JANCAE / material modeling working group

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Public release of UMMDp
(Unified Material Model Driver for Plasticity) library

Chairman of the UMMD Subcommittee of JANCAE
Hideo Takizawa

The Japan Association for Nonlinear CAE (JANCAE) has organized since 2001 the "Nonlinear CAE training course" since 2001, as a platform for learning systematically about nonlinear mechanics and CAE, in which many engineers and researchers have participated.

In addition to the activities, the "Rubber Working Group" was established in 2005 to promote more practical activities concerning issues related to viscoelastic and hyper-elastic material models. This working group was renamed as "Material Modeling Working Group" in 2008, to extend the subject for general nonlinear material model including metals and resins, and continued its activities until 2016 with cooperation of numerous participants. Currently, these activities have been transferred to the "Modeling and Simulation practice working group" where the framework has been extended furthermore.

There are many issues that need to be considered in improving the accuracy of nonlinear structural analysis. In particular, on the issue of how to incorporate in the analyses the complex behavior of materials handled in practice, various material models are being proposed since there is no right answer based on principles of mathematics and mechanics.

In the "Material Modeling Working Group," the participants learned the basic idea of how to deal with material models in nonlinear structural analysis, and as its practical application, worked on using various material models proposed by numerous researchers, utilizing the user subroutine function available in commercial codes. The UMMDp, released publicly here, is the "user-subroutine library for various anisotropic yield functions" that has been developed by the participants of the working group.

Until now, UMMDp has been shared among the members of the working group, however, based on the philosophy of JANCAE, which is a non-profit organization, UMMDp is now being made available for public use.Please note that, there is no guarantee that the package will always work properly and correct answers will be obtained. Please also note that the library usage responsibility and accountability lie with the users.

We hope that through this public release, more users will get involved in non-linear structural analysis.

Last of all, we want to thank all the participants of the working group, especially, the engineers and researchers who contributed to the UMMDp working group activities. We also want to express our gratitude to the association staff for their help in conducting the working group activities.