爆炸冲击载荷下航空铝合金平板动态响应数值分析方法

为得到适用于爆炸冲击载荷下航空铝合金平板动态响应的数值分析方法,采用LS-DYNA显式动力学分析软件对爆炸冲击载荷下的铝合金平板进行数值仿真计算.主要研究了不同的任意Lagrange-Euler(拉格朗日-欧拉)网格（ALE）输运步算法、流固耦合方式、流固耦合点数量、网格尺寸、有限元单元类型对计算结果的影响.通过计算结果与实验结果的分析对比,表明采用van Leer+HIS输运步算法、罚函数耦合方式、在流体网格与结构网格之间采用3个耦合点、结构网格尺寸与空气域网格尺寸比例设为2∶1、结构单元采用163号壳单元时可以较为准确地计算航空铝合金平板在爆炸冲击载荷下的动态响应,并且能提高计算效率,节约计算时间.     

三参量固体模型粘弹性输流管道的动力特性分析

推导了三参量固体模型粘弹性输流管道的振动微分方程 ,计算了在不同无量纲松弛系数和弹性常数比下管道的无量纲临界流速和无量纲自振复频率 ,并给出了前三阶复频率与流速的关系 .计算结果表明 ,质量比、无量纲松弛系数及无量纲弹性常数比对输流管道的动力特性均有影响 .     

三参量固体模型粘弹性输液管道的动力特性分析

推导了三参量固体模型粘弹性输流管道的振动微分方程，计算了在不同无量纲松弛系数和弹性常数比下管道的无量纲临界流速和无量纲自振复频率，并给出了前三阶复频率与流速的关系。计算结果表明，质量比，无量纲松弛系数及无量纲弹性常数比对输流管道的动力特性均有影响。     

对平面运动刚体加速度瞬心问题的进一步讨论

讨论了与加速度瞬心相关的几个问题,进一步深化了对加速度瞬心概念的理解．     

Binding energies of impurity states in strained wurtzite GaN/Al_xGa_(1-x)N heterojunctions with finitely thick potential barriers

Ground state binding energies of donor impurities in a strained wurtzite GaN/AlxGal_xN heterojunction with a po- tential barrier of finite thickness are investigated using a variational approach combined with a numerical computation. The built-in electric field due to the spontaneous and piezoelectric polarization, the strain modification due to the lattice mismatch near the interfaces, and the effects of ternary mixed crystals are all taken into account. It is found that the binding energies by using numerical wave functions are obviously greater than those by using variational wave functions when impurities are located in the channel near the interface of a heterojunction. Nevertheless, the binding energies using the former functions are obviously less than using the later functions when impurities are located in the channel far from an interface. The difference between our numerical method and the previous variational method is huge, showing that the former should be adopted in further work for the relevant problems. The binding energies each as a function of hydrostatic pressure are also calculated. But the change is unobvious in comparison with that obtained by the variational method.     

Analysis of coupled-mode flutter of pipes conveying fluid on the elastic foundation

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