A Partitioned Coupling Approach for Electromechanics Simulations of Skeletal Muscles Using FEBio

This work presents a partitioned coupling approach for electromechanical simulations of skeletal muscles. For the first time, we couple our highly specialized electrophysiology solver, which computes both force generation in muscle cells and action potential propagation in muscle fibers, with an external finite element continuum mechanics solver. In particular, we couple an OpenDiHu electrophysiology solver with an FEBio mechanics solver using the coupling library preCICE. Thereby, we present the FEBio adapter and a customized FEBio material, enabling multi‐scale, multi‐physics simulations using a coupled OpenDiHu‐FEBio approach, and incorporating more complex excitation–contraction dynamics and spatial inhomogeneity than in a standard FEBio simulation. We test the OpenDiHu‐FEBio approach on two muscle geometries and compare it to the existing coupled OpenDiHu–OpenDiHu approach, showing that the OpenDiHu–FEBio approach is faster. Besides, we show that preCICE's coupling overhead is small compared to the simulation's total runtime, even when complex, expensive data mapping methods between OpenDiHu and FEBio are used. Using FEBio instead of the OpenDiHu mechanics solver has additional advantages, including support for unstructured grids, multiple well‐established, verified, and tested material models, and an extensive user community. All in all, the implemented OpenDiHu‐FEBio approach shows how we can combine highly application‐specific muscle software with more general tools in a flexible, efficient way, and is a step forward for future development of application‐specific muscle simulations.