Unloading analysis of elastically and plastically graded hemispherical contact with rigid flat

Abstract

Abstract The present work puts forward a finite element based loading and unloading analysis of radially functionally graded flattening hemispherical contact. Two types of gradations are used viz. elastic gradation, where modulus of elasticity and tangent modulus (for bilinear isotropic hardening) is varied keeping the yield strength fixed and plastic gradation, where yield strength is varied keeping the modulus of elasticity and tangent modulus fixed. Loading and unloading analysis is performed for different values of elastic and plastic inhomogeneity parameters and their effects on different contact parameters are analyzed. Effect of gradation on deformation behavior and stress distribution while loading and unloading of elastically and plastically graded hemisphere are discussed. During the unloading process, secondary plastic flow was also observed and discussed for different gradation parameters. Loss of energy of the material during loading-unloading due to plasticity is also analyzed in connection with gradation parameters.