|About this Abstract
||NUMISHEET 2021: The 12th International Conference on Numerical Simulation of 3D Sheet Metal Forming Processes
||An Experimental Methodology to Measure the Through-thickness Strain Gradients in the VDA 238-100 Tight Radius Bend Test
||Jacqueline Noder, Clifford Butcher
|On-Site Speaker (Planned)
The VDA 238-100 tight radius bend test has received considerable interest in recent years due to its ability to produce a proportional stress state of plane strain until fracture. Fracture initiates on the convex surface where the strain can be measured using digital image correlation (DIC). However, the material layers below the surface are exposed to a severe strain gradient from plane strain tension to plane strain compression. Shifting of the neutral axis serves to unload layers in compression and re-load them in tension which activates Bauschinger effects. The present study proposes a novel analytical technique to use the DIC measurements of the surface strain, radius of curvature, thinning of the cross-section, and punch force to determine the stress and strain state at each material layer. The proposed methodology was evaluated using FEA and can be used to calibrate anisotropic yield functions and kinematic hardening models in plane strain bending.
||Definite: At-meeting proceedings