Identifying the dynamic compressive stiffness of a prospective biomimetic elastomer by an inverse method

• Published in: Journal of the mechanical behavior of biomedical materials 2012-10, Vol.14, p.89-100
• Main Authors: Mates, Steven P., Forster, Aaron M., Hunston, Donald, Rhorer, Richard, Everett, Richard K., Simmonds, Kirth E., Bagchi, Amit
• Format: Article
• Language: English
• Subjects: Biomimetic material; Biomimetic Materials; Compressive Strength; Digital image correlation; Dynamic response; Dynamics; Elastomers; Finite Element Analysis; Friction; High-strain-rate; Imaging, Three-Dimensional; Inverse method; Inverse problem; Kolsky bar; Materials Testing - instrumentation; Materials Testing - methods; Mathematical models; Mechanical properties; Strain; Stress strain curves; Stress, Mechanical; Uncertainty
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2012.04.023

Soft elastomeric materials that mimic real soft human tissues are sought to provide realistic experimental devices to simulate the human body's response to blast loading to aid the development of more effective protective equipment. The dynamic mechanical behavior of these materials is often measured using a Kolsky bar because it can achieve both the high strain rates (>100s−1) and the large strains (>20%) that prevail in blast scenarios. Obtaining valid results is challenging, however, due to poor dynamic equilibrium, friction, and inertial effects. To avoid these difficulties, an inverse method was employed to determine the dynamic response of a soft, prospective biomimetic elastomer using Kolsky bar tests coupled with high-speed 3D digital image correlation. Individual tests were modeled using finite elements, and the dynamic stiffness of the elastomer was identified by matching the simulation results with test data using numerical optimization. Using this method, the average dynamic response was found to be nearly equivalent to the quasi-static response measured with stress–strain curves at compressive strains up to 60%, with an uncertainty of ±18%. Moreover, the behavior was consistent with the results in stress relaxation experiments and oscillatory tests although the latter were performed at lower strain levels. [Display omitted] ► We identify the dynamic compressive response of a prospective soft-tissue-simulating elastomer using an inverse method. ► Finite element modeling combines with high-speed digital image correlation to identify the dynamic stiffness. ► The method eliminates measurement errors due to specimen inertia and friction effects. ► This elastomer's stiffness was unchanged over the six decades in strain rate examined.