Effect of the volume of a functionally graded material layer on frictionally excited thermoelastic instability

A finite element model is used to identify the effect of the volume of a functionally graded material (FGM) on thermoelastic instability (TEI). An optimal FGM volume that exhibits the highest critical speed was found to exist. Beyond the optimal FGM volume, the critical speed is much lower than that of a homogeneous steel layer. For all FGM volumes, the performance against TEI is dominant for the same nonhomogeneous parameter, which determines the compositional shape of the material property grading in the FGM. In addition, the thermal conductivity of the frictional material and the modulus of elasticity of the FGM were found to have the most significant impact on an increase in the critical speed.