功能梯度压电材料壳体热残余应力

功能梯度压电材料结构成型冷却后会出现热残余现象,影响结构强度.借鉴复合材料层合结构的研究方法,将功能梯度压电材料球壳和圆柱壳沿厚度分为若干层,各层视为均匀材料,根据层间连续条件导出递推关系,得到显式的力—电—热多场耦合热残余解.统一了多层功能梯度压电材料壳体和连续功能梯度压电材料壳体热残余解.对于前者,其解为精确解；对于后者,其解为渐近解,随层数增加而收敛于精确解.其解也适用于功能梯度压电材料涂层.该方法对材料性能的变化方式(函数)没有要求,适应性强.并讨论影响热残余应力和界面强度的因素,球壳因双曲率的影响,热残余应力显著大于柱壳.

THERMAL RESIDUAL STRESSES OF FUNCTIONALLY GRADED PIEZOELECTRIC SHELLS

Thermal residual phenomenon occurs in functionally graded(FG) piezoelectric structures when workpieces are cooling and affects their strength.A FG piezoelectric hollow sphere or circular cylinder was divided to a number of layers through its thickness like a composite laminate,each layer with constant material properties.According to the interfacial continuity conditions,a recursive relation was built and the explicit thermal residual solutions with piezothermoelastic coupling were deduced.The solutions were suitable for both multi-layered and continuous FG piezoelectric shells.The solutions are exact for multi-layered FG piezoelectric shells,and approximate for continuous FG piezoelectric shells and converge to the exact solutions when the number of layers increases.The solutions also hold for FG piezoelectric coatings on a substrate.This method is independent of the distribution functions of material properties through thickness and shows its adaptability.The factors to affect thermal residual stresses and interfacial strength were discussed.The thermal residual stresses of a sphere with double curvatures are much bigger than those of a cylinder.