Metalforming limit diagrams according to the T-criterion
(EN)
Andrianopoulos, NP
(EN)
A generalized form of the T-criterion of failure is applied in the case of metalforming processes to predict metalforming limit diagrams. According to this criterion an upper limit of permissible deformations in metalforming is set by either a critical value of the elastic strain energy density (T(V,0)) of volume changes, or a respective critical value of the strain energy density (T(D,0)) of shape changes, of the material. When T(V,0) is reached the material fails by unstable crack propagation, whilst it fails by general yielding when T(D,0) is reached. Consequently, the total failure locus consists of two curves, one of final failure by elastic fracture and another of final failure by general yielding. Experimental evidence from the existing literature shows good agreement with the present predictions.
(EN)
