Total knee arthroplasty (TKA) is a common procedure in the United States; it has been estimated that about 4 million people are currently living with primary knee replacement in this country. Despite huge improvements in material properties, implant design, and surgical techniques, some implants fail a few years after surgery. A lack of information about in vivo kinetics of the knee prevents the establishment of a correlated intra- and postoperative loading pattern in knee implants. In this study, a conceptual design of an ultra high molecular weight (UHMW) knee bearing with embedded piezoelectric transducers is proposed, which is able to measure the reaction forces from knee motion as well as harvest energy to power embedded electronics. A simplified geometry consisting of a disk of UHMW with a single embedded piezoelectric ceramic is used in this work to study the general parametric trends of an instrumented knee bearing. A combined finite element and electromechanical modeling framework is employed to investigate the fatigue behavior of the instrumented bearing and the electromechanical performance of the embedded piezoelectric. The model is validated through experimental testing and utilized for further parametric studies. Parametric studies consist of the investigation of the effects of several dimensional and piezoelectric material parameters on the durability of the bearing and electrical output of the transducers. Among all the parameters, it is shown that adding large fillet radii results in noticeable improvement in the fatigue life of the bearing. Additionally, the design is highly sensitive to the depth of piezoelectric pocket. Finally, using PZT-5H piezoceramics, higher voltage and slightly enhanced fatigue life is achieved.

中文翻译：

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嵌入式压电换能器全膝关节置换轴承机电及疲劳性能参数分析

全膝关节置换术 (TKA) 在美国是一种常见的手术；据估计，该国目前约有 400 万人接受初次膝关节置换术。尽管材料特性、植入物设计和手术技术有了巨大的改进，但一些植入物在手术后几年就会失败。缺乏关于膝关节体内动力学的信息阻止了在膝关节植入物中建立相关的术中和术后负荷模式。在这项研究中，提出了一种带有嵌入式压电换能器的超高分子量 (UHMW) 膝关节轴承的概念设计，该轴承能够测量膝关节运动的反作用力以及收集能量来为嵌入式电子设备供电。在这项工作中使用由 UHMW 圆盘和单个嵌入式压电陶瓷组成的简化几何结构来研究仪表膝关节轴承的一般参数趋势。结合有限元和机电建模框架用于研究仪表轴承的疲劳行为和嵌入式压电体的机电性能。该模型通过实验测试得到验证，并用于进一步的参数研究。参数研究包括调查几个维度和压电材料参数对轴承耐久性和换能器电输出的影响。在所有参数中，表明增加大圆角半径会显着提高轴承的疲劳寿命。此外，该设计对压电袋的深度高度敏感。最后，使用 PZT-5H 压电陶瓷，实现了更高的电压和略微提高的疲劳寿命。