Durability studies for aerospace applications using peel and wedge tests

Sargent, J. P.

doi:10.1016/j.ijadhadh.2004.07.005

Cited by 102 publications

(33 citation statements)

References 18 publications

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“…The adhesive bonding of aluminum structures is widely practiced in aircraft, automotive and marine industries due to many advantages over mechanical fastening or conventional methods such as welding, which include reduced corrosion and stress concentration, aesthetics and cost effectiveness [1], [2], [3], [4] and [5]. Adhesive bonding offers capabilities such as large area bonding, bonding of dissimilar materials of varying thicknesses, prevention of galvanic corrosion while bonding dissimilar metals due to the insulating properties of adhesives, lighter weight than when joined with mechanical fasteners, and the use of less or no heat to create an adhesive joint eliminating any thermal distortion or residual stresses generally caused by heating [4].…”

Section: Introductionmentioning

confidence: 99%

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications

Noormohammed

Sarkar

Paynter

et al. 2012

Applied Surface Science

146

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Structural adhesive bonding of aluminum is widely used in aircraft and automotive industries. It has been widely noted that surface preparation of aluminum surfaces prior to adhesive bonding plays a significant role in improving the strength of the adhesive bond. Surface cleanliness, surface roughness, surface wettability and surface chemistry are controlled primarily by proper surface treatment methods. In this study, we have employed a very simple technique influencing all these criteria by simply immersing aluminum substrates in a very dilute solution of sodium hydroxide (NaOH) and we have studied the effect of varying the treatment period on the adhesive bonding characteristics. A bi-component epoxy adhesive was used to join the treated surfaces and the bond strengths were evaluated via single lap shear (SLS) tests in pristine as well as degraded conditions. Surface morphology, chemistry, crystalline nature and wettability of the NaOH treated surfaces were characterized using various surface analytical tools such as scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDX), optical profilometry, infrared reflection absorption spectroscopy, Xray photoelectron spectroscopy, X-ray diffraction and contact angle goniometry.Excellent adhesion characteristics with complete cohesive failure of the adhesive were encountered on the NaOH treated surfaces that are comparable to the benchmark treatments such as anodization, which involve use of strong acids and multiple steps of treatment procedures. The NaOH treatment reported in this work is a very simple method with the use of a very dilute solution with simple ultrasonication being sufficient to produce durable joints. Graphical AbstractHighlights A very simple surface treatment method to achieve excellent and durable aluminum adhesive bonding. Our method involves simple immersion of aluminum in very dilute NaOH solution at room temperature with no involvement of strong acids or multiple procedures. Surface analysis via various surface characterization techniques showed morphological and chemical modifications favorable for obtaining highly durable bond strengths on the treated surface. Safe, economical, reproducible and simple method, easily applicable in industries.

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Section: Introductionmentioning

confidence: 99%

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications

Noormohammed

Sarkar

Paynter

et al. 2012

Applied Surface Science

146

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“…Energy released rate decreases as a −4 , where a is crack length, making stable crack propagation possible. The crack propagation is often observed directly using optical microscopy (Aglan and Abdo 1996;Sargent 2005;Adams et al 2009), generally leading to discontinuous measurements. The principal, quantitative datum is crack position from which energy release rate is calculated.…”

Section: Introductionmentioning

confidence: 99%

An in situ technique for the assessment of adhesive properties of a joint under load

2011

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Slow crack propagation in adhesive bonded joints has been characterised using an asymmetric wedge test. Crack position was evaluated from strain gauge measurements, both in the debonded part of the joint and in the bonded zone. Test temperature was changed during loading, giving insight into bond evolution. The technique allows accurate, and virtually continuous, determination of crack position to be made, and therefore the evaluation of crack speed versus fracture energy curves, as well as elastic properties of the adhesive layer. This technique also enables the monitoring of crack propagation in controlled environmental conditions to be performed, without interruption of exposure for measurements. By using a Winkler elastic foundation model to analyse results, the method seems to be the first to describe a process zone, or region where the adhesive is significantly strained under load, and a finite length specimen effect, manifested by crack front acceleration during the final stage of the test. The method was found to offer great potential to study in situ fracture and bulk adhesive properties.

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“…[26] This method is commonly used in literature for adhesive screening, effect of surface pre-treatment, [27,28] bond durability, etc. [29][30][31] It has been found that the peel strength, measured while testing, gives an indication of the adhesion strength but it also includes the work of the plastic deformation of the thin adherend. Therefore, the mechanical characteristics of the thin adherends have a significant effect on the measured peel load.…”

Section: Introductionmentioning

confidence: 99%

The use of acoustic emission and composite peel tests to detect weak adhesion in composite structures

Freitas

Zarouchas

Poulis

2018

The Journal of Adhesion

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Adhesive bonding is one of the most promising joining technologies for composite aircraft. However, to comply with current aircraft certification rules, current safety-critical bonded joints, in which at least one of the interfaces requires additional surface preparation, are always used in combination with redundant mechanical fasteners, such as rivets and bolts. This lack of trust in bonded structures is mostly linked to the fear of lack of adhesion or a "weak bond".The aim of this paper is to tackle this challenge by assessing the ability to use composite peel tests and acoustic emission (AE) technique to assess adhesion quality and distinguish a good bond quality from a "weak bond".Composite Bell Peel (CBP) tests and Double-CantileverBeam (DCB) tests were performed on contaminated and noncontaminated CFRP bonded specimens. The results show that peel strength drops significantly at the location of the contaminated interface that has led to weak adhesion, as a result from adhesive failure. The AE signals obtained during DCB tests show different features for cracks growing at the interface ("weak bonds") and inside the adhesive layer (cohesive failure). In addition to this, scattering of the AE signals were observed in the contaminated specimens with "weak bonds". ARTICLE HISTORY

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Durability studies for aerospace applications using peel and wedge tests

Cited by 102 publications

References 18 publications

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications

An in situ technique for the assessment of adhesive properties of a joint under load

The use of acoustic emission and composite peel tests to detect weak adhesion in composite structures

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