Hubei Provincial Key Laboratory of Chemical Equipment Intensification and Intrinsic Safety, School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan, 430205, P. R. China.
J Mater Sci Mater Med. 2019 Apr 19;30(5):50. doi: 10.1007/s10856-019-6254-6.
The mechanical properties of medical grade ultrahigh molecular weight polyethylene (UHMWPE) are critical for the safety and integrity of UHMWPE implantation. Accordingly, the mechanical features of UHMWPE are tested under repeated stress-controlled and strain-controlled compression at room temperature. Some important effect factors, such as stress rate, mean stress, stress amplitude, strain rate, mean strain, strain range and multiple load steps are further considered in detail. Results indicate that the lower stress rate causes the greater accumulated plastic strain and the accumulated plastic strain rate becomes increasingly lower with increasing number of cycles. The strain range and accumulated plastic strain rate decrease rapidly in the first stage, and then become almost steady during the second stage. Especially, the accumulated plastic strain rate per cycle for each case is less than 0.01 %/cycle after the initial 100 cycles. This means that the plastic strain accumulates very slowly and the shakedown behavior always occurs. Moreover, obvious cyclic softening and stress relaxation behaviors can be observed under cyclic strain-controlled compression during the first 50 cycles. This indicates that the accumulated plastic stain in the initial 100 cycles and the cyclic stress relaxation during the first 50 cycles should be assessed for the functionality of UHMWPE implantation.
医用超高相对分子量聚乙烯（UHMWPE）的力学性能对于其植入的安全性和完整性至关重要。因此，UHMWPE 的力学性能在室温下经过反复的应力控制和应变控制压缩测试来进行评估。进一步详细考虑了一些重要的影响因素，如应力速率、平均应力、应力幅度、应变速率、平均应变、应变范围和多步加载。结果表明，较低的应力速率会导致更大的累积塑性应变，并且随着循环次数的增加，累积塑性应变率逐渐降低。在第一阶段，应变范围和累积塑性应变率迅速下降，然后在第二阶段几乎稳定。特别是，在初始 100 个循环后，每个情况下每个循环的累积塑性应变率都小于 0.01 %/cycle。这意味着塑性应变积累非常缓慢，并且总是会出现安定现象。此外，在最初的 50 个循环中，在循环应变控制压缩下可以观察到明显的循环软化和应力松弛行为。这表明在最初的 100 个循环中的累积塑性应变和最初 50 个循环中的循环应力松弛都应该对 UHMWPE 植入的功能进行评估。
