Ultra-Thin Sheet Forming Analyses Considering Size Effects

Abstract:

Based on robust numerical formulations and various material models, finite element (FE) analysis becomes a powerful tool in conventional sheet metal forming process. Unfortunately, the present constitutive equations irrelevant to thickness that describe well conventional sheet deformation modes have difficulties being applied directly to ultra-thin sheet deformation modes. In the present study, a constitutive equation considering size effect is established by introducing a scale factor that represents size effects through thickness and width directions. Uniaxial tensile tests were used to evaluate the scale factor of different thicknesses together with the parameter identification. The developed constitutive equation reveals that thickness is the most important factor effecting on the constitutive relation of ultra-thin sheet. 2D draw forming process of C7035 ultra-thin sheet is analyzed using JSTAMP/NV introducing the developed constitutive equation. The analysis results show that there are obvious differences in the punch forces and loading geometries according to the size effect through thickness direction. Specimen width has slight effect on the flow stress although specimen thickness has strong effect on the flow stress. It is expected that the proposed constitutive equation gives good applicability to FE analysis of micro-scale forming.

• Periodical: Key Engineering Materials (Volume 794)
• Pages: 295-304
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.794.295
• Online since: February 2019
• Authors: Bon Young Ghoo*, Jun Ho Son, Yasuyoshi Umezu, Tei Hirashima, Yuko Watanabe
• Keywords: Forming Analysis, Micro Forming, Size Effect, Ultra-Thin Sheet, Uniaxial Tensile Test

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