Experimental and simulation study on evolution of stress and strain during the hole expansion

The hole expansion experiments were performed on LY12CZ aluminum alloy plate using a mandrel. The extrusion force and strain around the hole were measured under various interference values and friction coefficients. A 3D finite element model was built and the expansion process was simulated according to the experimental conditions. The results of experiments and simulations reveal the following regularities: 1) the evolution and distribution of stress and strain near the expanded hole; 2) the variation of the extrusion force under different interference values and friction coefficients; 3) the distribution of the tangential stress along the depth of the hole; 4) the origination and evolution of residual compressive stress around the hole. The simulation results are in good agreement with the experiments, which validate the reliability of the simulations.