Title: Sheet metals forming limit stress and strain prediction based on new generalised yield criterion
Authors: R. Ponalagusamy; R. Narayanasamy; K.R. Subramanian
Addresses: Department of Mathematics, National Institute of Technology, Tiruchirappalli-620-015, Tamil Nadu, India. ' Department of Production Engineering, National Institute of Technology, Tiruchirappalli-620-015, Tamil Nadu, India. ' Department of Mathematics and Computer Applications, Srimathi Indira Gandhi College, Tiruchirappalli-620-002, Tamil Nadu, India
Abstract: A new form of yield theory considering an anisotropic parameter for sheet metals has been derived and proposed in this technical paper. In addition to this, the flow rule with anisotropic parameter for sheet metals is introduced. The mathematical expression for the calculation of flow stress in the case of simple compression-tension, tension-tension test is deduced from the yield theory for the sheet metals. The developed yield theory is used for obtaining the mathematical expressions of their limit strains in connection with the swift's plastic instability condition for diffuse necking and the Hill's plastic instability condition for localised necking. Using the flow rule and the experimental parameters, the forming limit curves for the various sheet metals using sheet metal parameters namely the shape of the yield curve (m-value) and relative density, have been obtained. It has been particularly found that the FLC curve is affected by the relative density (R-value) and yield criterion constant (m-value).
Keywords: generalised yield criteria; anisotropic parameters; forming limit stress curve; FLSC; forming limit diagram; FLD; sheet metal forming.
International Journal of Computational Materials Science and Surface Engineering, 2011 Vol.4 No.4, pp.311 - 325
Received: 23 Jul 2010
Accepted: 08 Jul 2011
Published online: 23 Feb 2012 *