Surface Effects on Thermal Stresses Around the Nanohole in Thermoelectric Material
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摘要: 基于完整Gurtin-Murdoch(G-M)低阶表面能模型,进一步探讨了纳米尺度下表面效应的影响. 建立了合理考虑构型变化的应力边界条件,实现了研究尺度从宏观到微观的转变. 利用复变函数理论和保角映射技术,构建了用于纳米尺度下的热-电-力理论框架模型,得到了热电基体中纳米孔周围热场、温度场以及应力场的半解析解. 数值结果表明,相对于完整G-M模型,简化G-M模型(忽略孔洞构型变化的影响)往往会高估表面效应和远场热电载荷对热应力分布的影响. 此外,表面效应的存在将在一定程度上缓解纳米孔周围的热应力集中.
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关键词:
- 热电材料 /
- 完整Gurtin-Murdoch模型 /
- 表面效应 /
- 复变函数理论 /
- 纳米孔
Abstract: Based on the complete Gurtin-Murdoch (G-M) low-order surface energy model, the surface effects at nanoscale were further explored. The transition from macroscale to microscale was achieved through construction of reasonable stress boundary conditions in view of the change of hole geometry configuration. With the series expansion techniques and complex variable methods, the semi-analytic solutions for the electric field, the temperature field, and the full stress field in the vicinity of the nanohole within the thermoelectric matrix were derived eventually with a built thermal-electrical-force theoretical framework model at nanoscale. Numerical results show that, compared with the complete G-M model, the simplified G-M model (neglecting the effects of nanohole geometry changes) would overestimate the surface effects and far-field thermoelectric loading effects on the thermal stress distributions. In addition, the surface effects can relieve the thermal stress concentration around the nanohole to some extent. -
表 1 Bi2Te3和PbTe的材料性能
Table 1. Properties of the Bi2Te3 material and the PbTe material
δ/(S/m) E/GPa ε/(V/K) κ/(W/(m·K)) λ/K-1 ν Bi2Te3 1.1×105 47 2×10-4 1.6 2.7×10-5 0.4 PbTe 1×104 58 3×10-4 1.5 2×10-5 0.29 表 2 不同表面弹性与表面张力共同作用下的环向应力值(单位:MPa)
Table 2. Hoop stresses under the combined actions of different surface elasticities and surface tensions (unit: MPa)
surface elasticity γ/(N/m) δtt/MPa τs=0.2 N/m τs=0.6 N/m τs=1.0 N/m 0 138.587 0 136.587 0 134.587 0 0.2 138.573 3 136.573 3 134.573 4 0.6 138.545 8 136.546 0 134.546 1 1.0 138.518 3 136.518 6 134.518 9 -
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