Nonintrusive strain measurement systems

Measurement of deformation along the surface of sheet metal during the forming process helps in determining the surface profile, thickness profile, and the state of the stress. Knowledge of these process parameters during the forming process helps in controlling the forming process and the quality of the finished products. The authors describe a nonintrusive strain evaluation technique by which in-plane and out-of-plane coordinates are independently measured and correlated to give an overall strain profile. The principles of the technique and some preliminary results are presented