Fatigue Testing of Adhesive Joints
Abstract
This project studied adhesively bonded joints and evaluated their mechanical performance. In particular, adhesives have been modified using Thermally Expanding Microspheres (TEMs) and Expandable Graphite (EG). These additives facilitate the disbonding properties of adhesives at the end of life of components. The project also investigated the performance of applying two adhesives (low and high modulus) along the bondline to make a multi-modulus joint. The bonded joints were prepared in the lab and tested in both static and dynamic conditions, i.e. tension and fatigue, respectively. Based on the obtained results, the tensile and fatigue properties of the modified adhesives were deteriorated compared to the control adhesive (with no additives). Several factors might have affected the performance such as the additive particle size, shape, surface cleanliness and adhesive thickness. These parameters have to be optimised in order to justify the obtained results. The future recommendations for the current project suggested changing the overlap length and adhesive thickness to confirm the obtained results in the current project.
Description
The aim of the project is to study the fatigue performance of adhesively bonded joints with and without additives/modifications. To achieve this aim, the objectives are as follows:
1. Carry out a literature review related to fatigue evaluation of adhesives to define the variables affecting performance such as the overlap length, adhesive thickness, type of adhesive, percentages of additives, cycling rate for fatigue, stresses for testing (end of May 2022).
2. Select the material for the substrates, e.g. metals or composites, as well as the type of adhesive to be examined and define fatigue test parameters based on tensile testing and literature studies (end of June 2022).
3. Prepare the materials experimentally in the lab: surface preparation, joint making, curing cycles and mechanical testing, i.e. fatigue (end of July 2022).
4. Evaluate the fatigue performance of the tested joints and compare the results with literature studies for validation (end of August 2022).
Keywords
Fatigue Testing of Adhesive Joints