Radial Basis Functional Model of Multi-Point Dieless Forming Process for Springback Reduction and Compensation

Misganaw Abebe,Jun-Seok Yoon,Beom-Soo Kang

doi:10.3390/met7120528

Abstract

Springback in multi-point dieless forming (MDF) is a common problem because of the small deformation and blank holder free boundary condition. Numerical simulations are widely used in sheet metal forming to predict the springback. However, the computational time in using the numerical tools is time costly to find the optimal process parameters value. This study proposes radial basis function (RBF) to replace the numerical simulation model by using statistical analyses that are based on a design of experiment (DOE). Punch holding time, blank thickness, and curvature radius are chosen as effective process parameters for determining the springback. The Latin hypercube DOE method facilitates statistical analyses and the extraction of a prediction model in the experimental process parameter domain. Finite element (FE) simulation model is conducted in the ABAQUS commercial software to generate the springback responses of the training and testing samples. The genetic algorithm is applied to find the optimal value for reducing and compensating the induced springback for the different blank thicknesses using the developed RBF prediction model. Finally, the RBF numerical result is verified by comparing with the FE simulation result of the optimal process parameters and both results show that the springback is almost negligible from the target shape.

Highlights

Springback is a common and critical existence in sheet metal forming processes, which is caused by the elastic redistribution of the internal stresses after unloading of the external forces
The radial basis function (RBF) numerical result is verified by comparing with the finite element (FE) simulation result of the optimal process parameters and both results show that the springback is almost negligible from the target shape
This study proposed surrogate modeling to replace the computational expensive FE simulation as a function of target curvature radius, blank thickness, and punch holding time after the final displacement of the punch

Summary

Introduction

Springback is a common and critical existence in sheet metal forming processes, which is caused by the elastic redistribution of the internal stresses after unloading of the external forces. Proposed the multi-step forming to reduce the unloading springback on multi-point forming using numerical simulation. Shim et al [3] investigates the tension force on MDF stretch forming process of aluminum alloy sheet to reduce the induced springback using FE simulation. Using only FE simulation to compensate the machine tool geometry or any design or process parameters is computationally expensive. To overcome this problem, this study proposed surrogate modeling to replace the computational expensive FE simulation as a function of target curvature radius, blank thickness, and punch holding time (stress relief period) after the final displacement of the punch

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Conclusion