A general approach for the modeling of fatigue induced damage in woven fabric composites and under multi-axial stress state is outlined in this paper. Guided by isotropic hardening/softening theories of plasticity and...A general approach for the modeling of fatigue induced damage in woven fabric composites and under multi-axial stress state is outlined in this paper. Guided by isotropic hardening/softening theories of plasticity and damage mechanics, a generalized bounding surface approach is presented. It is argued that the limit surface is only a special case in such a formulation when the fatigue cycle is set to one and that under fatigue environment the limit surface contracts to a failure (residual strength) state based on the number of cycle, stress path, and stress magnitude. Within the formulation, specific kinetic relations for microcrack growth are postulated for woven fabric composites and a new direction function is specified to capture strength anisotropy of the material. Anisotropic stiffness degradations and inelastic strain propagation due to damage processes are also obtained utilizing damage mechanics formulation. The paper concludes with comparing theoretical predictions against experimental records showing a good agreement.展开更多
A formulation for the prediction of the influence of various parameters on the elastic moduli of three-dimensional （3D） orthogonally woven composites has been given. These parameters can be classified into different...A formulation for the prediction of the influence of various parameters on the elastic moduli of three-dimensional （3D） orthogonally woven composites has been given. These parameters can be classified into different groups according to their properties, such as input design and material parameters, structural parameters etc. Some, by their nature, can be well controlled during the design and manufacture of the composite. The composite is assumed to be homogeneous and orthotropic macroscopically. With a selected representative unit cell and the stiffness model developed by author in 2000, the influence of all of these parameters can be determined. Results showing the influence of the main design geometric parameters are presented. They demonstrate that an optimal design is possible for the through-the-thickness stiffness of the composites. The methodology used can be generalized to predict the behavior of other kinds of 3D woven structures.展开更多
文摘A general approach for the modeling of fatigue induced damage in woven fabric composites and under multi-axial stress state is outlined in this paper. Guided by isotropic hardening/softening theories of plasticity and damage mechanics, a generalized bounding surface approach is presented. It is argued that the limit surface is only a special case in such a formulation when the fatigue cycle is set to one and that under fatigue environment the limit surface contracts to a failure (residual strength) state based on the number of cycle, stress path, and stress magnitude. Within the formulation, specific kinetic relations for microcrack growth are postulated for woven fabric composites and a new direction function is specified to capture strength anisotropy of the material. Anisotropic stiffness degradations and inelastic strain propagation due to damage processes are also obtained utilizing damage mechanics formulation. The paper concludes with comparing theoretical predictions against experimental records showing a good agreement.
基金the financial support from UK/China fellowships for Excellence programme(provided by the UK and China governments)the School of Civil Engineering,Hefei University of Technology,for administrative support in preparing this paper
文摘A formulation for the prediction of the influence of various parameters on the elastic moduli of three-dimensional （3D） orthogonally woven composites has been given. These parameters can be classified into different groups according to their properties, such as input design and material parameters, structural parameters etc. Some, by their nature, can be well controlled during the design and manufacture of the composite. The composite is assumed to be homogeneous and orthotropic macroscopically. With a selected representative unit cell and the stiffness model developed by author in 2000, the influence of all of these parameters can be determined. Results showing the influence of the main design geometric parameters are presented. They demonstrate that an optimal design is possible for the through-the-thickness stiffness of the composites. The methodology used can be generalized to predict the behavior of other kinds of 3D woven structures.
