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A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials
Published on: May 18, 2015
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How to implement user-defined fiber-reinforced hyperelastic materials in finite element software
Heleen Fehervary1, Lauranne Maes1, Julie Vastmans1
1Biomechanics Section, Mechanical Engineering Department, KU Leuven, Leuven, Belgium.
Journal of the Mechanical Behavior of Biomedical Materials
|August 11, 2020
Summary
Implementing custom material models in finite element analysis for biomechanics is crucial for accurate simulations. This study details user subroutine implementations in Abaqus, offering a valuable resource for biomedical engineers.
Area of Science:
- Biomechanical Engineering
- Computational Mechanics
- Materials Science
Background:
- Finite element modeling (FEM) is vital for evaluating medical devices and treatments.
- Accurate material models are essential for reliable biomechanical simulations.
- Pre-programmed material models in FEM software often lack flexibility, necessitating custom implementations.
Purpose of the Study:
- To provide a detailed guide for implementing nonlinear hyperelastic material models using user subroutines in Abaqus.
- To compare different implementation strategies and element formulations for biomechanical simulations.
Main Methods:
- Implementation of the Gasser-Ogden-Holzapfel material model using Abaqus user subroutines (UANISOHYPER_INV and UMAT).
- Comparison of built-in, UANISOHYPER_INV, and UMAT (analytical and numerical tangent stiffness) formulations.
- Verification using single-element tests and an extension-inflation experiment with multiple elements and non-homogeneous deformations.
- Analysis of stresses, displacements, reaction forces, iterations, and CPU time across different element formulations (continuum compressible, continuum incompressible, plane stress incompressible).
Main Results:
- All four implementation variations demonstrated high accuracy, with relative errors between 10^-3 and 10^-15.
- The number of iterations required varied by a maximum of one across implementations.
- CPU times were comparable across the different user subroutine approaches.
- User subroutines offer a viable and accurate alternative to built-in material models.
Conclusions:
- User subroutines in Abaqus provide a flexible and accurate method for implementing custom hyperelastic material models in biomechanical engineering.
- The provided tutorial and supplementary code serve as a practical starting point for engineers developing their own material models.
- This work facilitates more reliable and sophisticated simulations of biological tissues and medical devices.
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