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Nonlinear progressive damage model for composite laminates used for low-velocity impact 总被引:1,自引:0,他引:1
In order to effectively describe the progressively intralaminar and interlam- inar damage for composite laminates, a three dimensional progressive damage model for composite laminates to be used for low-velocity impact is presented. Being applied to three-dimensional (3D) solid elements and cohesive elements, the nonlinear damage model can be used to analyze the dynamic performance of composite structure and its failure be- havior. For the intralaminar damage, as a function of the energy release rate, the damage model in an exponential function can describe progressive development of the damage. For the interlaminar damage, the damage evolution is described by the framework of the continuum mechanics through cohesive elements. Coding the user subroutine VUMAT of the finite element software ABAQUS/Explicit, the model is applied to an example, i.e., carbon fiber reinforced epoxy composite laminates under low-velocity impact. It is shown that the prediction of damage and deformation agrees well with the experimental results. 相似文献
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高温超导体中电子的自旋和电荷一样重要。文章对高温超导体的电子结构、磁性相互作用和关于单胞层La1.85Sr0.15CuO4存在超导态的最新实验结果作了扼要的介绍,并指出,电子的有效自旋耦合应当是产生高温超导电性的原因。 相似文献
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Effective spin coupling between conduction electrons mediated by local Cu moments in the doped CuO2 plane may induce the instability of the normal states of conduction electrons and pairing at Cu stes,where the superexchange interaction between local moments influenced by hole doping has been found to be Ising-like in recent experiments.By a mean field approach,we show that spin pairing and strong pair-pair interaction in the doped antiferromagnetic ordered Ising-like CuO2 plane gives rise to high-temperature superfluid condensation and the exceptional features of quasi-particle excitation in cuprates such as spin gap,pseudogap,and the linear temperature dependence of resistivity ρab in the normal states. 相似文献
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