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Abstract: Transformation
between limit strain and limit stress is evolves on the basis of plastic
relationship between strain and stress. Theoretic FLSDs (Forming limit
stress diagrams) are calculated under linear strain path, curvilinear
strain path and compounded strain path according to diffuse instability
theory, groove instability theory and plane strain floating instability
theory. The result shows that FLSD is independent of strain path, and
that the FLSD under different strain paths are almost the same curve
according to the same instability theory. So it’s more convenient and
practical to use FLSD as the criterion of forming limit.
Key
words: Sheet
metal forming FLD(Forming limit diagram) FLSD (Forming limit
stress diagram) Strain paths
CLC No: TG386
国家自然科学基金(50475004)和华中科技大学模具技术重点实验室基金(02-5)资助项目.
Received 20040109, received in revised form 20040601
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