FATIGUE DEGRADATION SENSING WITH SURFACE MOUNTED CONJUGATE-STRESS (CS) SENSOR

Abstract

This study advances a unique dual-stiffness mechanical sensor concept in the literature (termed Conjugate-stress sensor), to evaluate and validate the effectiveness of surface-mounted versions of the Conjugate Stress (CS) sensor in detecting cyclic fatigue progression under both quasi-static axial cycling and dynamic flexural loading conditions. The CS sensor’s capability to recognize fatigue was examined by observing the correlation between its readings and the host material's stiffness. Low carbon steel dog bone coupons and welded cruciform specimens were subjected to quasi-static cyclic fatigue testing. Additionally, dynamic flexural tests were performed on low carbon steel cantilever beams and welded cruciform specimens, which underwent random vibration fatigue testing. The results demonstrated that CS sensors consistently track fatigue damage, offering a promising potential for in-situ structural health monitoring and for providing continuous, real-time estimations of the remaining useful life (RUL) of materials