Forming Limit Evaluation with Perturbation Approach Considering Through-Thickness Normal Stress

Abstract:

To predict material’s formability in the hydroforming processes, the plane stress assumption would be invalid. The instability perturbation approach proposed by Hu et al. [1] is extended with the through-thickness normal stress by combining Hill’48 and Hosford’s yield criteria. The influences of through-thickness normal stress on the predicted forming limit strains in the forms of traditional Forming Limit Diagram (FLD) and equivalent plastic strain (EPS) based FLD (epFLD) are investigated. The results show that forming limit curves (FLCs) in both forms of FLD enhance with increasing through-thickness normal stress under proportional and non-proportional loadings. This new model can be utilized to study the effects of fluid pressure on the formability of orthotropic thin sheets.

• Periodical: Key Engineering Materials (Volume 794)
• Pages: 48-54
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.794.48
• Online since: February 2019
• Authors: Qi Hu, Xi Feng Li, Jun Chen*
• Keywords: Forming Limit, Instability Perturbation Approach, Normal Stress

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