Numerical investigation of the combined effects of curvature and normal stress on sheet metal formability
- 138 Downloads
A number of parts and components involved in the automotive industry are made of thin bent sheets, which are subjected to out-of-plane compressive stresses in addition to traditional in-plane stresses. Unfortunately, the classical predictions based on the conventional concept of Forming Limit Diagram (FLD) are no longer relevant when the strain distribution is heterogonous over the sheet thickness. Therefore, this conventional FLD concept is not capable of accounting for the effect of out-of-plane stresses on the onset of localized necking. The aim of the present contribution is to propose an extension of the well-known Marciniak–Kuczynski approach to simultaneously account for the effect of curvature and normal stress on formability prediction. The new developed tool allows predicting the limit strains for the whole range of strain paths. The mechanical behavior of the studied sheets follows the rigid–plastic flow theory. Through numerical results, it is shown that both curvature and normal stress tend to increase the formability limit of the sheet metal.
KeywordsForming limit diagrams Localized necking Flow theory Out-of-plane stress Curvature Marciniak–Kuczynski approach
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- 1.Keeler SP, Backofen WA (1963) Trans ASM 56:25Google Scholar
- 2.Goodwin GM (1968) Metallurgia Italiana 60:767Google Scholar
- 4.Hutchinson JW, Neale KW, Koistinen DP, Wang NM (Eds.) (1978) Mechanics of Sheet Metal Forming. Plenum 127Google Scholar
- 10.Gotoh M, Chung T, Iwata N (1995) JSME Int J Ser A 38:123Google Scholar