【作者】 李同顺；

【导师】 宋天舒；

【作者基本信息】 哈尔滨工程大学 ， 结构工程， 2009， 硕士

【摘要】 由于压电材料本身的力电耦合特性,压电材料已被广泛应用于现代化科学技术,如声纳传感器、力电耦合执行器、压电电源补给装置及位置调节器等。这些装置均是在力电耦合场共同作用下进行工作,故材料本身的缺陷,如位错、裂纹、夹杂等对其工作特性及力电耦合特性产生很大影响。因此,研究在力电耦合场共同作用下含有缺陷的压电材料的力学性能具有重要意义。本文采用有限元法研究压电介质中近场圆形孔洞对瞬态SH波的散射和动应力集中问题。有限元法原理在数学上是将偏微分方程的初边值问题划归一组常微分方程的初值问题或一组规则代数方程。然后,采用直接积分法进行求解,得到各节点和单元的位移、应力的时程解。用有限元模拟波动问题,首先要解决人工边界的设置问题,由于要从无限域中截取有限区域来模拟无限域,所以要引入人工边界。其次是解决时空离散带来的各种不利影响,以减少误差。还要考虑荷载的施加问题以及模型大小对解题的影响问题。本文对要解决的问题建立了有限元模型,并用通用有限元分析软件ANSYS进行了计算,给出了部分节点的位移、应力时程解和孔边动应力集中系数,并对结果进行了讨论。本文的具体工作如下：研究了瞬态SH波入射到压电介质中界面附近多个圆孔引起散射时,讨论了两圆孔距离不同时对应力、位移和动应力集中系数影响；并且研究了瞬态SH波入射到双相压电介质界面上圆孔引起散射时,讨论了在上部压电介质不同时对应力、位移和动应力集中系数影响。更多还原

【Abstract】 Due to this intrinsic coupling behavior, piezoelectric materials are widely used in modern technology such as high power sonar transducers, electro-mechanical actuator, piezoelectric power supplies and micro-positioner. These devices are designed to work under combined electro-mechanical loads. The presence of various defects, such as dislocations, cracks and inclusions, can greatly influence their characteristics and coupled behavior. Therefore, it is of vital importance to study the electro-elastic fields as a result of the presence of defects.The present thesis investigates the scattering problems and the dynamic stress concentration problems of SH-wave by circular cavities in near field of piezeoelectric medium by the method of FEM. The FEM is a method of which transform the partial differential-coefficient equation’s initial and boundary value issue to ordinary differential-coefficient equation’s initial and boundary value problem or a set of regular algebra equation. Then, use the direct integral calculus method of NEWMARK to solve solution, and get each node and element’s displacement and stress solution vs. time. There are two problems in simulating SH-wave issue by finite element method. The first is establishing artificial boundary problem, because of simulating the infinite field from the finite field in which intercept from the infinite field, so we introduce artificial boundary. The second is solving all kinds of disadvantageous influence in space-time dispersing to reduce error. In additional, the problems of load’s infliction and model’s size should be considered. In this article, we found the finite element model in allusion to the problem above, solved the equation by the general finite element analysis software ANSYS, gave some node’s displacement and stress solution vs. time and the dynamic stress concentration at the edge of cavity, discussed the result. Our analytic works in concrete are mainly as follows: Scattering of transient SH-wave and dynamic stress conceatration problem are investigated by two circular cavities under interface in piezeoelectric media.The influence on stress and displacement and dynamic stress concentration of different distance of zhe two cavteties are discussed. Then,Scattering of transient SH-wave and dynamic stress conceatration problem are investigated by an interface circular cavity in two dissimilar piezeoelectric media.The influence on stress and displacement and dynamic stress concentration of different piezeoelectric media is discussed.更多还原