Fretting fatigue behaviour of Ti-6Al-4V was studied at two different contact pressures (150 MPa and 300 MPa) and two different stress ratios (0.1 and 0.7). The variation of frictional force and tangential force coefficient (TFC) with the number of fretting cycles was studied to understand the fretting fatigue behaviour of the alloy. As evidenced by the variation of frictional force with time as well as frictional force versus cyclic load hysteresis-type plots, gross sliding was present at lower contact pressures and lower stress ratios, leading to higher TFC values and surface roughness. Oxide particles were detected in the slip region and in the initiated fretting cracks indicating fretting debris. While the effect of increasing contact pressure in increasing the fretting fatigue life was clearly seen at higher stress ratio, it was not observed at lower stress ratio. At both contact pressures, a significant increase in life with an increase in stress ratio was noticed. The contact problem was analysed using the existing numerical tools to obtain the contact stresses. From these stresses, fretting fatigue lives were estimated as a sum of initiation lives estimated from multi-axial fatigue parameters and propagation lives estimated from fracture mechanics approach. A good agreement while using Findley parameter indicates that the adopted procedure can effectively account for the effects of contact pressure as well as stress ratio.

研究了Ti-6Al-4V在两种不同的接触压力（150 MPa和300 MPa）和两种不同的应力比（0.1和0.7）下的微动疲劳行为。研究了摩擦力和切向力系数（TFC）随微动循环次数的变化，以了解合金的微动疲劳行为。摩擦力随时间变化以及摩擦力与循环载荷磁滞型曲线的对比证明，在较低的接触压力和较低的应力比下会出现明显的滑动，从而导致较高的TFC值和表面粗糙度。在滑动区域和开始的微动裂纹中检测到氧化物颗粒，表明微动碎屑。在较高的应力比下，可以清楚地看到增加接触压力可以延长微动疲劳寿命，在较低的应力比下未观察到。在两种接触压力下，随着应力比的增加，寿命显着增加。使用现有的数值工具分析了接触问题，以获得接触应力。根据这些应力，微动疲劳寿命被估算为由多轴疲劳参数估算的初始寿命和由断裂力学方法估算的传播寿命的总和。使用Findley参数的良好协议表明，所采用的过程可以有效地说明接触压力以及应力比的影响。根据这些应力，微动疲劳寿命被估算为由多轴疲劳参数估算的初始寿命与由断裂力学方法估算的传播寿命的总和。使用Findley参数的良好协议表明，所采用的过程可以有效地说明接触压力以及应力比的影响。根据这些应力，微动疲劳寿命被估算为由多轴疲劳参数估算的初始寿命与由断裂力学方法估算的传播寿命的总和。使用Findley参数的良好协议表明，所采用的过程可以有效地说明接触压力以及应力比的影响。