The objective of this work is to characterize and to model the damage of planar and fibrous soft tissues at high strain rate. As first step, human skin was studied. A dynamic tensile test up to failure is performed on 10x30mm human skin samples. The test is based on the drop test principle and allows loading of samples at a strain rate close to 40/s. Classical measurement techniques give global strains whereas a full local strain field is measured on the sample surface by an image correlation method . The behavior of the skin is simulated using a collagen fiber network defined by an angular distribution of fibers. This model is extended to the damage phase by using a brittle hyper elastic behavior for the fibers. The skin seems stiffer in the transverse direction than in the cranio-caudal direction andthe strain field measurements show the heterogeneity of the tissue. First, the model parameters are identified on a representative experimental curve obtained for the human forehead skin in the transverse direction. Othernumerical validations show that the numerical model is able to reproduce the anisotropy of the skin, its heterogeneity and its damage up to failure. In conclusion, the model of planar and fibrous soft tissues, based on a structural approach, reproduces well the real hyper elastic behavior and the damage mechanisms of the skin. A next step will be the definition of anoptimization method for the identification of the model parameters by comparing numerical and experimental results. For the covering abstract see ITRD E141762.
Abstract