Acoustic-ultrasonic nondestructive evaluation of double-braided nylon ropes using the stress wave factor

Abstract

Acoustic-ultrasonic nondestructive evaluation (NDE) has been conducted on a new dry Samson double-braided 2-in-1, 0·64 cm ( 1 4 in ) diameter nylon rope using the stress wave factor (SWF) measurement at various rope tensions. The rope samples considered were undamaged ropes and damaged ropes with core cut, core removed and cover cut. It is observed that different types of rope samples have their own SWF versus load characteristics. A SWF model based on two competing mechanisms for stress wave conduction in ropes has been developed. The two competing mechanisms are the decreasing transducer-rope contact area with increasing rope tension and the increasing rope compaction versus increasing rope tension. This competing-mechanisms model is found useful in describing the SWF characteristics for damaged and undamaged rope samples. Thus, this study indicates that the SWF can result from combined complex mechanisms and that the proper use of the SWF as an NDE technique must be accompanied by adequate SWF modeling.