New Fatigue Test Method for Evaluating the Performance of Adhesive Bonded Joints

As a result of environmental goals, global manufacturer's and suppliers of materials and engineering components across industries have been challenged to reduce structural weight, materials use, and manufacturing costs, while ensuring quality standards and safety requirements. In order to address these challenges, materials are often considered to optimize performance typically via multi-materials combination and adhesive bonding. However, the differences in physical, chemical, and mechanical behaviour of the individual constituent materials once joined together creates a much more complex system than is the case for monolithic materials. The majority of engineering structurally bonded components are often subject to variable or repeated stresses whilst simultaneously experiencing changeable environmental conditions. Therefore, an understanding of the effect of fatigue and environmental conditions on the performance of adhesive joints, at the design stage, are considered critical parameters for reliable joint design. Whilst it is recognized that fatigue is responsible for a significant number of failures in adhesive joints, adhesive selection is still often based upon simple quasi-static test results, determined at room temperature. This is generally a consequence of the complexity of fatigue behaviour and associated difficulty in reproducing expected service stresses and exposure conditions. Indeed, most parameters are held constant to simplify fatigue laboratory programmes. In order to overcome the limitations of traditional fatigue testing of adhesive joints, an innovative fatigue test method (FTM) was developed, based on a combination of stress and ageing conditions using the dynamic mechanical analysis (DMA) equipment. Joint specimens using two different adhesives and two surface pre-treatments were tested under traditional fatigue lap-shear tests and compared with a new FTM under dry room temperature conditions. Other specimens were also subjected to humidity effects. The outcome of the thesis delivers a new FTM, based on one specimen configuration that can be adapted as to evaluate the fatigue and environmental durability characteristics of adhesive joints under more appropriate stress conditions. The preliminary results demonstrate the test to be more sensitive to loading and environment than traditional lap joint fatigue tests.

Grantor dc:publisher

Oxford Brookes University

Year dc:date

2018

Author dc:creator

• Laranjeira, João Pedro Dos Santos

Contributors dc:contributor

• Broughton, James
• Pagliuca, Antonio

Statement dc:rights

• All rights reserved

Language dc:language

en

DOI dc:identifier

https://doi.org/10.24384/h6v8-4g16

OAI identifier oai:identifier

tle:c608b4dd-8958-4070-b875-df8c70a6c649:d6bd9758-527a-46cd-bfe2-c433766e8fca:1