功能梯度涂层壳体热残余应力分析

Thermal Residual Stresses of Shells with Functionally Graded Coatings

统一了多层功能梯度涂层和连续功能梯度涂层热残余应力分析方法,对于多层功能梯度涂层壳体,其解为精确解;对于连续功能梯度涂层壳体,采用分层近似,其解为近似解,当所取层数足够多时,近似解收敛于精确解。采用递推方法,得到了热残余变形和应力的显式解,便于涂层的优化设计。对于薄涂层,柱壳涂层的热残余应力与梁的涂层的热残余应力很接近,可以用计算梁的热残余应力的公式来计算,后者简单得多。球壳涂层因双曲率的影响,热残余应力显著大于柱壳。算例中探讨了影响涂层热残余应力及界面强度的因素。

A common solution for thermal residual stresses of multi-layered functionally graded coatings and continuous functionally graded coatings on shells is deduced.For multi-layered functionally graded coatings the solution is exact;for continuous functionally graded coatings the solution is approximate.Continuous functionally graded coatings are divided in to many layers through thickness like a composite laminate,each layer with constant material properties.The solution will converge to the exact solution when the number of layers increases.Using a recursive method,the explicit solutions of thermal residual deformation and stresses are obtained for optimization design of coatings.For thin coatings the solutions of thermal residual stresses of coatings on cylinders are very close to those of coatings on beams.The thermal residual stresses of coatings on a sphere with double curvatures are much bigger than those of coatings on a cylinder.The factors which affect thermal residual stresses and interfacial strength are discussed in the numerical examples.