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Development and Application of Non-linear Friction Models for Metal Forming Simulation
Ninshu Ma,Nobuhiko Sugitomo 한국소성가공학회 2011 기타자료 Vol.2011 No.8
Friction has a significant effect on the formability of stamping parts. A constant friction coefficient between stamping tools and blank is often employed in the metal forming simulating. In this presented work, several non-linear friction models which considers of the change of friction coefficient with contact pressure, sliding velocity, sliding distance, frictional work, plastic strain and temperature were developed using LS-DYNA customized friction subroutine. The validity was verified by numerical friction testing models and deep drawing model.
An Optimization Study of Hot Stamping Operation
Bonyoung Ghoo,Yasuyoshi Umezu,Yuko Watanabe,Ninshu Ma,Ron Averill 한국소성가공학회 2010 기타자료 Vol.2010 No.6
In the present study, 3-dimensional finite element analyses for hot-stamping processes of Audi B-pillar product are conducted using JSTAMP/NV and HEEDS. Special attention is paid to the optimization of simulation technology coupling with thermal-mechanical formulations. Numerical simulation based on FEM technology and optimization design using the hybrid adaptive SHERPA algorithm are applied to hot stamping operation to improve productivity. The robustness of the SHERPA algorithm is found through the results of the benchmark example. The SHERPA algorithm is shown to be far superior to the GA (Genetic Algorithm) in terms of efficiency, whose calculation time is about 7 times faster than that of the GA. The SHERPA algorithm could show high performance in a large scale problem having complicated design space and long calculation time.
Song Wu,Leitao Gao,Yusuke Matsuoka,Sherif Rashed,Yixi Zhao,Ninshu Ma 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4
Incremental sheet forming (ISF) is a die-less manufacturing technology suitable for small lot and/or customized parts. However, geometric accuracy issues in ISF with a singlestep toolpath and a conventional multi-step toolpath, such as the pillow and stepped feature at the base areas of manufactured parts, limit the industrial application of this technology. This study presents a novel parametric multi-step toolpath that uses one additional step to form a non-axisymmetric component with the Al2024 sheet. An acceptable higher geometry accuracy below ± 0.6 mm can be obtained experimentally and numerically by adjusting the influencing factors of the multi-step toolpath. Then, the material motion and the strain path in the forming of the non-axisymmetric component with different multi-step toolpaths is analyzed. Results indicate that the flat base depends on the rigid body motion in the central base area and the strain increment balance between the base and sidewall.