Theoretical and experimental analysis of sheet metal formability limits

The formability of sheet metals can be assessed by the forming limit diagra m (FLD), In this study, a theoretical model is introduced for calculating t he FLD, A << many slice >> approach is used to simulate neck growth. The ef fect of strain-hardening exponent (n), strain rate sensitivity (m), anisotr opy parameter (r) and grain size (d) have been investigated. Also, the FLDs of ST12 steel sheet with different grain sizes have been experimentally de termined. It is shown that the FLD is quite sensitive on n, m, r and d, The model prediction is compared with the experimental results.