热电材料热冲击阻力性能的研究
发布时间：2018-11-17 14:21
【摘要】：随着人类科学技术的不断发展与进步,人类对清洁能源的需求量也越来越大。热电材料作为一种新型功能材料,能够在电能和热能之间实现能量相互转化。但是热电材料在服役期间常因热冲击而产生机械失效甚至断裂,因此对热电材料的热冲击应力及断裂分析是非常必要的。本论文通过解析法对热电材料内部的应力场及断裂特性进行了理论分析,完成了对单层和层合热电材料板的热冲击应力和断裂力学分析。首先通过热电材料的物理本构方程获得温度场,再根据热弹性力学的相关理论求得应力场,最后以Be2Te3基热电材料为例进行分析。发现在热冲击初始阶段热应力比较大,然后热应力随着时间的增加而逐渐减小。在瞬态过程中单层热电材料板的最大热应力发生在冷端面,而层合热电材料板的最大热应力发生在热端面。另外对含有边缘裂纹单层热电材料板完成了断裂力学分析,通过权函数法求得应力强度因子,发现板的厚度越大,相应的应力强度因子也就越大。然后通过数值法对含有边缘裂纹单层热电材料板所能承受的热冲击阻力进行了研究,发现板的厚度越大,其所能承受的热冲击阻力就越小。因此从断裂力学的角度来看,同样条件下薄板更具有良好的断裂力学性能。最后,通过数值拟合得到了计算热电材料所能承受的热冲击阻力的经验公式,此公式可以用于指导热电器件的断裂力学可靠性设计。同时,本研究对热电器件工作期间发生的机械失效也产生更加深入的理解。
[Abstract]:With the development and progress of science and technology, the demand for clean energy is increasing. As a new functional material, thermoelectric material can transform energy between electric energy and heat energy. However, mechanical failure and even fracture of thermoelectric materials are often caused by thermal shock during service, so it is necessary to analyze thermal shock stress and fracture of thermoelectric materials. In this paper, the stress field and fracture characteristics of thermoelectric materials are analyzed by analytical method, and the thermal shock stress and fracture mechanics of single-layer and laminated thermoelectric plates are analyzed. First, the temperature field is obtained by the physical constitutive equation of thermoelectric material, then the stress field is obtained according to the theory of thermoelastic mechanics. Finally, the thermoelectric material based on Be2Te3 is analyzed as an example. It is found that the thermal stress is relatively large in the initial stage of thermal shock and then decreases with the increase of time. In the transient process, the maximum thermal stress of single-layer thermoelectric plate occurs on the cold end surface, while the maximum thermal stress of laminated thermoelectric plate occurs on the hot end surface. In addition, the fracture mechanics analysis of single-layer thermoelectric material with edge cracks is carried out. The stress intensity factor is obtained by the weight function method. It is found that the greater the thickness of the plate, the greater the corresponding stress intensity factor. Then the thermal shock resistance of single-layer thermoelectric plate with edge cracks is studied by numerical method. It is found that the greater the thickness of the plate, the smaller the thermal shock resistance it can withstand. Therefore, from the point of view of fracture mechanics, the thin plate has better fracture mechanical properties under the same conditions. Finally, an empirical formula for calculating the thermal shock resistance of thermoelectric materials is obtained by numerical fitting, which can be used to guide the reliability design of fracture mechanics of thermoelectric devices. At the same time, this study also produces a deeper understanding of the mechanical failure of thermoelectric devices.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34
本文编号：2338102
[Abstract]:With the development and progress of science and technology, the demand for clean energy is increasing. As a new functional material, thermoelectric material can transform energy between electric energy and heat energy. However, mechanical failure and even fracture of thermoelectric materials are often caused by thermal shock during service, so it is necessary to analyze thermal shock stress and fracture of thermoelectric materials. In this paper, the stress field and fracture characteristics of thermoelectric materials are analyzed by analytical method, and the thermal shock stress and fracture mechanics of single-layer and laminated thermoelectric plates are analyzed. First, the temperature field is obtained by the physical constitutive equation of thermoelectric material, then the stress field is obtained according to the theory of thermoelastic mechanics. Finally, the thermoelectric material based on Be2Te3 is analyzed as an example. It is found that the thermal stress is relatively large in the initial stage of thermal shock and then decreases with the increase of time. In the transient process, the maximum thermal stress of single-layer thermoelectric plate occurs on the cold end surface, while the maximum thermal stress of laminated thermoelectric plate occurs on the hot end surface. In addition, the fracture mechanics analysis of single-layer thermoelectric material with edge cracks is carried out. The stress intensity factor is obtained by the weight function method. It is found that the greater the thickness of the plate, the greater the corresponding stress intensity factor. Then the thermal shock resistance of single-layer thermoelectric plate with edge cracks is studied by numerical method. It is found that the greater the thickness of the plate, the smaller the thermal shock resistance it can withstand. Therefore, from the point of view of fracture mechanics, the thin plate has better fracture mechanical properties under the same conditions. Finally, an empirical formula for calculating the thermal shock resistance of thermoelectric materials is obtained by numerical fitting, which can be used to guide the reliability design of fracture mechanics of thermoelectric devices. At the same time, this study also produces a deeper understanding of the mechanical failure of thermoelectric devices.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34
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