Barely visible impact damage assessment in laminated composites using acoustic emission

Abstract

Despite the key advantages of Fiber Reinforced Polymer (FRP) composites, they are susceptible to Barely Visible Impact Damage (BVID) under transverse loadings. This study investigates BVID in two quasi-isotropic carbon/ epoxy laminates under quasi-static indentation and Low-Velocity Impact (LVI) loadings using Acoustic Emission (AE). First, the evolution of interlaminar and intralaminar damages is studied by analyzing the AE signals of the indentation test using b-value and sentry function methods. Then, the specimens are subjected to the LVI loading and the induced damages are compared with the indentation test and the percentage of each damage mechanism is calculated using Wavelet Packet Transform (WPT). In consistent with the mechanical data, ultrasonic C-scan and digital camera images of the specimens, the AE results show a considerable similarity between the induced BVID under quasi-static indentation and LVI tests. Finally, the obtained results show that AE is a powerful tool to study BVID in laminated composites under quasi-static and dynamic transverse loadings.

Damage characterization of adhesively-bonded Bi-material joints using acoustic emission

“…However, according to Fig. 19, AE events with the frequency less than 150 kHz can be seen at this strain level which could be related to matrix cracking that usually has the minimum frequency compared with delamination and fiber breakage [37,38]. The strain distribution shows that the strain is minimum at the both edges of the specimen and it gradually increases when moving to the middle of the specimen where the notch is.…”

“…There are some clusters of AE signals with different frequency contents that can be related to different damage mechanisms observed in the SEM images. According to literature [12,[37][38][39], the first cluster with the lowest frequency can be devoted to matrix cracking and the cluster with the highest frequency may be related to the fiber breakage. The cluster with the medium frequency is also associated with the delamination.…”

Fracture Behavior of Permeable Asphalt Mixtures with Steel Slag under Low Temperature Based on Acoustic Emission Technique

“…Depending on the failure process of materials, the sentry function illustrates five different trends during its loading history [ 48 , 49 ]. Therefore, it is related to different damage phases of materials.…”

Monitoring the Structural Health of Glass Fibre-Reinforced Hybrid Laminates Using Novel Piezoceramic Film

“…However, most state-of-the-art methods use the wavelet packet-based energy index [ 33 , 34 , 35 ] for various applications like monitoring timber connection [ 36 ], railway axles [ 37 ] or wood utility poles [ 38 ] and for fibre-reinforced laminated composites [ 39 , 40 ]. In addition, Song et al describes a damage index representing the proportion of transmission energy losses caused by damages based on continuous wavelet transform (CWT), which has been successfully applied to bridge bent-caps as an indicator of the health state [ 32 ].…”