W.M. Keck Biomedical Materials Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA.
J Mech Behav Biomed Mater. 2012 Sep;13:62-8. doi: 10.1016/j.jmbbm.2012.04.010. Epub 2012 Apr 24.
Porous metals are being widely used in load bearing implant applications with an aim to increase osseointegration and also to reduce stress shielding. However, fatigue performance of porous metals is extremely important to ensure long-term implant stability, because porous metals are sensitive to crack propagation even at low stresses especially under cyclic loading conditions. Herein we report high-cycle compression-compression fatigue behavior of laser processed NiTi alloy with varying porosities between ∼1% and 20%. The results show that compression fatigue of porous NiTi alloy samples is in part similar to metal foams. The applied stress amplitude is found to have strong influence on the accumulated strain and cyclic stability. The critical stress amplitudes associated with rapid strain accumulation in porous NiTi alloy samples, with varying relative densities, were found to correspond to 140% of respective 0.2% proof strength indicating that these samples can sustain cyclic compression fatigue stresses up to 1.4 times their yield strength without failure.
多孔金属被广泛应用于承重植入物应用中，旨在提高骨整合性并降低应力屏蔽。然而，多孔金属的疲劳性能对于确保长期植入物稳定性非常重要，因为多孔金属即使在低应力下，特别是在循环加载条件下，也容易受到裂纹扩展的影响。本文报道了具有 1%-20%不同孔隙率的激光加工 NiTi 合金的高周压缩-压缩疲劳行为。结果表明，多孔 NiTi 合金样品的压缩疲劳在一定程度上类似于金属泡沫。发现施加的应力幅对累积应变和循环稳定性有很强的影响。与不同相对密度的多孔 NiTi 合金样品中快速应变积累相关的临界应力幅被发现对应于各自 0.2%屈服强度的 140%，这表明这些样品可以在不失效的情况下承受高达其屈服强度 1.4 倍的循环压缩疲劳应力。
