反平面剪切动态扩展裂纹尖端的弹-粘塑性场

采用Bingham弹性-粘塑性模型对反平面剪切动态扩展裂纹尖端的应力应变场进行了渐近分析．给出了适当的位移模式、推导了渐近方程并且给出了数值解．分析和计算表明对于低粘性情况,裂纹尖端场具有对数奇异性．对于高粘性情况,裂纹尖场具有幂奇异性A·D2对于临界情况,两种奇异性可以相互转换．揭示了粘性在裂纹尖端场研究中的重要作用．     

轴向流中悬臂柔性板流固耦合动力特性研究

论文从理论分析和实验研究两方面对轴向流中悬臂柔性板流固耦合动力特性作了研究.基于板的轴向不可延伸假设,采用Hamilton变分原理,推导了轴向流中悬臂板非线性运动偏微分方程,通过面元法计算悬臂板上下面压力差.采用伽辽金法离散该非线性运动偏微分方程,通过无量纲化物理参数,研究了系统无量纲颤振临界速度,给定流速下悬臂板末端响应时程曲线及板的振动响应,并与风洞模型实验结果进行了对比.研究结果表明,系统发生Hopf分叉,流体流速大于颤振临界速度时,悬臂板发生稳定的极限环颤振,悬臂板振幅、频率随流速的增加而增大.     

Elastic-viscoplastic fields near the tip of a propagating crack under anti-plane shear

The elastic-viscoplastic model proposed by Bingham was used to analyse the stress and strain surrounding the tip of a propagating crack under antiplane shear. The proper displacement pattern was given ; the asymptotic equations were derived and solved numerically. The analysis and calculation show that for smaller viscosity the crack-tip possesses logarthmic singularity, and for larger viscosity it possesses power-law singularity.In critical case, the two kinds of singularity are consistent with each other. The result revealed the important role of viscosity for crack-tip field.