A Model for Predicting Joint Durability

Gledhill, R. A.; Kinloch, A. J.; Shaw, Stephen J.

doi:10.1080/00218468008078901

Cited by 102 publications

(37 citation statements)

References 9 publications

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“…The concept that a minimum, or critical, concentration of water needs to be present in order for the mechanism of environmental attack to proceed has been previously suggested (e.g. [11,12]) and obviously is in agreement with the transition currently observed between the 'Region I' and the 'Region III' behaviour, as discussed in detail below. Secondly, for the 'GBS'-pretreated joints the levels of G c are significantly higher for both 'Region I' and 'Region III' behaviour.…”

Section: The 'Gbs'-pretreated Aluminium-alloy Jointssupporting

confidence: 65%

Crack Growth of Structural Adhesive Joints in Humid Environments

Korenberg¹,

Kinloch²,

Watts

2004

The Journal of Adhesion

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The adhesive fracture energy, G c , of aluminium-alloy and steel joints, bonded with a rubbertoughened epoxy adhesive, has been measured using monotonically-loaded tests. Such tests have been conducted at different levels of relative humidity and two surface pretreatments have been employed for the substrates prior to bonding: a simple grit-blast and degrease ('GBD') pretreatment or a silane primer ('GBS') pretreatment. When G c was plotted against the crack velocity, three regions of fracture behaviour could be distinguished. At low rates of displacement the crack grew in a stable manner, visually along the interface, and relatively low crack velocities could be readily measured. This was termed 'Region I' and here the value of the adhesive fracture energy was relatively low and decreased steadily as the relative humidity was increased. On the other hand, at relatively high rates of displacement the crack grew in a stick-slip manner mainly cohesively in the adhesive layer at approximately 20 km/minute. This was termed 'Region III', and here the value of G c was relatively high and independent of the relative humidity. In this region the crack was considered to grow faster than the water molecules were able to reach the crack tip, which explains the independence of G c upon the test environment. In between 'Region I' and 'Region III', a transition region was observed which was designated as 'Region II'. The major effect of the 'GBS' pretreatment, compared to the 'GBD' pretreatment, was to increase the value of G c both in 'Regions I and III', although the presence of the silane primer had the greater effect in 'Region I'. INTRODUCTIONThe use of structural adhesives offers many advantages when compared with other more traditional joining methods such as welding, riveting and mechanical fasteners [1]. However, as with any technology, there are some potential disadvantages associated with the use of adhesives.In particular, adhesive joints may suffer environmental attack when exposed to relatively hot and humid environments. The development of a sound accelerated-ageing test method to assess the susceptibility of an adhesive 'system' (i.e. the adhesive/primer (if any)/substrate and substrate surface pretreatment in combination) to such attack would represent a significant advance, especially if such tests could be completed in a relatively short time-scale [2].The aim of a sound and meaningful accelerated ageing test must be to accelerate the mechanisms of attack seen during the service-life of the bonded joint, and not to induce misleading and irrelevant mechanisms. For example, it is well known that to accelerate the rate of environmental attack it is not possible simply to raise the temperature of the environment, since unrealistically high test temperatures will indeed change the mechanisms of attack. One method of accelerating the rate of attack which has recently been explored in detail by Kinloch and coworkers (e.g. [3]) has been the use of cyclic-fatigue tests, using a fracture-mechanics approach, conducte...

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Section: The 'Gbs'-pretreated Aluminium-alloy Jointssupporting

confidence: 65%

Crack Growth of Structural Adhesive Joints in Humid Environments

Korenberg¹,

Kinloch²,

Watts

2004

The Journal of Adhesion

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“…The mass uptake in polymer films can, for shorter times scales, be described by Eqn 1 [12]: n t kt m m = ∞ (1) For Fickian diffusion the uptake will be proportional to the square root of immersion time (n=0.5) whereas for Case II diffusion the mass uptake will be directly proportional to the immersion time (n=1). For the other non-Fickian uptake curves the coefficient n ranges between 0.5 and 1.…”

Section: Introductionmentioning

confidence: 99%

“…Diffusion coefficients derived from film uptake experiments have been used by many researchers to determine the moisture profile in bonded joints [1][2][3][4]. However, the ingress profile of moisture may be different in a free standing film than it is in a bonded joint.…”

Section: Introductionmentioning

confidence: 99%

Characterising moisture ingress in adhesively bonded joints using nuclear reaction analysis

Liljedahl

Crocombe

Gauntlett

et al. 2009

International Journal of Adhesion and Adhesives

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“…This process is governed by the rate of diffusion of water through the bulk of the adhesive and primer and is accelerated by high temperature and applied load. Loss of integrity in the interfacial region occurs due to rupture of interfacial bonds and hydration in oxide layers [14].…”

Section: Mode Of Failure Of Adhesive Joints Ultrasonic Assessment Ofmentioning

confidence: 99%