Characterization of viscoelastic properties of the human thigh skin can be utilized in many medical or engineering applications such as a surgical extension of the thigh skin, a tissue engineering, and a finite element modeling of thigh skin in a sitting posture. This study aims to determine the effective short- and long-term shear moduli of posterior thigh skin using ramp-relaxation test in a sitting posture. The effect of indentation location, the sitting posture, and the applied load (thigh weight) were investigated on the extracted effective shear moduli. We modeled the human skin by using the one- and two-term Prony series, and it was found that the generalized Maxwell model with two-term Prony series agreed well with experimental data. The effective shear moduli (short- and long-term) were extracted by fitting the total reaction force of the generalized Maxwell model to the experimental data using the Levenberg-Marquardt algorithm. The contour maps were used to show the spatial dependency of the effective shear moduli at the flat regions of posterior thigh skin. The contour maps of effective shear moduli show that maximum effective shear moduli locate near buttock’s center, while minimum effective shear moduli locate at the distal and medial posterior thigh. It is also found that the extracted effective short-term shear modulus varies between 3978.2 N/m² and 13699.2 N/m². On the other hand, the extracted effective long-term shear modulus differs between 2715.1 N/m² and 9194.3 N/m² for different sitting postures. Additionally, it is found that the observed increase in effective shear moduli could be attributed to the increase applied load, and leg angle.

中文翻译：

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使用坡道松弛压痕测试表征体内人大腿后部皮肤的粘弹性模型

人大腿皮肤的粘弹性特性的表征可用于许多医学或工程应用中，例如大腿皮肤的外科手术扩展，组织工程学和坐姿的大腿皮肤的有限元建模。这项研究的目的是在坐姿下使用坡道放松试验确定大腿后部皮肤的有效短期和长期剪切模量。研究了压痕位置，坐姿和施加的载荷（大腿重量）对提取的有效剪切模量的影响。我们使用一阶和二阶Prony级数对人体皮肤进行建模，发现带有二项Prony级数的广义Maxwell模型与实验数据吻合良好。通过使用Levenberg-Marquardt算法将广义Maxwell模型的总反作用力拟合到实验数据，可以提取有效剪切模量（短期和长期）。等高线图用于显示大腿后部皮肤平坦区域有效剪切模量的空间依赖性。有效剪切模量的等高线图显示，最大有效剪切模量位于臀部的中心附近，而最小有效剪切模量位于大腿的远端和内侧。还发现提取的有效短期剪切模量在3978.2 N / m之间变化 有效剪切模量的等高线图显示，最大有效剪切模量位于臀部的中心附近，而最小有效剪切模量位于大腿的远端和内侧。还发现提取的有效短期剪切模量在3978.2 N / m之间变化 有效剪切模量的等高线图显示，最大有效剪切模量位于臀部的中心附近，而最小有效剪切模量位于大腿的远端和内侧。还发现提取的有效短期剪切模量在3978.2 N / m之间变化²和13699.2 N / m ²。另一方面，对于不同的坐姿，提取的有效长期剪切模量在2715.1 N / m ²和9194.3 N / m ^2之间。另外，发现观察到的有效剪切模量的增加可归因于所施加的载荷和腿角度的增加。