Analysis of Thermal Stresses in a Ceramic-to-Metal Cylindrical Joint With a Homogeneous Elastic Medium

It is well known that large thermal stresses arise in a ceramic-to-metal joint because of thermal expansion mismatch. Therefore, to avoid fracture of a joint, it has been recommended a joint in which thermal expansion coefficient of a ceramic member is smaller than that of a metal member. The joint is called a “compressive” joint, because it was believed that only compressive stresses occur in the ceramic member. Since ceramic is about ten times as strong in compression as in tension, this joint is considered stronger than a tensile joint. A finite element calculation (FEC), however, has shown that a large tensile stress is generated even in ceramic part of a compressive joint. The aim of this study is to clarify stress distribution in a compressive joint by solving analytically the stress equation of the joint. For convenience, we deal with a special joint in which the elastic constants of the ceramic member are assumed to be the same as those of the metal member. The result of the analysis gives the same stress distribution obtained by FEC, and its value of the tensile stress agrees fairly well with that of FEC.