Computing the Growth of Naturally-Occurring Disbonds in Adhesively-Bonded Joints

Hu, Weiyan; Jones, Rhys; Kinloch, A. J.

doi:10.1016/b978-0-08-100540-8.00012-1

Cited by 3 publications

(6 citation statements)

References 13 publications

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“…where the term A ( G c ) is the apparent cyclic critical energy release rate, where G c is the adhesive fracture energy [60][61][62][63][64][65][66][67][68][69][70][71].…”

Section: Theoretical Considerationsmentioning

confidence: 99%

Requirements and Variability Affecting the Durability of Bonded Joints

et al. 2020

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This paper firstly reveals that when assessing if a bonded joint meets the certification requirements inherent in MIL-STD-1530D and the US Joint Services Standard JSSG2006 it is necessary to ensure that: (a) There is no yielding at all in the adhesive layer at 115% of design limit load (DLL), and (b) that the joint must be able to withstand design ultimate load (DUL). Secondly, it is revealed that fatigue crack growth in both nano-reinforced epoxies, and structural adhesives can be captured using the Hartman–Schijve crack growth equation, and that the scatter in crack growth in adhesives can be modelled by allowing for variability in the fatigue threshold. Thirdly, a methodology was established for estimating a valid upper-bound curve, for cohesive failure in the adhesive, which encompasses all the experimental data and provides a conservative fatigue crack growth curve. Finally, it is shown that this upper-bound curve can be used to (a) compare and characterise structural adhesives, (b) determine/assess a “no growth” design (if required), (c) assess if a disbond in an in-service aircraft will grow and (d) to design and life in-service adhesively-bonded joints in accordance with the slow-growth approach contained in the United States Air Force (USAF) certification standard MIL-STD-1530D.

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“…where the term A ( G c ) is the apparent cyclic critical energy release rate, where G c is the adhesive fracture energy [60][61][62][63][64][65][66][67][68][69][70][71].…”

Section: Theoretical Considerationsmentioning

confidence: 99%

Requirements and Variability Affecting the Durability of Bonded Joints

et al. 2020

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“…It has then been shown how the values of these parameters obtained from these ‘master’, Hartman–Schijve plots may be used (i) to compute the logarithmic d a/ d N versus logarithmic ΔG curves, which are found to be in very good agreement with the experimentally measured values, and (ii) to understand the observed cyclic-fatigue behaviour with respect to the structure of the epoxy nanocomposite polymers. Finally, the Hartman–Schijve methodology has been previously shown to be a valid approach in analysing the cyclic-fatigue behaviour of both structural adhesives [26,27,47] and polymer-matrix fibre composites [24,25,44,52]. Therefore, from the present work, this methodology will most likely be equally applicable to these classes of materials when they employ nanofillers in the epoxy polymer.…”

Section: Discussionmentioning

confidence: 82%

“…Note that the linear relationship for [22,23] encompasses all the various types of CNF and GNP epoxy nanocomposite polymers which have identical values of slope, n , and intercept, D , see tables 2 and 3. The Hartman–Schijve plots for the results [26,27,47] from two rubber-toughened epoxy microcomposites are also shown for comparative purposes. (The references are given for the sources of the original fatigue results).…”

Section: Resultsmentioning

confidence: 99%

“…The microcomposite polymers are commercially available structural adhesives, namely ‘FM73’ and ‘FM300’ which are both from Cytec, USA. Both of these epoxy microcomposite polymers are rubber-toughened structural adhesives containing a dispersed phase of spherical rubber particles of a few micrometres in diameter [26,27,47]. Furthermore, the epoxy polymeric matrices for these two structural adhesives have very different chemistries to each other, and also when compared to the epoxy nanocomposite polymers studied in the present paper.…”

Section: Resultsmentioning

confidence: 99%

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Fatigue crack growth in epoxy polymer nanocomposites

Kinloch

Jones

Michopoulos

2021

Phil. Trans. R. Soc. A.

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The present paper describes detailed analyses of experimental data for the cyclic-fatigue behaviour of epoxy nanocomposite polymers. It has been shown that the data may be interpreted using the Hartman–Schijve relationship to yield a unique, ‘master’, linear relationship for each epoxy nanocomposite polymer. By fitting the experimental data to the Hartman–Schijve relationship, two key materials parameters may be deduced: (i) the term A , which may be thought of as the fatigue equivalent to the quasi-static value of the fracture energy, G c , and (ii) the fatigue threshold value, Δ G thr , below which no significant fatigue crack growth (FCG) occurs. It has then been established that the values of these parameters, together with the slope, n , and intercept, D , of the Hartman–Schijve master relationship, may be used (i) to compute the experimental results measured for the fatigue behaviour of the epoxy nanocomposite polymers, (ii) to understand the observed fracture and fatigue behaviour of these materials with respect to the structure of the epoxy nanocomposite polymers, and (iii) to deduce the ‘upper-bound’, i.e. ‘worst-case’, FCG rate curve which may be used by industry as a material development, material selection, design and service-life prediction tool when these epoxy nanocomposite polymers are used in engineering applications such as structural adhesives and/or as matrices in fibre-reinforced composites. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

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“…Detecting and controlling adhesive bonding defects and uncertainties is challenging even with the use of the most extensive and sophisticated non-destructive methods [14][15][16][17][18]. As a result of these defects, the performance of adhesively bonded joints varies considerably.…”

Section: Challenges Of Adhesive Bondingmentioning

confidence: 99%

Defects and uncertainties of adhesively bonded composite joints

2021

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The increasing use of fibre reinforced polymer composite materials in a wide range of applications increases the use of similar and dissimilar joints. Traditional joining methods such as welding, mechanical fastening and riveting are challenging in composites due to their material properties, heterogeneous nature, and layup configuration. Adhesive bonding allows flexibility in materials selection and offers improved production efficiency from product design and manufacture to final assembly, enabling cost reduction. However, the performance of adhesively bonded composite structures cannot be fully verified by inspection and testing due to the unforeseen nature of defects and manufacturing uncertainties presented in this joining method. These uncertainties can manifest as kissing bonds, porosity and voids in the adhesive. As a result, the use of adhesively bonded joints is often constrained by conservative certification requirements, limiting the potential of composite materials in weight reduction, cost-saving, and performance. There is a need to identify these uncertainties and understand their effect when designing these adhesively bonded joints. This article aims to report and categorise these uncertainties, offering the reader a reliable and inclusive source to conduct further research, such as the development of probabilistic reliability-based design optimisation, sensitivity analysis, defect detection methods and process development.

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Computing the Growth of Naturally-Occurring Disbonds in Adhesively-Bonded Joints

Cited by 3 publications

References 13 publications

Requirements and Variability Affecting the Durability of Bonded Joints

Requirements and Variability Affecting the Durability of Bonded Joints

Fatigue crack growth in epoxy polymer nanocomposites

Defects and uncertainties of adhesively bonded composite joints

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