Determination of forming limits of high strength sound-deadening laminated sheet

Abstract

High strength sound-deadening laminated sheet consists of high strength steel sheets and a viscoelastic polymeric adhesive with high vibrational damping characteristics. In this study, to evaluate formability of sound-deadening laminated sheet, forming limit curves (FLC) were determined. The high strength sound-deadening laminate sheet was fabricated with dual phase (DP) 590 steel sheets as outer skins and polymeric adhesive as a core by roll bonding process. The punched dome tests (Nakajima tests) were performed with varying specimen width. On the specimen prior to deformation, a stochastic pattern was applied to the surface using a white and black spray. Until the fracture occurs, the strain distribution was measured in the stereo image using digital image correlation (DIC) system. FLC of the laminated was successfully determined by capturing limit strains near fracture as well as calculating them according to the ISO standards. FLC of the laminated sheet is slightly higher than that of DP590 sheet but is not significantly different.