Elastic-Plastic Stress Behaviour of FGM Cylinders under Thermal and Rotational Loads: Role of Material Gradation, Temperature and Rotational Speed in Plastic Zone Propagation

The primary objective of this study is to analyze the impacts of thermal loading, material composition, radius ratios, and rotational speeds on the initiation and progression of plastic zones in functionally graded cylinders. To achieve this, the problem approached under plane strain conditions, employing Tresca’s yield criterion alongside its associated flow rule to determine the onset of yielding. Two plastic regimes dependent on stress variations with temperature incorporated into the analysis. A power-law distribution applied to model the radial variations in Young’s modulus, yield stress, thermal conductivity, thermal expansion coefficient, and material density. The governing equations solved analytically across three deformation zones: elastic, elastic-plastic, and fully plastic. The resulting formulations predict the conditions for yielding initiation, considering rotational speed, temperature, material properties, and radius ratio. Numerical simulations, conducted using MATLAB, validate the analytical solutions and highlight the significant influence of thermal gradients, rotational speeds, and material characteristics on yielding behaviors. The findings suggest that altering the thermal gradient, even under constant rotational speeds and material configurations; can dramatically change the location of yielding, the governing deformation regime, and the critical rotational speed necessary for plastic deformation.