研究了HTPB/IPDI弹性体材料单轴等速拉伸及拉伸松弛的力学特性,材料的应变率相关性及松弛特性明显,表现出了较为显著的粘弹性特征;材料在拉伸载荷下有较大的变形量。因此,将Yang L M等提出的适用于橡胶动态特性的粘-超弹本构模型改进应...研究了HTPB/IPDI弹性体材料单轴等速拉伸及拉伸松弛的力学特性,材料的应变率相关性及松弛特性明显,表现出了较为显著的粘弹性特征;材料在拉伸载荷下有较大的变形量。因此,将Yang L M等提出的适用于橡胶动态特性的粘-超弹本构模型改进应用于HTPB/IPDI弹性体的静态及准静态力学中。模型由超弹模型及粘弹模型并联组成。用实验结果对模型中的参数进行拟合,并用拟合结果预测其他应变率下的实验结果,拟合及预测结果与实验吻合较好。展开更多
The influences of time on clays are discussed first,and the concept of the instant normal compression line is proposed by analyzing the existing theories and experimental results.Based on the creep law,the relationshi...The influences of time on clays are discussed first,and the concept of the instant normal compression line is proposed by analyzing the existing theories and experimental results.Based on the creep law,the relationship between the aging time and the overconsolidation parameter is built.With the reloading equation of the UH model(unified hardening model for overconsolidated clays) used to calculate the instant compression deformation,a one-dimensional stress-strain-time relationship is proposed.Furthermore,the evolution of this relationship is analyzed,and the characteristic rate that is a function of the overconsolidation parameter is defined.Then a three-dimensional elastic-viscous-plastic constitutive model is suggested by incorporating equivalent time into the current yield function of the UH model.The new model can describe not only creep,rate effect and other viscous phenomena,but also shear dilatancy,strain softening and other behaviors of overconsolidated clays.Besides,compared with the modified Cam-clay model it requires only one additional parameter(the coefficient of secondary compression) to consider the creep law.Finally,because the proposed model can be changed into the UH model under instantaneous loading,the elastic-plastic and elastic-viscous-plastic frameworks are unified.展开更多
In this paper the Wilson nonconforming finite element is employed to solve Sobolev and viscoelasticity type equations. By means of post-processing technique, global superconvergence estimates are obtained for quasi-un...In this paper the Wilson nonconforming finite element is employed to solve Sobolev and viscoelasticity type equations. By means of post-processing technique, global superconvergence estimates are obtained for quasi-uniform rectangular meshes. Finally, an error correction scheme is presented.展开更多
文摘研究了HTPB/IPDI弹性体材料单轴等速拉伸及拉伸松弛的力学特性,材料的应变率相关性及松弛特性明显,表现出了较为显著的粘弹性特征;材料在拉伸载荷下有较大的变形量。因此,将Yang L M等提出的适用于橡胶动态特性的粘-超弹本构模型改进应用于HTPB/IPDI弹性体的静态及准静态力学中。模型由超弹模型及粘弹模型并联组成。用实验结果对模型中的参数进行拟合,并用拟合结果预测其他应变率下的实验结果,拟合及预测结果与实验吻合较好。
基金supported by the National Natural Science Foundation of China (Grant Nos. 51179003,11072016,11272031)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No.20091102110030)
文摘The influences of time on clays are discussed first,and the concept of the instant normal compression line is proposed by analyzing the existing theories and experimental results.Based on the creep law,the relationship between the aging time and the overconsolidation parameter is built.With the reloading equation of the UH model(unified hardening model for overconsolidated clays) used to calculate the instant compression deformation,a one-dimensional stress-strain-time relationship is proposed.Furthermore,the evolution of this relationship is analyzed,and the characteristic rate that is a function of the overconsolidation parameter is defined.Then a three-dimensional elastic-viscous-plastic constitutive model is suggested by incorporating equivalent time into the current yield function of the UH model.The new model can describe not only creep,rate effect and other viscous phenomena,but also shear dilatancy,strain softening and other behaviors of overconsolidated clays.Besides,compared with the modified Cam-clay model it requires only one additional parameter(the coefficient of secondary compression) to consider the creep law.Finally,because the proposed model can be changed into the UH model under instantaneous loading,the elastic-plastic and elastic-viscous-plastic frameworks are unified.
文摘In this paper the Wilson nonconforming finite element is employed to solve Sobolev and viscoelasticity type equations. By means of post-processing technique, global superconvergence estimates are obtained for quasi-uniform rectangular meshes. Finally, an error correction scheme is presented.
