Effects of Peening Conditions and Plate Size on Forming Shape in Peen Forming

The effects of shot velocity, shot diameter, and square plate size (width and thickness) on the shape of aluminum alloy A5052-H34 plates after peen forming were investigated by numerical simulation. Numerical simulation was conducted in three steps: in Step 1, shot impact was calculated for a small area using the dynamic explicit finite element method (FEM); in Step 2, the nodal coordinates, stress, and strain distributions calculated in Step 1 were used to calculate the plastic strain distribution in free deformation using static implicit FEM; and in Step 3, the plastic strain distribution obtained in Step 2 was used to calculate plate deformation using the static implicit FEM. The FEM results of the peenformed shapes agreed well with the experimental results, confirming the validity of the numerical simulation method. As shot velocity was increased, the plate shape shifted from a spherical to a cylindrical surface. When the plate width (=length) was large or the thickness was small, the shifting shot velocity decreased side. The strain in the center of the thickness at the plate edge had a limit for each plate size, because peen forming cannot apply compressive strain to the plate. Above the limited compressive strain, a shift from a spherical to a cylindrical surface occurred.