Material Properties and Constitutive Modeling of Infant Porcine Cerebellum Tissue in Tension at High Strain Rate

BACKGROUND: The mechanical characterization of infant porcine cerebellum tissue in tension at high strain rate is crucial for modeling traumatic cerebellum injury, which is in turn helpful for understanding the biomechanics of such injuries suffered in traffic accidents. MATERIAL AND METHOD: In this study, the infant porcine cerebellum tissue was given three loading velocities, ie, 2s(-1), 20s(-1) and 100s(-1) with up to 30% strain to investigate the tensile properties. At least six tensile tests for each strain rate were validly performed. Fung, Gent, Ogden and exponential models were applied to fit the constitutive equations, so as to obtain material parameters from the experimental data. RESULTS: The Lagrange stress of infant porcine cerebellum tissue in tension appeared to be no more than 3000Pa at each loading velocity. More specifically, the Lagrange stress at 30% strain was (393.7±84.4)Pa, (928.3±56.3)Pa and (2582.4±282.2)Pa at strain rates of 2s(-1), 20s(-1) and 100s(-1), respectively. Fung (0.833≤R(2)≤0.924), Gent (0.797≤R(2)≤0.875), Ogden (0.859≤R(2)≤0.944) and exponential (0.930≤R(2)≤0.972) models provided excellent fitting to experimental data up to 30% strain. CONCLUSIONS: The infant cerebellum tissue shows a stiffer response with increase of the loading speed, indicating a strong strain-rate sensitivity. This study will enrich the knowledge on the material properties of infant brain tissue, which may augment the biofidelity of finite element model of human pediatric cerebellum.