Calculation of parameters of elastic and hyperelastic facial skin models

The results of uniaxial mechanical tests of the facial (forehead) skin in vitro were compared with linear, bilinear and non-linear exponential, as well as five hyperelastic models. The results showed that the deformation properties of tissues are best described by the exponential function. Linear and bilinear elastic models are considered and the numerical values of the model parameters are determined. To study the hyperelastic properties of the skin, neohookean, Mooney – Rivlin, Ogden, polynomial and Veronda – Westmann phenomenological models were used. In order to find the most advanced algorithms for calculating the parameters of hyperelastic models, calculations were performed in the Mathcad 15 computer algebra system and the Ansys 2022 R2 multi-purpose software package. The parameters of the models and the closeness of the correlation between the exponential curve and the calculated data were determined, the correlation coefficient was used as a criterion for the correspondence of the models. The polynomial model and the Ogden model demonstrated the highest correlation with the experimental values, and the neohookean one demonstrated the lowest correlation. The values of Young's moduli and other elastic and hyperelastic characteristics of tissues were compared to study the factors affecting the mechanical behavior of human facial skin, and can be used in calculations in finite element analysis and in the development of replacement materials for plastic surgery.