A novel approach of using existing implementations of constitutive material models in any numerical codes interfacing with MFront

Abstract

Implementing a constitutive model is a long, tedious and error-prone process, in particular for soils where a wide variety of phenomena must be taken into account. Moreover, the implementation must satisfy the interface requirements of the targeted solver. MFront is a popular code generator based on C++ mostly dedicated to mechanical behaviours which provides interfaces for many academic and industrial solvers. MFront implementations also export metadata which considerably simplifies the behaviour integration in the solver, in particular if the MFrontGenericInterfaceSupport (MGIS) is used by this solver. While MFront greatly reduces the amount of work required to implement a new behaviour, existing legacy implementations are highly valuable and their re-implementation should only be considered with caution considering the trade-offs. In our experience, such a re-implementation increases the maintainability and portability, and generally the numerical performances, but requires significant development effort. In this work, we developed an alternative approach, which consists in using MFront as a wrapper to existing legacy implementations. The MFront wrapper also manages the definition of appropriate metadata and handles the transfer of the data from solver to the legacy implementation on input and output. At this stage, the approach has been used to make available all constitutive models implemented in the UMAT format (written in Fortran) in the OpenGeoSys solver which is linked to MFront via MGIS. The results of a simulation using a UMAT-model in OpenGeoSys verify the approach. The usage of MFront as a wrapper is also shown to have an insignificant/negligible impact on the numerical performance. The proposed approach opens the door to the establishment of a new database of constitutive material models in MFront where legacy implementation of existing models can be made available in all solvers interfaced with MFront. Thematic collection: This article is part of the Sustainable geological disposal and containment of radioactive waste collection available at: https://www.lyellcollection.org/topic/collections/radioactive