定、变载弯曲疲劳钢丝绳失效机理对比研究

Comparative Research on Failure Mechanisms of Steel Wire Ropes during Bending Fatigue under Constant and Variable Loads

为对比揭示定、变载弯曲疲劳钢丝绳断裂机理及磨损演化特性,运用自制钢丝绳弯曲疲劳试验机开展钢丝绳定载、变载弯曲疲劳试验,通过人工拆股统计法和VW-9000系列高速度数码显微系统对比研究钢丝绳断丝分布、断丝数、断口和磨痕形貌等断裂机理,对比分析钢丝绳未断钢丝和断丝的磨痕尺寸演化特性.结果表明:与钢丝绳定载弯曲疲劳相比,变载弯曲疲劳钢丝绳断丝出现较晚,芯股、螺旋股外层断丝数分别较多、较少,芯股外层钢丝断口挤压变形较大,芯股各层钢丝断口裂纹扩展区占比较低,芯股和螺旋股的各层钢丝磨痕尺寸总体较小,钢丝绳更易达到报废水平.

In order to comparatively reveal fracture mechanisms and wear evolution characteristics of steel wire ropes during bending fatigue under constant and variable loads,the self-made bending fatigue test rig of steel wire rope was employed to carry out bending fatigue tests of steel wire ropes under constant and variable loads.The statistical method by disassembling strands manually and VW-9000 series high-speed digital micro system were employed to comparatively investigate distributions and number of fractured wires,morphologies of fractures and wear scars at fractures of steel wires,evolutions of wear scar dimensions of unfractured and fractured wires in the rope.The results showed that as compared to bending fatigue of steel wire rope under the constant load,the bending fatigue of steel wire rope under the variable load presented later occurrences of fractured wires,more and fewer fractured wires in the outer layers of core and outer strands,respectively,larger extrusion deformations at fractures of outer layer wires in the core strand,lower ratios of crack propagation zones at fractures of steel wires at various layers in the core strand,overall smaller dimensions of wear scars of steel wires in various layers,and easier discarding of steel wire rope.