Fatigue properties of vibration-welded nylon 6 and nylon 66 reinforced with glass fibres

The fatigue properties of vibration-welded butt joints of nylon 6 and 66 with 30 wt% glass fibres made under low and high weld pressures were examined. Fatigue testing was conducted at a stress ratio of R = 0.1 in load control at frequencies ranging from 3 to 10 Hz. Specimens tested at both high and low stress levels failed at the weld with no thermal damage. It was found that although weld pressure affected the fatigue strength, the welded specimens all had similar fatigue behaviour. The reinforced nylon 6 welded in low pressure had slightly longer fatigue life than the others.