Three-dimensional shakedown analysis of fiber-reinforced metal matrix composite (FRMMC) layered plasma-facing component for high heat flux loading

Copper alloys have been considered as a structural material for the heat sink substrate of a plasma-facing component (PFC) due to their excellent thermal conductivity. However, insufficient high temperature strength and large thermal expansion set the limitations to structural applications. Fiber-reinforced metal matrix composites (FRMMCs) can be a candidate for a structural material for the future PFCs due to the excellent high temperature strength. Since the FRMMCs of the PFCs are exposed to thermal and mechanical loads, the resulting stress fields in mesoscopic level are highly heterogeneous and often exceed the yield limit of the matrix. The shakedown limit was investigated as the safety criterion of the FRMMCs considering the fusion-relevant thermomechanical loads. In this work, the shakedown theorems were formulated with FEM and the large-scale nonlinear optimization program. The shakedown formulation was extended to three-dimensional models. The shakedown limits were determined for SiC fiber and Cu alloy FRMMC composite system. The stress and temperature loading paths of FRMMC components were determined in the fusion-relevant loading. The thermomechanical loading paths were compared with the shakedown limits. The results showed that the loading paths in the high heat flux (HHF) operation condition were partly covered by the area of shakedown limits. It was interpreted that the FRMMC layers may undergo low cycle fatigue.