Method of Curing Deformation Prediction and Surface Reconstruction Compensation for Roller-Hemming Structures with Dissimilar Materials

Abstract

Dissimilar material structure has the advantages of both cost and performance, and has become an important means of lightweight for the new generation of autobody closure panels. However, the difference between physical properties of sheets and the complex change of adhesive material properties are easy to lead to structural curing mismatch deformation. In order to eliminate the structure deformation, a method for deformation prediction and surface reconstruction pre-compensation was proposed. Then, considering the material property transformation effect of curing degree, chemical shrinkage, and stress relaxation, a thermal-chemical-structural field coupled model for high temperature curing of hemming adhesive was established. Taking the typical aluminum/steel sheet curved-edge hemming structure as the research object, the multi-physics field curing process was simulated and analyzed, and the deformation of aluminum alloy outer panel was predicted, which was verified by non-contact measurement experiment using digital image correlation (DIC) method. Finally, the geometric compensation of curing deformation was conducted, the compensation efficiency of constraint direction, connection direction, and normal direction was compared and analyzed, and the reliability of the method was verified by experiment. The results show that compared with the traditional viscoelastic model, the multi-physics field coupling model can more accurately reflect the high temperature curing deformation of hemming structures with dissimilar materials. The geometric compensation method based on non-uniform rational B-splines (NURBS) surface reconstruction can effectively reduce the curing deformation of structures, and the normal direction compensation method is more efficient. This paper provides an important reference for the improvement of manufacturing accuracy and process optimization of the new generation of autobody closure panels with dissimilar materials.

Keywords

• dissimilar material hemming-structure
• curing deformation
• multi-physics fields
• geometric compensation
• surface reconstruction