Implementation and validation of the extended Hill-type muscle model with robust routing capabilities in LS-DYNA for active human body models

Christian Kleinbach,Daniel F B Haeufle,Jörg Fehr,Oleksandr Martynenko,Syn Schmitt,Janik Promies

doi:10.1186/s12938-017-0399-7

Abstract

BackgroundIn the state of the art finite element AHBMs for car crash analysis in the LS-DYNA software material named *MAT_MUSCLE (*MAT_156) is used for active muscles modeling. It has three elements in parallel configuration, which has several major drawbacks: restraint approximation of the physical reality, complicated parameterization and absence of the integrated activation dynamics. This study presents implementation of the extended four element Hill-type muscle model with serial damping and eccentric force–velocity relation including Ca^{2+} dependent activation dynamics and internal method for physiological muscle routing.ResultsProposed model was implemented into the general-purpose finite element (FE) simulation software LSDYNA as a user material for truss elements. This material model is verified and validated with three different sets of mammalian experimental data, taken from the literature. It is compared to the *MAT_MUSCLE (*MAT_156) Hill-type muscle model already existing in LS-DYNA, which is currently used in finite element human body models (HBMs). An application example with an arm model extracted from the FE ViVA OpenHBM is given, taking into account physiological muscle paths.ConclusionThe simulation results show better material model accuracy, calculation robustness and improved muscle routing capability compared to *MAT_156. The FORTRAN source code for the user material subroutine dyn21.f and the muscle parameters for all simulations, conducted in the study, are given at https://zenodo.org/record/826209 under an open source license. This enables a quick application of the proposed material model in LS-DYNA, especially in active human body models (AHBMs) for applications in automotive safety.

Highlights

In the state of the art finite element active human body models (AHBMs) for car crash analysis in the LS-DYNA software material named *MAT_MUSCLE (*MAT_156) is used for active muscles modeling
The FORTRAN source code for the user material subroutine dyn21.f and the muscle parameters for all simulations, conducted in the study, are given at https://zenodo. org/record/826209 under an open source license. This enables a quick application of the proposed material model in LS-DYNA, especially in active human body models (AHBMs) for applications in automotive safety
In the publication of Haeufle et al [25], a modified Hill-type muscle model was proposed with improved serial damping and eccentric force-velocity relation. This model consists of four simple mechanical elements: an active contractile element (CE), which is controlled by the activation level q; parallel (PEE) and serial (SEE) nonlinear spring elements and a serial damping element (SDE)

Summary

Introduction

In the state of the art finite element AHBMs for car crash analysis in the LS-DYNA software material named *MAT_MUSCLE (*MAT_156) is used for active muscles modeling. It has three elements in parallel configuration, which has several major drawbacks: restraint approximation of the physical reality, complicated parameterization and absence of the integrated activation dynamics. It is hard to imagine that the development of modern vehicles can be done without wide utilization of computer aided engineering (CAE), including state-of-the-art numerical simulations software. These tools offer opportunities to the car manufacturers. Joint simulations with a combined application of car and human body models allow for prediction of in-crash behaviour and possible injuries for occupants or pedestrians with a sufficient accuracy throughout all stages in development, replacing expensive crash tests using car prototypes and Anthropomorphic Test Devices (ATDs)

Methods

Results

Conclusion