JANCAE / material modeling working group

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Public release of UMMD
(Unified Material Model Driver ) library

Chairman of the UMMD Subcommittee of JANCAE
Hideo Takizawa

The Japan Association for Nonlinear CAE (JANCAE) has organized 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 hyperelastic material models. This working group was renamed as "Material Modeling Working Group" in 2008, to extend the subject for general nonlinear material models including metals and resins, and continued its activities until 2016 with the 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.

These programs have been designed to be used with any type of commercial FEM code and have been developed as the UMMDx (Unified Material Model Driver for X) series.

Until now, UMMDx has been shared among the members of the working group, however, based on the philosophy of JANCAE, which is a non-profit organization, following UMMDx libraries are available for public use.
  UMMDp (Plasticity): User subroutine library for various anisotropic yield functions (2018/07 public release)
  UMMDr (Rubber): User subroutine library of hyperelasticity, damage, and viscoelasticity for rubber-like material (2022/07 public release)

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 nonlinear structural analysis.

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

[Received the "The Technology Prize" from the Japan Society for Computational Engineering and Science]
  Hideo TAKIZAWA, chairman of the UMMD Committee, and Takashi TERAJIMA, a member of the UMMD Committee, received the Technology Prize from the Japan Society for Computational Engineering and Science in 2018 for the development and release of the UMMD.
  Once again, we would like to express our gratitude to everyone who participated in this project.