1990 Vol. 7, No. 3
1990, 7(3): 1-8.
Abstract:
This paper presents the work of experimental optimization for tormutations of modified bismalcimidc resins.Experimental design used was a simplex gravity enter design which gives a good regression equation from a few experiments.Experimental results show that the regression equation is good enough for screening purpose.A perspective representation of response surfac,was put out,which visually demonstrates the relationship between the formulations and properties of the resins.Computer programs were used to assist in searching the optimum formulation.A new bismaleimide resin has been developed.It is processable and its properties are comparable with that of Narmco 5245C, an advanced bismaleimide resin developed in the eighties in USA.
This paper presents the work of experimental optimization for tormutations of modified bismalcimidc resins.Experimental design used was a simplex gravity enter design which gives a good regression equation from a few experiments.Experimental results show that the regression equation is good enough for screening purpose.A perspective representation of response surfac,was put out,which visually demonstrates the relationship between the formulations and properties of the resins.Computer programs were used to assist in searching the optimum formulation.A new bismaleimide resin has been developed.It is processable and its properties are comparable with that of Narmco 5245C, an advanced bismaleimide resin developed in the eighties in USA.
1990, 7(3): 9-16.
Abstract:
Composites fabricated from glass fabric stacking with thermoplastic PPS powder (powder technology) was evaluated.Flexural mechanical properties,dynamic mechanical characterization of GF/PPS processed under a variety of conditions are investigated.Scanning electron microscopy(SEM)was used to investigate the fiber/matrix penetration and fiber/resin interface adhesion.SFM analysis results indicated that the high level of mechanical properties exhibited by the thermoplastic PPS composite lanrinatus fabricated from powder technology can be attributed to the excellent fiber/matrix penetration and interfacial adhesion.Differences in the properties were observed as a function of processing conditions.
Composites fabricated from glass fabric stacking with thermoplastic PPS powder (powder technology) was evaluated.Flexural mechanical properties,dynamic mechanical characterization of GF/PPS processed under a variety of conditions are investigated.Scanning electron microscopy(SEM)was used to investigate the fiber/matrix penetration and fiber/resin interface adhesion.SFM analysis results indicated that the high level of mechanical properties exhibited by the thermoplastic PPS composite lanrinatus fabricated from powder technology can be attributed to the excellent fiber/matrix penetration and interfacial adhesion.Differences in the properties were observed as a function of processing conditions.
1990, 7(3): 17-25.
Abstract:
A review with 24 references on surface property modification of aromatic polyamides by cold plasma or some chemical means is given.In this review it has a discussion about the treatment effect and mechanism,the advantages and disadvantages of every means.At the last this review points out the perspective of this field.
A review with 24 references on surface property modification of aromatic polyamides by cold plasma or some chemical means is given.In this review it has a discussion about the treatment effect and mechanism,the advantages and disadvantages of every means.At the last this review points out the perspective of this field.
1990, 7(3): 27-33.
Abstract:
The relation of the effective thermal conductivity of particulate-reinforcad aluminium composite materials with the kind,size, volume fraction and distribution of particles in the composites was investigated in this work.
The relation of the effective thermal conductivity of particulate-reinforcad aluminium composite materials with the kind,size, volume fraction and distribution of particles in the composites was investigated in this work.
1990, 7(3): 35-41.
Abstract:
This paper studied the reasons of causing hystcresis loops and thermal strains of T300/LD3 when it is in thermal cycling.Experiment rosults indicated that the large plasticity of the matrix causes the thermal residual strains and hystcresis loops.It was also analyzed that the relations among the stress states of interfaces, the temperature ranges of thermal cycling and the thermal residual strains,A suggestion was put forward to improve the hystcresis and residual strain,which contains(1)minimizing the tomperaturc ranges of working environment of composites(2) making the matrix elastic under the working conditions and (3)incruasing the yiold stress of matrix.
This paper studied the reasons of causing hystcresis loops and thermal strains of T300/LD3 when it is in thermal cycling.Experiment rosults indicated that the large plasticity of the matrix causes the thermal residual strains and hystcresis loops.It was also analyzed that the relations among the stress states of interfaces, the temperature ranges of thermal cycling and the thermal residual strains,A suggestion was put forward to improve the hystcresis and residual strain,which contains(1)minimizing the tomperaturc ranges of working environment of composites(2) making the matrix elastic under the working conditions and (3)incruasing the yiold stress of matrix.
1990, 7(3): 43-49.
Abstract:
In this paper,a series of formulas for the jcodesic and the non-geodesic winding on a surface of revolutions are presented, which include the motion equations of winding machine,the formulas for calculating the winding angle and tha enveloping angle,the formulas for the design of the control cams and the chains distribution etc.On the basis of these formulas,the main content and the flow diagram of a computer programming is expounded.
In this paper,a series of formulas for the jcodesic and the non-geodesic winding on a surface of revolutions are presented, which include the motion equations of winding machine,the formulas for calculating the winding angle and tha enveloping angle,the formulas for the design of the control cams and the chains distribution etc.On the basis of these formulas,the main content and the flow diagram of a computer programming is expounded.
1990, 7(3): 51-59.
Abstract:
In this paper, the delamination solution of composite laminates,ortho-gonally and symmetrically stacked under axial tension is given.First of all,the eigen function expansions of strass and displacement fields, satisfying all of the basic equations,boundary conditions on crack surfaces and conditions of continuities between different plies are derived.Furthermore, the stress intensity factors as the coefficients of leading terms in the above expansions are determined by the generalized variational principle for multi-regions,to satisfy the boundary conditions.There are only line integrals in the variational equations due to the previous satisfaction of all basic Pquations.The computations shoe that this method of solution has the advantages of rapid convergency and time-saving.
In this paper, the delamination solution of composite laminates,ortho-gonally and symmetrically stacked under axial tension is given.First of all,the eigen function expansions of strass and displacement fields, satisfying all of the basic equations,boundary conditions on crack surfaces and conditions of continuities between different plies are derived.Furthermore, the stress intensity factors as the coefficients of leading terms in the above expansions are determined by the generalized variational principle for multi-regions,to satisfy the boundary conditions.There are only line integrals in the variational equations due to the previous satisfaction of all basic Pquations.The computations shoe that this method of solution has the advantages of rapid convergency and time-saving.
1990, 7(3): 61-68.
Abstract:
In this paper,a new finite element-Lagrangc degenerated shell hybrid/mixed element with 9 nodes is developed for the structural analysis of composite platesand shell.The element is based upon a modified Hellinger -Reissner principle,which has following advantages:high accuracy for evaluation of stresses and displacemens,elimination of redundant zero-energy deformation modes,apparently weakened locking effect and invariance with reference coordinates.Using this kind of element the efficiency in computation is improved as compared with other hybrid/mixed finite element and the transverse shear effect is taken into account.Several numerical exampies are presented.Numerical studies revea that the accurate and convergent solutions for fider-reinforced composi shallow and deep shells are obtined in comparison with that in references.
In this paper,a new finite element-Lagrangc degenerated shell hybrid/mixed element with 9 nodes is developed for the structural analysis of composite platesand shell.The element is based upon a modified Hellinger -Reissner principle,which has following advantages:high accuracy for evaluation of stresses and displacemens,elimination of redundant zero-energy deformation modes,apparently weakened locking effect and invariance with reference coordinates.Using this kind of element the efficiency in computation is improved as compared with other hybrid/mixed finite element and the transverse shear effect is taken into account.Several numerical exampies are presented.Numerical studies revea that the accurate and convergent solutions for fider-reinforced composi shallow and deep shells are obtined in comparison with that in references.
1990, 7(3): 69-74.
Abstract:
The fundamental solutions of the thin plate and plane problems are used to establish the integral equation which is solved by the numerical method. Cmpared with other approaches,this method has significant advantages [1]. In this paper, the anisotropic thin shallow shells are investigated. Numerical research shows that the accurate results are obtained with a relatively simple program.
The fundamental solutions of the thin plate and plane problems are used to establish the integral equation which is solved by the numerical method. Cmpared with other approaches,this method has significant advantages [1]. In this paper, the anisotropic thin shallow shells are investigated. Numerical research shows that the accurate results are obtained with a relatively simple program.
1990, 7(3): 75-81.
Abstract:
In this papas two kinds of elements,triangular laminated plate element with nine degree of freedom based on multi-variable quasi-conforming and penalty element technigue and laminated beam element with six degree of freedom are presented.Effects of transverrse shear deformation and rotational inertia are considered in these two elements.Free vibration, damping charactristic and transient response of stiffened composite plate are investigated by using finite clemenl method.Results obtainod are. valuable for the designs of stiffened composite,plates.
In this papas two kinds of elements,triangular laminated plate element with nine degree of freedom based on multi-variable quasi-conforming and penalty element technigue and laminated beam element with six degree of freedom are presented.Effects of transverrse shear deformation and rotational inertia are considered in these two elements.Free vibration, damping charactristic and transient response of stiffened composite plate are investigated by using finite clemenl method.Results obtainod are. valuable for the designs of stiffened composite,plates.
1990, 7(3): 83-90.
Abstract:
Stress distributions in single Pin-loaded Composite plates have been investigated by using a new method——Coating Moire lnterferometry,which was set up in Tianjing University.Moire Fringe patterns in the directions of 0°,45° and 90° have been obtained.Fixtures were improved in order to eliminate rigid body displacements produced in experiments.And the stiffness matrix to the specimen materials wero obtained through experiments and calculations.From the Moire fringes, distributions of strains and stresses were presented on horizontal sections through the centers of holes,vertical sections near holes and vertical symmetrical sections under the lower part of the holes. Six kinds of composite specimen, which consist of different fibers and layers,were investigated.Stress concentration factors near holes were also determined.Equations of equilibrium were checked to examine the precision of the experiments, and the reasons on experimental errors were explained. It is confirmed that Coating Moire Intarferometry cams be used in the determination of the stress distribution in Single Pin-Loaded Composite Plates.
Stress distributions in single Pin-loaded Composite plates have been investigated by using a new method——Coating Moire lnterferometry,which was set up in Tianjing University.Moire Fringe patterns in the directions of 0°,45° and 90° have been obtained.Fixtures were improved in order to eliminate rigid body displacements produced in experiments.And the stiffness matrix to the specimen materials wero obtained through experiments and calculations.From the Moire fringes, distributions of strains and stresses were presented on horizontal sections through the centers of holes,vertical sections near holes and vertical symmetrical sections under the lower part of the holes. Six kinds of composite specimen, which consist of different fibers and layers,were investigated.Stress concentration factors near holes were also determined.Equations of equilibrium were checked to examine the precision of the experiments, and the reasons on experimental errors were explained. It is confirmed that Coating Moire Intarferometry cams be used in the determination of the stress distribution in Single Pin-Loaded Composite Plates.
