Zhang M, Lord M, Turner-Smith A R, Roberts V C
Department of Medical Engineering & Physics, King's College School of Medicine & Dentistry, Denmark Hill, London, UK.
Med Eng Phys. 1995 Dec;17(8):559-66. doi: 10.1016/1350-4533(95)00002-5.
A non-linear finite element model has been established to predict the pressure and shear stress distribution at the limb-socket interface in below-knee amputees with consideration of the skin-liner interface friction and slip. In this model, the limb tissue and socket liner were respectively meshed into 954 and 450 three-dimensional eight-node isoparametric brick elements, based on measurements of an individual's amputated limb surface; the bone was meshed into three-dimensional six-node triangular prism elements, based on radiographic measurements of the individual's residual limb. The socket shell was assumed to be a rigid boundary. An important feature of this model is the use of 450 interface elements (ABAQUS INTER4) which mimic the interface friction condition. The results indicate that a maximum pressure of 226 kPa, shear stress of 53 kPa and less than 4 mm slip exist at the skin-liner interface when the full body weight of 800 N is applied to the limb. The results also show that the coefficient of friction is a very sensitive parameter in determining the interface pressures, shear stresses and slip. With the growth of coefficient of friction, the shear stresses will increase, while the pressure and slip will decrease.
已建立一个非线性有限元模型，用于预测考虑皮肤 - 内衬界面摩擦和滑动的膝下截肢者肢体 - 接受腔界面处的压力和剪应力分布。在该模型中，基于个体截肢肢体表面的测量数据，将肢体组织和接受腔内衬分别划分为954个和450个三维八节点等参砖单元；基于个体残肢的X射线测量数据，将骨骼划分为三维六节点三棱柱单元。接受腔外壳被假定为刚性边界。该模型的一个重要特征是使用450个界面单元（ABAQUS INTER4）来模拟界面摩擦条件。结果表明，当800 N的全身重量施加于肢体时，皮肤 - 内衬界面处存在226 kPa的最大压力、53 kPa的剪应力以及小于4 mm的滑动。结果还表明，摩擦系数是确定界面压力、剪应力和滑动的一个非常敏感的参数。随着摩擦系数的增大，剪应力将增加，而压力和滑动将减小。
