Numerical simulation for the multi-point stretch forming process of sheet metal

Flexibility in metal forming

An application of the Kriging method in global sensitivity analysis with parameter uncertainty

Multi-point forming (MPF) is a new flexible technique for manufacturing three-dimensional sheet metal parts. In this procedure, a pair of opposed matrices of punch elements substitute for the conventional fixed shape die sets, and the sheet metal can be formed rapidly between the matrices. Extensive numerical simulations of the processes for forming spherical and saddle-shaped parts were carried out by dynamic explicit finite element analysis. The contacting process between sheet metal and punch elements in MPF was investigated, and the variations of forming force with respect to the tool travel were analyzed. The wrinkling processes were simulated, and the MPF limit curves without wrinkles for spherical and saddle-shaped parts were obtained. Dimple is a particular defect in MPF, through the comparison of the thickness strains calculated by solid FE and shell FE, the finite elements appropriate for the numerical analysis of dimpling were detected, and the limit forming force without dimples was determined. Springback processes of MPF were simulated based on explicit-implicit algorithm. The springbacks and their distributions under different conditions were investigated.

Numerical investigation of multi-point forming process for sheet metal: wrinkling, dimpling and springback.

Forming Limit Stress Diagram Prediction of Aluminum Alloy 5052 Based on GTN Model Parameters Determined by In Situ Tensile Test

Three-dimensional sheet metal continuous forming process based on flexible roll bending: Principle and experiments

Multi-point stretch forming (MPSF) technology is a flexible forming method, and it eliminates the need to the traditional fixed shaped-stretching die and, therefore, is a suitable method for forming small batch quantities of aircraft outer skin parts. Multi-point stretch die (MPSD) is composed of a punch element matrix, the size of punch elements and the radius of the hemispherical end of elements are the two important geometrical parameters of MPSD and they are major factors to influence the shape accuracy of MPSF parts. The smaller size of punch elements makes the punch element number of MPSD larger in the same area. MPSDs with different element numbers and different hemispherical end radii are used for stretch spherical and toroidal saddle-shaped parts. The dimples and the shape error of MPSF parts were analyzed, and the results show the influences of punch element number and element hemispherical end radius on forming results. MPSF tests show that the forming effect of MPSF is excellent.

Zhong-Yi Cai

Papers

Numerical simulation for the multi-point stretch forming process of sheet metal

Three-dimensional sheet metal continuous forming process based on flexible roll bending: Principle and experiments

Numerical investigation of the influence of punch element in multi-point stretch forming process

Study on the continuous roll forming process of swept surface sheet metal part

Finite element simulation of multi-point sheet forming process based on implicit scheme