多场载荷下考虑小尺度效应的非均质晶体内孔洞收缩特性

发布时间：2018-02-11 10:12

本文关键词： 小尺度效应非均质材料多场载荷孔洞愈合热动力学势　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：非均质材料以其独特的材料性质随位置变化的分布特性,在各种极端环境及多场载荷作用的工程结构中得到广泛应用。本文以非局部弹性理论为基础,研究力、热、电、磁多场载荷下考虑小尺度效应的非均质材料内部的微观损伤愈合规律。在建立材料性质沿径向指数分布的非均质体内孔洞动态收缩的力学模型后,利用非局部弹性理论得到非均质体内孔洞边缘扩散层中的应变能,并结合晶格扩散和化学位梯度变化规律求出非均质晶体内孔洞收缩速率和自愈时间的解析表达式。结果表明小尺度效应可以通过增加晶体内孔洞的收缩速率和减小内孔洞愈合到稳定的尺寸来有效的促进非均质晶体内孔洞自愈;当材料特性沿径向的分布指数为1时将获得最佳的内孔洞收缩结果;适当改变环境温度变化和施加特定的电、磁场也能促进内孔洞自愈收缩;非均质压电体周围的外加电势会对其内孔洞的收缩速率起到较大的影响。
[Abstract]:Non-homogeneous materials are widely used in engineering structures with various extreme environments and multi-field loads due to their unique distribution characteristics of material properties varying with location. This paper studies force, heat and electricity on the basis of non-local elastic theory. The microcosmic damage healing law of heterogeneous materials with small scale effect under multi-field magnetic loading. The dynamic shrinkage model of the pores in heterogeneous materials with radial exponential distribution of material properties is established. Using the nonlocal elastic theory, the strain energy in the diffusion layer at the edge of the hole in the heterogeneous body is obtained. The analytical expressions of shrinkage rate and self-healing time of pores in heterogeneous crystals are obtained by combining the law of lattice diffusion and chemical potential gradient. The results show that the small-scale effect can be achieved by increasing the shrinkage rate and decreasing the shrinkage rate of the pores in the crystals. The small inner cavity heals to a stable size to effectively promote the self-healing of the inner hole in the heterogeneous crystal; When the distribution index of material characteristics along the radial direction is 1:00, the optimum shrinkage of the inner cavity will be obtained, and the magnetic field can also promote the self-healing shrinkage of the inner hole by changing the ambient temperature and applying specific electricity. The external potential around the heterogeneous piezoelectric body will have a great effect on the shrinkage rate of the inner hole.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB303

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