Optimum material composition design for thermal stress reduction in FGM lathe bit

Nowadays, many attempts to apply the concept of functionally graded material (FGM) to major industrial parts are intensively being in progress. A FGM lathe bit is one of such applications, in which a dual-phase graded region is inserted between shank and tip in order to enforce the material composition continuity. The severe thermal stress concentration that has been occurred near the tip–shank interface in traditional lathe bits could be significantly relaxed if the material composition distribution in the graded region is appropriately tailored. This paper is concerned with the optimum design of the material composition distribution in lathe bit to minimize the thermal stress level. Illustrative numerical results as well as theoretical formulations are presented. The optimum distribution greatly reduces the global and local thermal stress levels and the optimization scheme shows the robustness and the high convergence rate.