A novel approach for classification of failure modes in single lap joints using acoustic emission data

Abstract

New innovative basalt fiber/epoxy composite materials are used in engineering applications such as aerospace, automotive, and civil structures due to the potential low cost of this material together with its mechanical characteristics and its failure mechanisms. Acoustic emission is a passive nondestructive testing technique for real-time monitoring of damage developed in materials and structures, which have been used successfully for the identification of damage mechanisms in composite joints under tensile loading. The present study is focussed on acoustic emission characterization of failure modes in three prominent joining methods namely, bonded, riveted, and hybrid joints during tensile test. Parametric analysis is performed on the acoustic emission data obtained during the tensile testing of these types of joints to discriminate the failure modes. Fast Fourier transform analysis using acoustic emission waveform analysis is carried out to analyze the different failure events and associate them with their dominant frequency ranges. The predominance of failure modes in each signal is used as a key in the study to discriminate failure modes on single-lap joints in basalt/epoxy composite laminate, and the results are validated with fast Fourier Transform analysis.

Acoustic emission characterization of failure modes of single-lap joints in glass/epoxy specimens

“…Adhesive failure occurs at a displacement of 0.5 mm, and also large AE count rate are observed as represented in Zone I. 24 The major difference between load versus displacement graph of bonded joints and hybrid joints is small amount of adhesive bonding still existed around the rivet. Because, all the adhesive area of the hybrid joints were not failed in the overlap region and fiber failed gradually between the displacement of 1.25 mm and 1.5 mm.…”

“…The tensile tests were conducted at a crosshead speed of 0.15 mm/min for bonded and riveted joints, and crosshead speed is 0.1 mm/min for hybrid joints. 24 The test machine data (load, displacement, and other values) of bonded, riveted, and hybrid single-lap joints were recorded by SAMOS E3.10 data-acquisition system of Physical Acoustics Corporation (PAC) and AE win software with a 3 MHz sampling frequency. was used for this study.…”

“…From Figure 17, in the time interval between 300 and 700 s, cumulative counts increased steeply in the frequency range of 110-150 kHz related to shear failure of the fastener. 24 The specimens were carefully and closely observed to understand the failure mode on singlelap riveted joints (shear failure of fastener) during tensile test. The cumulative counts of single-lap riveted joint are lower than experiencing extensive composite damage under tensile loading.…”

“…Matrix failures occur mainly in the frequency range of 80-110 kHz with low amplitude and light-fiber tear failures (failure is very close to the adhesive-substrate interface) are mainly in the range of 110-200 kHz with moderate amplitude and duration. 23,24 From the literature review, it is understood that many researchers have studied the mechanical strength and damage mechanisms of glass/epoxy laminate during the tensile test along with AE monitoring, but there is a lack of research on failure modes of single-lap joints (namely, bonded, riveted, hybrid joints) in glass/ epoxy laminate using AE technique. The main objective of this study is to investigate the lap joint strength and frequency ranges for each failure mode on single-lap joints of glass fiber/epoxy specimens under tensile loading.…”

Acoustic Emission Feasibility Study for Carbon Epoxy Coated Aluminum Corrosion Monitoring

“…Different corrosion phenomena, like intergranular corrosion [25], uniform [26,27], localized or pitting corrosion [21], have been successfully correlated with specific AE indices. A specific, for the aviation sector, advantage of AE as a corrosion monitoring technique, is that AE can also provide information on the structural integrity of FRPs which gradually are replacing traditional metallic alloys [28,29]. Thus, AE is emerging as a "multi-purpose"-on line monitoring tool leading to reduced costs of inspection.…”