Experimental determination of fracture toughness for adhesively bonded composite joints

In the present study, the experimental and finite element (FE) analyses are first carried out to investigate the deboning behavior of metal‐composite adhesive joints under modes of I and mode II loading. To conduct an FE on the debonding propagation, cohesive zone method (CZM), as well as maximum nominal stress and energy criteria, is applied. In the reliability analysis, to achieve the probability of debonding growth (PODG), limit state functions are formulated based on the energy release rate. To that end, the first‐order reliability method (FORM), the second‐order reliability method (SORM), and the Monte Carlo simulation (MCS) are used to calculate the PODG. The effect of initial debonding length on the PODG in all mentioned modes is investigated. Results obtained from reliability analysis reveal that the random variables including the initial debonding length, width, and thickness are the most sensitive variables to ascertain the PODG.

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“…Energy release rate during crack initiation is calculated based on the Irwin‐Kies equation as follow:

G_{Ic} = \frac{P^{2}}{2 b} \frac{\partial C}{\partial a} .

…”

Section: Methodsmentioning

confidence: 99%

“…As already stated in the introduction, DCB test is the most commonplace experimental tool to estimate the fracture toughness generated in mode I. The fracture toughness of mode I can be derived based on the simple beam theory, as

G_{Ic} = \frac{3 italicPδ}{2 italicba} .

…”

Section: Methodsmentioning

confidence: 99%

Reliability analysis of metal‐composite adhesive joints under debonding modes I, II, and I/II using the results of experimental and FEM analyses

Delbariani-Nejad

Malakouti

Farrokhabadi

2019

Fatigue Fract Eng Mat Struct

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“…Several studies, (e.g. Droubi et al [6,7]; Senthil et al [10]) have recognised the correspondence between the initiation of AE activity and changes in the load-displacement curves resulting from the onset of adhesive failure, during mechanical testing of various bonded specimens. Droubi et al [6] investigated the mode I and II failure of bonded metalto-metal and metal-to-composite specimens through use of AE instrumented double cantilever beam and three-point end-notch-flexure tests.…”

Section: Introductionmentioning

confidence: 99%

“…It is capable of detecting multiple damage mechanisms (e.g. adhesive failure/interfacial debonding [3,6,9], cohesive failure/adhesive cracking [9,10], adherend matrix cracking [11], fibre breakage [3,11], sandwich core failure [11]) and is not limited by a minimum detectable defect size.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Acoustic Emission Propagation in Metal-to-Metal Adhesively Bonded Joints

2018

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Acoustic emission (AE) monitoring shows promise as one of the most effective methods for condition monitoring of adhesively-bonded joints. Previous research has demonstrated its ability to detect, locate and classify adhesive joint failure, though in these studies little attention appears to have been paid to the differences in AE wave propagation through the bonded and un-bonded sections of the specimens tested, or to the effects of the wave modes excited or the propagation distances. This paper details an experimental study conducted on large aluminium sheet specimens to identify the effects of the presence of an adhesive layer on AE wave propagation. Three specimens are considered; a single aluminium sheet, two aluminium sheets placed together without adhesive, and an adhesively-bonded specimen. A pencil lead break (PLB) is used as a simulated AE source, and is applied to the three specimens at varying propagation distances and orientations. The acquired signals are processed using wavelet-transforms to explore time-frequency features, and compared with modified group-velocity curves based on the Rayleigh-Lamb equations to allow identification of wave-modes and edge-reflections. The effects of propagation distance and source orientation are investigated while comparison is made between the three specimens. It is concluded that while the wave propagation modes can be approximated as being constant throughout all three specimens, there is a significant change in the received waveforms due to the attenuation of high-frequency components exhibited by the bonded specimen. These findings may be utilised to provide a deeper understanding of acquired AE data, improving the current abilities to identify, locate and characterise damage mechanisms occurring within adhesive joints, ultimately improving safety in the use of adhesive bonding for critical applications.

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“…With the development of Adhesive bonding technology in various industrial fields [1][2][3][4][5][6][7], progressive failure behaviors of composite adhesive joints begin to gain more attention. For Adhesive bonding technology, dissimilar materials can be joined in adhesive bonds to obtain connection structures with higher toughness, lighter weight and less stress concentration than traditional mechanical connections (rivet, bolt, weld, etc).…”

Section: Introductionmentioning

confidence: 99%

Acoustic emission response and progressive failure behaviors of composite adhesively bonded joints loaded by Mode I and II

Liu

Shen

Zhang

et al. 2019

Mater. Res. Express

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The analysis of progressive failure process is one of the critical issues in the research of composite adhesive joints. In view of this point, acoustic emission (AE) is applied to real-time monitoring of the dynamic damage process of composite adhesive joints in some loading modes such as Mode I (double cantilever beam (DCB)) and Mode II (end notch flexures (ENF)). Furthermore, the high speed camera and scanning electron microscopy are carried to analyses the damage mechanisms of composite bonded joints. Results show that there are significant differences in the load-deflection curves of the specimens under the loads of Mode I and II. The main failure mode of the two types of loading modes is adhesion failure, and the accumulation of damage observed at the edge of the adhesively bonded layer cause defeat of the composite bonded joints. In addition, AE parameters including amplitude, hits, energy, and duration are connected with the fail mechanism. Furthermore, the dynamic characteristics of the AE signal, especially amplitude spectrum distribution, can provide evidences for studying progressive failure behaviors of composite adhesive joints.

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Experimental determination of fracture toughness for adhesively bonded composite joints

Cited by 16 publications

References 18 publications

Reliability analysis of metal‐composite adhesive joints under debonding modes I, II, and I/II using the results of experimental and FEM analyses

Reliability analysis of metal‐composite adhesive joints under debonding modes I, II, and I/II using the results of experimental and FEM analyses

Analysis of Acoustic Emission Propagation in Metal-to-Metal Adhesively Bonded Joints

Acoustic emission response and progressive failure behaviors of composite adhesively bonded joints loaded by Mode I and II

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