Title: An algorithm for localised and diffuse necking analysis

Authors: Juri Majak, Meelis Pohlak, Rein Kuttner

Addresses: Mechanics Department, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia. ' Mechanics Department, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia. ' Mechanics Department, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia

Abstract: An analysis of localised and diffuse necking in orthotropic sheet metals is performed. Numerical algorithm covering different yield criteria and strain hardening laws is developed. The numerical algorithm proposed is based on plastic instability criterion derived in tensor notation. The capabilities of the instability criteria derived are improved using different anisotropic yield criteria and strain hardening laws. The obtained results are validated against experimental test results and compared with the results available in literature. The material parameters identification procedure for advanced yield criterion BBC2003 is treated. The Computer Algebra Systems (CAS-es) method is employed for material parameters identification. Simplicity and low computational cost of numerical analysis is achieved by the use of Hill and Swift instability conditions and empirical stress-strain relation. [Received 7 March 2007; Accepted 10 July 2007]

Keywords: strain hardening; stress; FLD; BBC2003; material parameters identification; computer algebra systems method; CAS-es; necking analysis; orthotropic sheet metals; plastic instability; failure prediction; sheet metal forming; forming limit diagram.

DOI: 10.1504/IJCMSSE.2007.016438

International Journal of Computational Materials Science and Surface Engineering, 2007 Vol.1 No.4, pp.494 - 508

Published online: 28 Dec 2007 *

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