FEM analysis of asymmetrical bending test for smart materials joints

摘要

SiC/SiC composites with a thermal coating have been developed as Smart composites for high temperature applications, where the joint techniques are indispensable for constructing large scale structures due to the fabrication and economical reasons. Since one of the important issues is the establishment of a design database for the joint strength, the testing method has to be carefully selected based on the theoretical background. In this study, the stress distribution of a SiC/SiC Composite specimen containing a butt joint Consisting of reaction-formed silicon carbide tested by the asymmetrical four-point bending test was precisely analyzed by the finite element method as a means to evaluate the applicability of analytical results. In the case without the effect of the thermal residual stresses, the shear stress distribution at the interface between the base and the joint almost agreed with the analytical theory. For the case with the residual stress, however, the shear stress near the surface was very large and the possibility of an initial crack induced by the residual stress was considered. Moreover, it was found that the residual shear stress distribution near the surface was significantly affected by the joint thickness.