Unloading Behavior of Elastic-power-law Strain Hardening Materials Indented by Elastic Indenter

Abstract Both strain hardening and indenter elastic deformation usually cannot be neglected in engineering contacts. By the finite element (FE) method, this paper investigates the unloading behavior of elastic-power-law strain-hardening half-space frictionlessly indented by elastic sphere for systematic materials. The effects of strain hardening and indenter elasticity on the unloading curve, cavity profile during unloading and residual indentation are analyzed. The unloading curve is observed to follow a power-law relationship, whose exponent is sensitive to strain hardening but independent upon indenter elastic deformation. Based on the power-law relationship of the unloading curve and the expression of the residual indentation fitted from the FE data, an explicit theoretical unloading law is developed. Its suitability is validated numerically and experimentally by strain hardening materials contacted by elastic indenter or rigid flat.