Characterization of material properties of human skin is required to develop a physics-based biomechanical model that can predict deformation of female breast after cosmetic and reconstructive surgery. In this paper, we have adopted an experimental approach to characterize the biaxial response of human skin using bulge tests. Skin specimens were harvested from breast and abdominal skin of female subjects who underwent mastectomy and/or reconstruction at The University of Texas MD Anderson Cancer Center and who provided informed consent. The specimens were tested within 2 h of harvest, and after freezing for different time periods but not exceeding 6 months. Our experimental results show that storage in a freezer at −20 °C for up to about 40 days does not lead to changes in the mechanical response of the skin beyond statistical variation. Moreover, displacement at the apex of the bulged specimen versus applied pressure varies significantly between different specimens from the same subject and from different subjects. The bulge test results were used in an inverse optimization procedure in order to calibrate two different constitutive material models – the angular integration model proposed by Lanir (1983) and the generalized structure tensor formulation of Gasser et al. (2006). The material parameters were estimated through a cost function that penalized deviations of the displacement and principal curvatures at the apex. Generally, acceptable fits were obtained with both models, although the angular integration model was able to fit the curvatures slightly better than the Gasser et al. model. The range of the model parameters has been extracted for use in physics-based biomechanical models of the breast.

开发基于物理的生物力学模型需要人皮肤的材料特性，该模型可以预测整容和重建手术后女性乳房的变形。在本文中，我们采用了一种实验方法，通过凸出测试来表征人类皮肤的双轴响应。从得克萨斯大学MD安德森癌症中心接受乳房切除术和/或重建的女性受试者的乳房和腹部皮肤中收集皮肤标本，并提供知情同意。在收获后2小时内以及冷冻后的不同时间段（但不超过6个月）内对标本进行了测试。我们的实验结果表明，在-20°C的冰箱中存储最多40天不会导致皮肤机械反应的变化超出统计变化。而且，在来自同一受试者和来自不同受试者的不同试样之间，凸出的试样的顶点处的位移相对于施加的压力有显着变化。为了校准两个不同的本构材料模型– Lanir（1983）提出的角度积分模型和Gasser等人的广义结构张量公式，在反优化程序中使用了凸起测试结果。（2006）。材料参数是通过成本函数估算的，该函数对顶点处的位移和主曲率的偏差进行了惩罚。通常，尽管角积分模型能够比Gasser等人更好地拟合曲率，但两种模型都可以获得可接受的拟合。模型。