Bendability Study of 7xxx Aluminum Sheets based on the DIC Technique 2019-01-1265
Bendability is a critical characteristics of sheet metal during the stamping process in automobile industry. Bending operation plays an important role in the panels forming of vehicles. In this study, the recently developed “incremental bending” method was utilized to evaluate the ambient bendability of 7xxx series avoiding bending crack. A 3D digital image correlation (DIC) measurement system is improved to capture the displacement and strain information on the stretched side of the sheet samples. The background, experimental method and data post-procedure are introduced in detail. After several sequential images acquisition and data processing, the major strain histories on the stretch zone of the samples are measured. With different bending process and parameters, the location of peak strain and the surface major strain distribution were evaluated as a function of R/T ratio (the inner radius over sheet thickness). The experimental results showed the difference bendability of 5xxx and 7xxx AA sheet. The potential applications of the relationship between the peak strain and R/T ratio are proposed.