Fracture prediction in metal sheets

One of the most important failure modes of thin-walled structures is fracture. Fracture is predominantly tensile in nature and, in most part, is operated by the physical mechanisms of void nucleation, growth, and linkage. For ductile sheet, fracture is preceded by necking. Prediction of necking which limits sheet metal formability is well established and has been developed over the past several decades. However, an in-depth understanding of the mechanical process inside the neck leading to sheet metal fracture is lacking. This is true for both static and high intensity, short duration loads. Furthermore, there is an ever increasing need to raise the safety envelope of existing protective structures against localized extreme loading. The present thesis addresses four parts of the many outstanding issues in sheet metal fracture. In the first part, the new Bao-Wierzbicki (BW) fracture criterion formulated in terms of the accumulated equivalent plastic strain with the stress triaxiality as a weighting function is considered. Using the equations of plane stress von-Mises plasticity and the strain-to-stress mapping procedure, the BW fracture criterion is transformed to the spaces of the principal tensile strains and stresses in a sheet and compared with experimental results for various materials. An extensive comparative study of the most widely used fracture criteria is then conducted.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Ocean Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Lee, Young-Woong

Advisor dc:contributor.advisor

• Tomasz Wierzbicki.

• Ocean Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/33560

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33560