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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/100/1839

Title: A novel criterion for predicting forming limit strains
Authors: NARASIMHAN, K
Issue Date: 2004
Publisher: AMER INST PHYSICS
Citation: MATERIALS PROCESSING AND DESIGN: MODELING, SIMULATION AND APPLICATIONS, PTS 1 AND 2,712,850-855
Abstract: During sheet metal forming, the useful shape change is limited by necking/splitting type failures. The maximum surface strains that can be achieved before the onset of necking/splitting are defined as limit strains. The limit strains depend strongly on the quality of the sheet metal (mechanical properties) and the strain path of the deformation. During forming simulation, it is essential to have a failure criterion for predicting the limit strains. In order to improve our capability to predict forming severity and limit strains during stamping of industrial sheet metal parts, a novel failure criterion for measuring / predicting onset of necking is proposed. The criterion is based on the development of thickness gradients across neighboring regions of a deforming sheet metal. The proposed criterion simply states that when the ratio of thickness in neighboring regions of a deforming sheet metal drops below a critical magnitude, necking develops. The proposed criterion does not depend on the sheet metal quality as well as the strain path. The critical magnitude of the thickness ratio for onset of necking is established by systematic, incremental tensile testing of sheet metal samples. The magnitude is found to be about 0.92. The proposed criterion is validated extensively for different strain paths, both for in-plane stretching and out-of-plane stretching conditions in drawing quality steel sheets. Using the proposed criterion, it was possible to accurately predict the base line FLD of a drawing quality steel sheet. The criterion provides an alternative way of assessing forming severity for industrial sheet metal components.
URI: http://dspace.library.iitb.ac.in/xmlui/handle/10054/15091
http://hdl.handle.net/100/1839
ISBN: 0-7354-0188-8
ISSN: 0094-243X
Appears in Collections:Proceedings papers

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