仿生织构表面对人工髋关节副动压润滑性能及减摩性分析

Analysis of Biomimetic Texture Surface on Dynamic Compression Lubrication and Friction Reduction of Artificial Hip Pair

为提高钛合金TC4人工髋关节假体的耐磨性,从仿生学角度在钛合金关节表面设计出菱形织构。基于雷诺方程建立织构化关节表面流体动压润滑数学模型,采用有限差分法对其进行离散,通过Matlab编程进行迭代求解,获取织构表面的润滑油膜压力分布以及织构化关节表面的摩擦因数,分析织构几何参数(菱形织构对角线长度b和织构深度hp)对摩擦性能的影响规律。加工钛合金销-盘摩擦副,用激光在盘试样上加工出菱形织构,并在牛血清润滑状态下以及相同载荷和转速的条件下进行摩擦磨损试验。结果表明:随着菱形织构参数b和织构深度hp的增加,摩擦因数呈先增加后减小的趋势。并且试验结果与数值仿真结果具有较高的一致性,在菱形织构参数b为447μm,织构深度hp为10μm,存在最小摩擦因数为0.14。微织构的存在可以实现流体动压润滑,提高关节副的承载力,降低摩擦因数,从而改善关节副的摩擦性能。该研究为提高人工髋关节的寿命提供理论依据。

In order to improve the wear resistance of the titanium alloy TC4 artificial hip joint prosthesis,a diamond texture was designed on the surface of the titanium alloy joint from the perspective of bionics.Based on the Reynolds equation,a mathematical model of hydrodynamic lubrication of the textured joint surface is established.Applying the finite difference method to discretize the model,and the oil film pressure distribution and friction coefficient on the textured joint surface is obtained by Matlab programming.The influence of texture geometric parameters(diamond diagonal length b and depth hp)on friction performance is analyzed.The titanium alloy pin-disc friction pair was machined,first.Then the diamond texture was machined on the disc sample by laser.Finally,the friction and wear test are carried out under the condition of bovine serum lubrication and the same load and rotational speed.The results show that with the increase of diamond texture parameter b and depth hp,the friction coefficient first increases and then decreases;the test results have a high consistency with the numerical simulation results;the texture parameter b is 447μm,the texture depth hp is 10μm,and the minimum friction coefficient is 0.14.The existence of diamond texture can realize fluid dynamic pressure lubrication on the surface of joint pair,improve the bearing capacity of the joint pair,reduce the friction coefficient,and thus improve the friction performance of the joint pair.This study provides the theoretical basis for improving the life of artificial hip joint.