapatite (CHA) in
different content s was prepared by the pressing formation method. A hip joint wear simulator was used to
investigate the biot ribological behavior of a CHA/ U HMWPE acetabular cup against a CoCrMo alloy femoral head in calf bovine synovia lubrication at 35 ℃±1 ℃. The experimental result s indicate that the addition of CHA powders to U HMWPE enhances the hardness of the composites , and decreases the wear rates under calf bovine synovia lubrication. When the addition of CHA powders is up to 20 wt % , CHA/ U HMWPE composites demonst rate the well designed performance of the hardness and biot ribological behaviors. The abrasive and fatigue wear are the main wear mechanisms for CHA/ U HMWPE composite cups. The sizes of the wear particles become larger with the increase of CHA powders addition.
The artificial joint material of U HMWPE composite reinforced with coralline hydroxyapatite (CHA) in
different content s was prepared by the pressing formation method. A hip joint wear simulator was used to
investigate the biot ribological behavior of a CHA/ U HMWPE acetabular cup against a CoCrMo alloy femoral head in calf bovine synovia lubrication at 35 ℃±1 ℃. The experimental result s indicate that the addition of CHA powders to U HMWPE enhances the hardness of the composites , and decreases the wear rates under calf bovine synovia lubrication. When the addition of CHA powders is up to 20 wt % , CHA/ U HMWPE composites demonst rate the well designed performance of the hardness and biot ribological behaviors. The abrasive and fatigue wear are the main wear mechanisms for CHA/ U HMWPE composite cups. The sizes of the wear particles become larger with the increase of CHA powders addition.
2008, 25(2): 87-93.
Abstract:
The 32D spacer fabric composite is a newly developed sandwich st ructure , which provides excellent
properties like out standing integrity , light weight , good designability , low manufacturing cost , and so on. The
fabric reinforcement with the hollow core is produced using the advanced textile technology , and the two surfaces are mechanically connected with continuous vertical plies. In this paper , the st ructural characters of 32D spacer fabric are analysed , the mechanical characteristics and damage modes of the 32D spacer fabric composite under flatwise compressive , shear , and three point s flexural loads are studied , and the effect s of st ructural parameters on the mechanical properties were investigated. The result s indicate that the compressive st rength and the shear st rength decrease , while the flexural stiffness increases with the increase of the pile height . The mechanical properties can be increased by raising the pile density. The result s cont ribute to the optimal design of 32D space fabrics.
The 32D spacer fabric composite is a newly developed sandwich st ructure , which provides excellent
properties like out standing integrity , light weight , good designability , low manufacturing cost , and so on. The
fabric reinforcement with the hollow core is produced using the advanced textile technology , and the two surfaces are mechanically connected with continuous vertical plies. In this paper , the st ructural characters of 32D spacer fabric are analysed , the mechanical characteristics and damage modes of the 32D spacer fabric composite under flatwise compressive , shear , and three point s flexural loads are studied , and the effect s of st ructural parameters on the mechanical properties were investigated. The result s indicate that the compressive st rength and the shear st rength decrease , while the flexural stiffness increases with the increase of the pile height . The mechanical properties can be increased by raising the pile density. The result s cont ribute to the optimal design of 32D space fabrics.
2008, 25(2): 94-100.
Abstract:
A multi2physics cure2thermal2st ress2flow field coupling numerical model was developed by the volume
averaging method for the hot2pressing processing , assuming that the prepregs are deformable porous medium. The fiber deformation , change of the volume f raction and permeability varied with the volume f raction of fiber were fully considered. A one 2 dimension curing model was developed and numerically solved by FEM for the composite laminate. AL E moving mesh method was used to t reat the moving boundary. The result shows that the model proposed here has bet ter agreement with experimental data than the classical models ; the composite laminate was compressed pile by pile. This phenomenon tallies with experiment . The quantity of resin discharged and the variety of volume f raction of fiber in different piles were revealed by this model .
A multi2physics cure2thermal2st ress2flow field coupling numerical model was developed by the volume
averaging method for the hot2pressing processing , assuming that the prepregs are deformable porous medium. The fiber deformation , change of the volume f raction and permeability varied with the volume f raction of fiber were fully considered. A one 2 dimension curing model was developed and numerically solved by FEM for the composite laminate. AL E moving mesh method was used to t reat the moving boundary. The result shows that the model proposed here has bet ter agreement with experimental data than the classical models ; the composite laminate was compressed pile by pile. This phenomenon tallies with experiment . The quantity of resin discharged and the variety of volume f raction of fiber in different piles were revealed by this model .
2008, 25(2): 101-108.
Abstract:
The mechanical and t ribological properties of carbon/ silicon carbide ( C/ SiC) brake materials were compared with those of carbon/ carbon (C/ C) ones. The result s show that the mechanical properties of C/ SiC brake
materials are higher than those of C/ C , and C/ SiC brake materials have overcome the disadvantages of C/ C such as low static f riction coefficient and insufficient stability of f riction coefficient caused by humidity. Therefore , C/ SiC is a new type of high performance brake materials. By analyzing the serving environmental characteristic of C/ C aircraf t braking materials , the optimizing design methods on the mechanical , thermo2physical properties , f riction and wear properties , materials st ructure and manufacture process of C/ SiC brake materials were discussed. It lays afoundation for realizing the co 2 design among materials?microst ructure , mechanical properties , f riction and wear properties.
The mechanical and t ribological properties of carbon/ silicon carbide ( C/ SiC) brake materials were compared with those of carbon/ carbon (C/ C) ones. The result s show that the mechanical properties of C/ SiC brake
materials are higher than those of C/ C , and C/ SiC brake materials have overcome the disadvantages of C/ C such as low static f riction coefficient and insufficient stability of f riction coefficient caused by humidity. Therefore , C/ SiC is a new type of high performance brake materials. By analyzing the serving environmental characteristic of C/ C aircraf t braking materials , the optimizing design methods on the mechanical , thermo2physical properties , f riction and wear properties , materials st ructure and manufacture process of C/ SiC brake materials were discussed. It lays afoundation for realizing the co 2 design among materials?microst ructure , mechanical properties , f riction and wear properties.
2008, 25(2): 109-114.
Abstract:
A unit cell model based on meso - structure and preparation procedure is presented for the in-plane
coefficient of thermal expansion (CTE) of 22D braided C/ SiC composites. In this unit cell model the actual st rand cross-2 section geometry and possible gap between two adjacent st rands are taken into account . The influence of st ructure parameters on the 22D braided C/ SiC composites?coefficient of thermal expansion was predicted. The predicted result s show that the composites?CTE increases with increase of kinking distance , but decreases with increase of fiber volume fraction and void volume f raction. The test result shows that there is a good correlation between the predicted result s and the experimental values.
A unit cell model based on meso - structure and preparation procedure is presented for the in-plane
coefficient of thermal expansion (CTE) of 22D braided C/ SiC composites. In this unit cell model the actual st rand cross-2 section geometry and possible gap between two adjacent st rands are taken into account . The influence of st ructure parameters on the 22D braided C/ SiC composites?coefficient of thermal expansion was predicted. The predicted result s show that the composites?CTE increases with increase of kinking distance , but decreases with increase of fiber volume fraction and void volume f raction. The test result shows that there is a good correlation between the predicted result s and the experimental values.
2008, 25(2): 115-122.
Abstract:
A thermo-mechanical model for ceramic materials subjected to thermal shock is presented in this paper .
The model was based on the thermo-mechanical coupling principle , and the statistical method was used to consider the heterogeneity of ceramics at the mesoscopic level , which is different f rom the previous models based on the so-called continuous damage mechanics. The failure process of plane ceramics subjected to thermal shock was investigated to validate this model and also to reveal the failure mechanism of ceramic materials under the thermal condition. The results show that the cracks are initiated ruleless on the surface where it is subjected to thermal shock at the beginning of the thermal shock. However , with the further thermal conduction some cracks gradually grow in the inner normal direction of the surface while the propagation of other cracks is rest rained. The results well agree with the experimental data. The proposed approach provides a new method to model the failure process of ceramic materials subjected to thermal shock.
A thermo-mechanical model for ceramic materials subjected to thermal shock is presented in this paper .
The model was based on the thermo-mechanical coupling principle , and the statistical method was used to consider the heterogeneity of ceramics at the mesoscopic level , which is different f rom the previous models based on the so-called continuous damage mechanics. The failure process of plane ceramics subjected to thermal shock was investigated to validate this model and also to reveal the failure mechanism of ceramic materials under the thermal condition. The results show that the cracks are initiated ruleless on the surface where it is subjected to thermal shock at the beginning of the thermal shock. However , with the further thermal conduction some cracks gradually grow in the inner normal direction of the surface while the propagation of other cracks is rest rained. The results well agree with the experimental data. The proposed approach provides a new method to model the failure process of ceramic materials subjected to thermal shock.
2008, 25(2): 123-128.
Abstract:
The highly ordered porous anodic alumina ( AAO) membrane was synthesized , and using it as
template , the WO 3 ·H 2O nanowire arrays with good orientation were prepared by the sol 2 gel method. The
product s are characterized by X2ray Diff raction and XPS , Scanning Elect ron Microscopy and Specific Surface Area Inst rument . And the result s show that WO 3 ·H 2O nanowires are uniformly dist ributed , and the diameters are consistent with the pores of the AAO template , about 26 nm in diameter and 1. 1μm in length. Compared with the WO 3·H 2O film on fiberglass cloth as carrier , the WO 3 ·H 2O nanowires have a smaller crystallite size , less density and larger specific surface area. Photocatalytic activities of the WO 3 ·H 2O/ AAO and WO 3 ·H 2O/fiberglass cloth were measured by degradation of gaseous formaldehyde respectively , and the rate constant of photocatalytic reaction is about 3. 4 times that of the WO 3·H 2O/ fiberglass cloth film. It is indicated that the WO 3 ·H 2O nanowires arrays synthesized as AAO template have higher photocatalytic activity.
The highly ordered porous anodic alumina ( AAO) membrane was synthesized , and using it as
template , the WO 3 ·H 2O nanowire arrays with good orientation were prepared by the sol 2 gel method. The
product s are characterized by X2ray Diff raction and XPS , Scanning Elect ron Microscopy and Specific Surface Area Inst rument . And the result s show that WO 3 ·H 2O nanowires are uniformly dist ributed , and the diameters are consistent with the pores of the AAO template , about 26 nm in diameter and 1. 1μm in length. Compared with the WO 3·H 2O film on fiberglass cloth as carrier , the WO 3 ·H 2O nanowires have a smaller crystallite size , less density and larger specific surface area. Photocatalytic activities of the WO 3 ·H 2O/ AAO and WO 3 ·H 2O/fiberglass cloth were measured by degradation of gaseous formaldehyde respectively , and the rate constant of photocatalytic reaction is about 3. 4 times that of the WO 3·H 2O/ fiberglass cloth film. It is indicated that the WO 3 ·H 2O nanowires arrays synthesized as AAO template have higher photocatalytic activity.
2008, 25(2): 129-134.
Abstract:
According to Tjiptobroto research , the multiple cracking failure mechanism of cementitious composites was studied based on the energy dissipation equilibrium criterion between the initial cracking and non2initial cracking. The partial debonding energy at non-initial cracking and the number of random effective fibers were
inserted with the assumption of the initial crack as the final failure crack of the st ructure. All the energy terms
related in the model were modified and simplified according to the properties of ult ra high performance cementitious composites (U HPCC) and a theoretical model of multiple cracking propagation of U HPCC was const ructed to predict the crack propagation based on energy equilibrium criterion. The number of cracks and energy dissipation terms of Tjiptobroto experiment specimens were predicted. The comparison with the test result s showed good agreement . It is suggested that the partial debonding energy term is necessary for U HPCC with high modulus of elasticity of steel fiber . The model can be a theoretical reference for predicting the initial cracking loading capacity and the ultimate limit loading capacity of U HPCC.
According to Tjiptobroto research , the multiple cracking failure mechanism of cementitious composites was studied based on the energy dissipation equilibrium criterion between the initial cracking and non2initial cracking. The partial debonding energy at non-initial cracking and the number of random effective fibers were
inserted with the assumption of the initial crack as the final failure crack of the st ructure. All the energy terms
related in the model were modified and simplified according to the properties of ult ra high performance cementitious composites (U HPCC) and a theoretical model of multiple cracking propagation of U HPCC was const ructed to predict the crack propagation based on energy equilibrium criterion. The number of cracks and energy dissipation terms of Tjiptobroto experiment specimens were predicted. The comparison with the test result s showed good agreement . It is suggested that the partial debonding energy term is necessary for U HPCC with high modulus of elasticity of steel fiber . The model can be a theoretical reference for predicting the initial cracking loading capacity and the ultimate limit loading capacity of U HPCC.
2008, 25(2): 135-142.
Abstract:
The dynamic mechanical properties of the concrete reinforced with various volume f ractions of basalt fiber subjected to high strain rates were studied using split Hopkinson pressure bar ( SHPB) apparatus , and the
validity of experiment was analyzed. The test s reveal that the dynamic st rength and toughness of basalt fiber
reinforced concrete ( BFRC) are st rain rate dependent , the st rain rate effect can be expressed by linear
approximations , and the relationship between dynamic st rength increase factor and logarithm of average strain rate is approximately linear . The addition of 0. 1 % (volume f raction) basalt fiber result s in 26 % and 14 % increase of impact compressive strength and toughness , respectively. The addition of 0. 2 % and 0. 3 % basalt fiber result s in 25 % increase of impact compressive st rength and no significant superiority in toughness to plain concrete. During μSHPB test s , BFRC specimens begin to fail at 123. 3～239. 45 s , nearly constant st rain rates are obtained over 62% of test durations , and the average relative error of the st rain rate is 23 % , so the SHPB test result s of BFRC are credible.
The dynamic mechanical properties of the concrete reinforced with various volume f ractions of basalt fiber subjected to high strain rates were studied using split Hopkinson pressure bar ( SHPB) apparatus , and the
validity of experiment was analyzed. The test s reveal that the dynamic st rength and toughness of basalt fiber
reinforced concrete ( BFRC) are st rain rate dependent , the st rain rate effect can be expressed by linear
approximations , and the relationship between dynamic st rength increase factor and logarithm of average strain rate is approximately linear . The addition of 0. 1 % (volume f raction) basalt fiber result s in 26 % and 14 % increase of impact compressive strength and toughness , respectively. The addition of 0. 2 % and 0. 3 % basalt fiber result s in 25 % increase of impact compressive st rength and no significant superiority in toughness to plain concrete. During μSHPB test s , BFRC specimens begin to fail at 123. 3～239. 45 s , nearly constant st rain rates are obtained over 62% of test durations , and the average relative error of the st rain rate is 23 % , so the SHPB test result s of BFRC are credible.
2008, 25(2): 143-148.
Abstract:
Based on the hypothesis of the rectangle and biconvex section shape of the yarn , and different collocations
between the inner warp and outer warp , thickness , section shape of the same st ructure being considered especially ,a geomet ric cell model for 2. 5D woven st ructures is developed. This model can be used to calculate the configuration of each yarn system , including the orientation angle of the constituent yarns and the fiber volume f raction. To verify the geomet ric model , 28 samples of 2. 5D woven composites with 8 various st ructures are selected and the fiber volume f raction is measured. The experiment result s are in good agreement with the outcomes of the model . Further , the geomet rical model is used to calculate and analyze the fiber volume f raction and oriental angle of three various structures. A conclusion is drawn that the interweaving times of the fiber in a cell is the important factor for the fiber volume f raction , and the tropism angle of the straight2joint structure?s warp is lower than the bend2joint structure?s.
Based on the hypothesis of the rectangle and biconvex section shape of the yarn , and different collocations
between the inner warp and outer warp , thickness , section shape of the same st ructure being considered especially ,a geomet ric cell model for 2. 5D woven st ructures is developed. This model can be used to calculate the configuration of each yarn system , including the orientation angle of the constituent yarns and the fiber volume f raction. To verify the geomet ric model , 28 samples of 2. 5D woven composites with 8 various st ructures are selected and the fiber volume f raction is measured. The experiment result s are in good agreement with the outcomes of the model . Further , the geomet rical model is used to calculate and analyze the fiber volume f raction and oriental angle of three various structures. A conclusion is drawn that the interweaving times of the fiber in a cell is the important factor for the fiber volume f raction , and the tropism angle of the straight2joint structure?s warp is lower than the bend2joint structure?s.
2008, 25(2): 149-155.
Abstract:
The effect of varying environmental conditions on the modal properties of composite laminates was
studied by experimental test s , which is vital for the safety of vibration2 based st ructural health monitoring (SHM)
and vibration cont rol techniques. The st ructure responses were measured with different temperature conditions by exciter and hammer test s. The modal parameters of composite laminates were identified by the Stochastic Subspace Identification (SSI) method. It is found that the f requencies and damping ratios have a st rong negative correlation with temperature , but no clear correlation of mode shapes with temperature changes can be observed. These experimental test result s indicate that the influence of temperature variation should be considered during the design process of st ructural health monitoring and vibration cont rol techniques in laminated composite engineering systems.
The effect of varying environmental conditions on the modal properties of composite laminates was
studied by experimental test s , which is vital for the safety of vibration2 based st ructural health monitoring (SHM)
and vibration cont rol techniques. The st ructure responses were measured with different temperature conditions by exciter and hammer test s. The modal parameters of composite laminates were identified by the Stochastic Subspace Identification (SSI) method. It is found that the f requencies and damping ratios have a st rong negative correlation with temperature , but no clear correlation of mode shapes with temperature changes can be observed. These experimental test result s indicate that the influence of temperature variation should be considered during the design process of st ructural health monitoring and vibration cont rol techniques in laminated composite engineering systems.
2008, 25(2): 156-160.
Abstract:
A three-phase model for the thermal expansion coefficient and t ransformation strain coefficient of the
shape memory alloy composite was developed , in which the composite was considered as the austenitic phase , the product phase ( martensite phase ) and the mat rix phase. The common expressions for the thermal expansion coefficient and t ransformation strain coefficient of the shape memory alloy composite were derived based on the micromechanical analysis. The expressions can be fit for fibers with various shapes. Compared with the t raditional method , non-linearity of shape memory alloy need not be considered. Not only was the method simple , but also the interaction among the three phases was considered. As an application of the model , the at tention was paid to the effects of the fiber geometry , various shapes and volume ratio of fibers in the composite on the effective thermal expansion coefficient and t ransformation strain coefficient of the composite. By comparing with references , it is shown that the results are credible. It is helpful to the design of intelligent composites.
A three-phase model for the thermal expansion coefficient and t ransformation strain coefficient of the
shape memory alloy composite was developed , in which the composite was considered as the austenitic phase , the product phase ( martensite phase ) and the mat rix phase. The common expressions for the thermal expansion coefficient and t ransformation strain coefficient of the shape memory alloy composite were derived based on the micromechanical analysis. The expressions can be fit for fibers with various shapes. Compared with the t raditional method , non-linearity of shape memory alloy need not be considered. Not only was the method simple , but also the interaction among the three phases was considered. As an application of the model , the at tention was paid to the effects of the fiber geometry , various shapes and volume ratio of fibers in the composite on the effective thermal expansion coefficient and t ransformation strain coefficient of the composite. By comparing with references , it is shown that the results are credible. It is helpful to the design of intelligent composites.
2008, 25(2): 161-165.
Abstract:
The tubular textile composite material was lined in the pipeline by inversion , as " pipe in pipeline" to rehabilitate the pipeline ; subjected to the inversion press and medium press , it s intensity affect s the rehabilitation
result . Adopting the correlative theories of material mechanics and engineering hydromechanics , an intact calculation formula to calculate the st ress during inversion and lining in pipeline was established , and taking the example of the repaired gas pipeline , the intensity in the axial and circle directions of the tubular textile composite material was designed. The result s show that the st ress in the axial direction is twice that in the circle direction ; and the st ress in the circle direction caused by the inversion press is related not only to the inversion press , but also to the inversion rate and temperature.
The tubular textile composite material was lined in the pipeline by inversion , as " pipe in pipeline" to rehabilitate the pipeline ; subjected to the inversion press and medium press , it s intensity affect s the rehabilitation
result . Adopting the correlative theories of material mechanics and engineering hydromechanics , an intact calculation formula to calculate the st ress during inversion and lining in pipeline was established , and taking the example of the repaired gas pipeline , the intensity in the axial and circle directions of the tubular textile composite material was designed. The result s show that the st ress in the axial direction is twice that in the circle direction ; and the st ress in the circle direction caused by the inversion press is related not only to the inversion press , but also to the inversion rate and temperature.
2008, 25(2): 166-172.
Abstract:
Based on the geomet ric nonlinear theory of the moderate-thick shallow spherical shells and the damage
theory , the constitutive relation for the laminated shallow spherical shells with mat rix damage and matrix-fiber shear damage was established by employing a st rain-based failure criterion. And a set of nonlinear equations of motion for the cross-plylaminated moderate-thick shallow spherical shells under the low velocity impact were derived. By using the orthogonal collocation point method and the Newmark method to discrete the unknown variable functions in space domain and in time domain respectively , the whole problem is solved by the iterative method synthetically. The numerical result s show that the damage , the initial velocity of the st riking object , and the shell geomet rical parameters all affect the contact force and the dynamic response of the st ructure under the low velocity impact to some extent .
Based on the geomet ric nonlinear theory of the moderate-thick shallow spherical shells and the damage
theory , the constitutive relation for the laminated shallow spherical shells with mat rix damage and matrix-fiber shear damage was established by employing a st rain-based failure criterion. And a set of nonlinear equations of motion for the cross-plylaminated moderate-thick shallow spherical shells under the low velocity impact were derived. By using the orthogonal collocation point method and the Newmark method to discrete the unknown variable functions in space domain and in time domain respectively , the whole problem is solved by the iterative method synthetically. The numerical result s show that the damage , the initial velocity of the st riking object , and the shell geomet rical parameters all affect the contact force and the dynamic response of the st ructure under the low velocity impact to some extent .
2008, 25(2): 173-177.
Abstract:
A numerical method was developed to study the delamination onset and growth characteristics during
the post-buckling process for the delaminated composite advanced isogrid stiffened plates subjected to a uniform axial compressive load. A finite element post -buckling analysis model was established based on the first -order shear deformation theory in conjunction with Von-Karman geomet rically nonlinear theory. The total energy release rate criterion combined with the virtual crack closure technique and the self-adaptive grid moving technology were used to analyze the delamination growth process , considering the contact effect of front contours of the delamination. By some numerical examples , the effect s of radius of delamination and rib stiffness upon the delamination growth process were discussed. Comparing the result s between the isogrid and the orthogrid stiffened plates with the same dimensions shows that the isogrid stiffened plate has good resistance ability against delamination onset and growth. The analysis method and conclusions provided in the paper would be valuable to estimate the load capability and optimal design for composite advanced grid stiffened st ructures.
A numerical method was developed to study the delamination onset and growth characteristics during
the post-buckling process for the delaminated composite advanced isogrid stiffened plates subjected to a uniform axial compressive load. A finite element post -buckling analysis model was established based on the first -order shear deformation theory in conjunction with Von-Karman geomet rically nonlinear theory. The total energy release rate criterion combined with the virtual crack closure technique and the self-adaptive grid moving technology were used to analyze the delamination growth process , considering the contact effect of front contours of the delamination. By some numerical examples , the effect s of radius of delamination and rib stiffness upon the delamination growth process were discussed. Comparing the result s between the isogrid and the orthogrid stiffened plates with the same dimensions shows that the isogrid stiffened plate has good resistance ability against delamination onset and growth. The analysis method and conclusions provided in the paper would be valuable to estimate the load capability and optimal design for composite advanced grid stiffened st ructures.
2008, 25(2): 178-187.
Abstract:
According to the finite element package ABAQUS , the buckling and postbuckling response of the doubly2curved composite shell under t ransverse loads was obtained by using the nonlinear finite element method. A
progressive failure model based on the Tsai2Wu failure criterion was int roduced in the finite element procedure to predict the initial failure and the progressive failure process. The effect of geomet ric parameters on the buckling and postbuckling response has been discussed in detail . The buckling and postbuckling of doubly2curved composite shells with stiffeners subjected to combined loads were simulated. The result s indicate that the shear load is helpful to the increase of the buckling loads.
According to the finite element package ABAQUS , the buckling and postbuckling response of the doubly2curved composite shell under t ransverse loads was obtained by using the nonlinear finite element method. A
progressive failure model based on the Tsai2Wu failure criterion was int roduced in the finite element procedure to predict the initial failure and the progressive failure process. The effect of geomet ric parameters on the buckling and postbuckling response has been discussed in detail . The buckling and postbuckling of doubly2curved composite shells with stiffeners subjected to combined loads were simulated. The result s indicate that the shear load is helpful to the increase of the buckling loads.
2008, 25(2): 188-193.
Abstract:
It is very difficult to build an exact model of composite lat tice st ructures in finite element analysis because of the complexity of the st ructure of the composite lat tice , so the homogenization of the lat tice st ructure is needed to obtain an equivalent elastic constant . The basic equation of elasticity of the lat tice st ructure was deduced
according to the principle of minimum potential energy and FEM , the elastic mat rix was given based on the
equivalent of virtual st rain energy , and the equivalent of density was got based on the equivalent of the kinetic
energy. The microscopic analysis of the cell element loaded with shear and extension was conducted , so the
equivalent elastic parameters were obtained by submit ting the equivalent parameter into the deduced equation , and then the macroscopic simulation result of the equivalent model was compared with the result of the exact model . It is verified that the method has a good precision and is appropriate for such kind of analysis in the engineering field.
It is very difficult to build an exact model of composite lat tice st ructures in finite element analysis because of the complexity of the st ructure of the composite lat tice , so the homogenization of the lat tice st ructure is needed to obtain an equivalent elastic constant . The basic equation of elasticity of the lat tice st ructure was deduced
according to the principle of minimum potential energy and FEM , the elastic mat rix was given based on the
equivalent of virtual st rain energy , and the equivalent of density was got based on the equivalent of the kinetic
energy. The microscopic analysis of the cell element loaded with shear and extension was conducted , so the
equivalent elastic parameters were obtained by submit ting the equivalent parameter into the deduced equation , and then the macroscopic simulation result of the equivalent model was compared with the result of the exact model . It is verified that the method has a good precision and is appropriate for such kind of analysis in the engineering field.
