Hashemi A, Shirazi-Adl A, Dammak M
Department of Mechanical Engineering, Ecole Polytechnique, Montreal, Quebec, Canada.
J Biomed Mater Res. 1996 Winter;33(4):257-67. doi: 10.1002/(SICI)1097-4636(199624)33:4<257::AID-JBM5>3.0.CO;2-O.
Bidirectional friction tests between cancellous bone cubes and a porous-coated metal plate were performed to determine the mechanical properties of the interface required in 3-dimensional (3-D) finite element model studies of cementless implants. Bone specimens were obtained from different proximal regions of four resurfaced cadaveric tibiae. A beaded porous-surfaced plate similar to those used in implants was used. Tangential loads in perpendicular directions with different magnitudes were applied at the interface in the presence of constant normal pressure, and the displacements were monitored in the same directions. Measured results showed that the interface load-displacement curve is highly nonlinear with significant coupling between two perpendicular directions. The interface friction coefficient (defined as the ratio of the maximum resultant tangential force divided by the normal load) was found to remain nearly unchanged with the relative magnitude of tangential stresses and the bone location. Moreover, bidirectional tests suggested that the load-displacement relation when evaluated for resultant values is similar to that obtained in a unidirectional testing condition. Constitutive equations that account for the cross-stiffness coupling terms between perpendicular directions were also developed. These relations were used in a 3-D finite element model study of preceding bidirectional friction tests. The influence of the coupling terms on results was investigated by comparison of predictions with measurement results. A satisfactory agreement was found between the results of the experiments with those of finite element studies confirming the constitutive relations as well as the importance of coupling terms.
进行了松质骨立方体与多孔涂层金属板之间的双向摩擦试验，以确定非骨水泥植入物三维（3-D）有限元模型研究中所需界面的力学性能。骨标本取自四个表面置换尸体胫骨的不同近端区域。使用了一种类似于植入物中使用的带珠多孔表面板。在恒定法向压力存在的情况下，在界面处沿垂直方向施加不同大小的切向载荷，并在相同方向上监测位移。测量结果表明，界面载荷-位移曲线高度非线性，两个垂直方向之间存在显著耦合。发现界面摩擦系数（定义为最大合成切向力除以法向载荷的比值）几乎不随切向应力的相对大小和骨位置而变化。此外，双向试验表明，当评估合成值时，载荷-位移关系与单向试验条件下获得的关系相似。还建立了考虑垂直方向之间交叉刚度耦合项的本构方程。这些关系被用于先前双向摩擦试验的三维有限元模型研究中。通过将预测结果与测量结果进行比较，研究了耦合项对结果的影响。实验结果与有限元研究结果之间发现了令人满意的一致性，证实了本构关系以及耦合项的重要性。
