Gear Diagnosis by Stress Wave Analysis

Abstract

Stress Wave Analysis (SWAN) provides real-time measurement of friction and mechanical shock in operating machinery. This high frequency acoustic sensing technology filters out background levels of vibration and audible noise, and provides a graphic representation of machine health. By measuring shock and friction events, the SWAN technique is able to detect wear and damage at the earliest stages, and track the progression of a defect throughout the failure process. This is possible because as the damage progresses, the energy content of friction and shock events increases. This ‘stress wave energy’ is then measured and tracked against normal machine operating conditions. This paper describes SWAN theory of operation, as well as case histories on several diverse types of aircraft and industrial gears. It documents SWAN’s ability to: 1) accurately detect a broad range of discrepant conditions: and 2) to characterize the severity of damage. Examples include tooth wear, tooth spalling, tooth breakage, and web cracks.