In this paper, a combined viscoelasticity-viscoplasticity model, coupled with anisotropic damage and moisture effects, is developed for short fiber reinforced polymers (SFRPs) with different fiber contents and subject...In this paper, a combined viscoelasticity-viscoplasticity model, coupled with anisotropic damage and moisture effects, is developed for short fiber reinforced polymers (SFRPs) with different fiber contents and subjected to a variety of strain rates. In our model, a rate-dependent yield surface for the matrix phase is employed to identify initial yielding of the material. When an SFRP is loaded at small deformation before yielding, its viscoelastic behavior can be described using the generalized Maxwell model, while when plasticity occurs, a scalar internal state variable (ISV) is used to capture the hardening behavior caused by the polymeric constituent of the composite. The material degradation due to the moisture absorption of the composite is modeled by employing another type of ISV with different evolution equations. The complicated damage state of the SFRPs is captured by a second rank tensor, which is further decomposed to model the subscale damage mechanisms of micro-voids/cracks nucleation, growth and coalescence. It is concluded that the proposed constitutive model can be used to accurately describe complicated behaviors of SFRPs because the results predicted from the model are in good agreement with the experimental data.展开更多
In this work, we study an analytical procedure for evaluation of the displacement and stresses in fibre-reinforced anisotropic elastic media under effects of rotation and initial magnetic field, and due to the applica...In this work, we study an analytical procedure for evaluation of the displacement and stresses in fibre-reinforced anisotropic elastic media under effects of rotation and initial magnetic field, and due to the application of the rotation and initial magnetic field. Effects of rotation and initial magnetic field are analyzed theoretically and computed numerically. Numerical results have been given and illustrated graphically. Comparison was made with the results obtained in the presence of rotation and initial magnetic field in fibre-reinforced anisotropic and isotropic elastic media. The results indicate the effect of rotation and initial magnetic field.展开更多
基体开裂、纤维拔出、界面剥离等是碳纤维增强复合材料常出现的局部各向异性损伤现象,这些损伤逐渐扩展,削弱了材料的强度和刚度,影响材料的承载能力。对此利用宏微观摄动理论对位移进行双范围渐进展开,在微观位移中引入损伤应变,通过...基体开裂、纤维拔出、界面剥离等是碳纤维增强复合材料常出现的局部各向异性损伤现象,这些损伤逐渐扩展,削弱了材料的强度和刚度,影响材料的承载能力。对此利用宏微观摄动理论对位移进行双范围渐进展开,在微观位移中引入损伤应变,通过计算损伤应变集中因子,得到了含损伤的均质化损伤弹性常数(宏观有效刚度矩阵),用平均法和混合法检验了无损情况均质化弹性常数计算的有效性。利用经典的热动力学理论建立了相应的损伤演化方程,结合有限元法得到不同铺层方式的宏观应力-应变关系以及各向异性损伤的演化规律,所得结果与Wang等人(Wang S Z,Journal of Materials Science,1992,27:5483-5496)用相同材料做出的实验数据较为吻合,证明了利用宏微观双范围渐进展开方法分析包含各向异性损伤情况碳纤维增强复合材料力学性质的有效性。展开更多
Steel wire wound reinforced flexible pipe in this study mainly consists of multiple anisotropic steel wire wound reinforcement layers and multiple isotropic rubber layers.Based on 3D anisotropic elastic theory,the ana...Steel wire wound reinforced flexible pipe in this study mainly consists of multiple anisotropic steel wire wound reinforcement layers and multiple isotropic rubber layers.Based on 3D anisotropic elastic theory,the analytic solutions of stresses and elastic deformations of steel wire wound reinforced rubber flexible pipe under internal pressure are presented.As the adjacent reinforcement layers with wound angle have different radii,the single reinforcement layer shows the effect of tensile-shear coupling.Moreover,the static loading test results of steel wire wound reinforced rubber flexible pipe under internal pressure are basically coincided with the calculated values by present method.展开更多
文摘In this paper, a combined viscoelasticity-viscoplasticity model, coupled with anisotropic damage and moisture effects, is developed for short fiber reinforced polymers (SFRPs) with different fiber contents and subjected to a variety of strain rates. In our model, a rate-dependent yield surface for the matrix phase is employed to identify initial yielding of the material. When an SFRP is loaded at small deformation before yielding, its viscoelastic behavior can be described using the generalized Maxwell model, while when plasticity occurs, a scalar internal state variable (ISV) is used to capture the hardening behavior caused by the polymeric constituent of the composite. The material degradation due to the moisture absorption of the composite is modeled by employing another type of ISV with different evolution equations. The complicated damage state of the SFRPs is captured by a second rank tensor, which is further decomposed to model the subscale damage mechanisms of micro-voids/cracks nucleation, growth and coalescence. It is concluded that the proposed constitutive model can be used to accurately describe complicated behaviors of SFRPs because the results predicted from the model are in good agreement with the experimental data.
文摘In this work, we study an analytical procedure for evaluation of the displacement and stresses in fibre-reinforced anisotropic elastic media under effects of rotation and initial magnetic field, and due to the application of the rotation and initial magnetic field. Effects of rotation and initial magnetic field are analyzed theoretically and computed numerically. Numerical results have been given and illustrated graphically. Comparison was made with the results obtained in the presence of rotation and initial magnetic field in fibre-reinforced anisotropic and isotropic elastic media. The results indicate the effect of rotation and initial magnetic field.
文摘基体开裂、纤维拔出、界面剥离等是碳纤维增强复合材料常出现的局部各向异性损伤现象,这些损伤逐渐扩展,削弱了材料的强度和刚度,影响材料的承载能力。对此利用宏微观摄动理论对位移进行双范围渐进展开,在微观位移中引入损伤应变,通过计算损伤应变集中因子,得到了含损伤的均质化损伤弹性常数(宏观有效刚度矩阵),用平均法和混合法检验了无损情况均质化弹性常数计算的有效性。利用经典的热动力学理论建立了相应的损伤演化方程,结合有限元法得到不同铺层方式的宏观应力-应变关系以及各向异性损伤的演化规律,所得结果与Wang等人(Wang S Z,Journal of Materials Science,1992,27:5483-5496)用相同材料做出的实验数据较为吻合,证明了利用宏微观双范围渐进展开方法分析包含各向异性损伤情况碳纤维增强复合材料力学性质的有效性。
基金the National Natural Science Foundation of China (No. 50439010)
文摘Steel wire wound reinforced flexible pipe in this study mainly consists of multiple anisotropic steel wire wound reinforcement layers and multiple isotropic rubber layers.Based on 3D anisotropic elastic theory,the analytic solutions of stresses and elastic deformations of steel wire wound reinforced rubber flexible pipe under internal pressure are presented.As the adjacent reinforcement layers with wound angle have different radii,the single reinforcement layer shows the effect of tensile-shear coupling.Moreover,the static loading test results of steel wire wound reinforced rubber flexible pipe under internal pressure are basically coincided with the calculated values by present method.
基金Project supported by the National Natural Science Foundation of China(Nos.51320105013 and 51178413)the National High-Tech R&D Program(863)of China(No.2012AA050903)
