Fatigue damage monitoring in carbon fiber reinforced polymers using the acousto‐ultrasonics technique

Abstract

This study focuses on the nondestructive monitoring of damage developed in carbon fiber reinforced polymers during fatigue loading via in situ acousto-ultrasonics (AU) measurements. Carbon nanotubes (CNTs) were used as modifiers of the epoxy matrix of quasi-isotropic carbon fiber reinforced laminates and consequently two composite material systems (one with matrix doped with CNTs and one with nondoped matrix) were manufactured and tested. The AU technique is utilized toward the monitoring of damage development, evolution, and accumulation during the fatigue tests. The AU waveforms acquired are processed using conventional (both in time and in frequency domain) as well as innovative wavelet-based signal processing techniques to extract parameters-indicators capable of monitoring and quantifying the damage accumulation into the test coupons. Based on the analysis of AU monitored signals, critical descriptors (parameters) were identified that show significant variation and monotonic behavior throughout the tests and thus can be proposed as potential candidate parameters for monitoring the damage development in composite materials. POLYM. COMPOS.,

Damage detection of glass fiber reinforced composites using embedded PVA–carbon nanotube (CNT) fibers

“…Pantelakis et al used ultrasonics to quantify the developed damage in APC2 composites after fatigue testing [34], [35] and correlate the findings with residual mechanical properties of the material. Loutas and Kostopoulos used acousto-ultrasonics and acoustic emission techniques to quantify damage development in carbon/carbon, woven reinforced composites [36], [37]. Philippidis et al classified acoustic emission signals from composites as to their origin in order to characterize each individual damage mechanism [38].…”

Very high cycle fatigue of fiber‐reinforced polymer composites: Uniaxial ultrasonic fatigue

“…The number of inter-fiber failures increases to a crack saturation state, where no further inter-fiber failures arise, this damage stage is called CDS. [51][52][53] The initiation of a matrix crack results in the release of stress concentration and deceleration of material property degradation until the crack density ceases to increase, marking the attainment of the CDS, which is characterized by saturated cracks. Furthermore, it is important to note that the CDS of FRP composites is solely determined by the material properties and is unrelated to external factors including the loading path.…”

Acoustic emission signal processing framework to identify fracture in aluminum alloys

“…Furthermore AE data has been coupled and cross-validated with a variety of other NDE techniques including infrared thermography [20,44], digital image correlation [5, 7-9, 12, 20, 25, 40, 45, 46] , ultrasonic testing [30,47], and visual inspection either through imaging [9,20,48,49], or microscopy [1,[50][51][52][53][54][55]. Specifically, in relation to fracture events, AE monitoring has been coupled with DIC to identify the onset of visible crack growth to identify AE signals that can be attributed to this damage mechanism.…”