Adhesive bonding between dissimilar materials

Abstract

This master thesis is done at a Defense & Security Company in cooperation with the department of Industrial and Materials Science at Chalmers University of Technology. This thesis is an evaluation of adhesive bonds between composite to composite, and composite to metal in different environments. The different environments are simulated only by temperature variations to represent environmental conditions of land, sea and air. The evaluation is done through a literature study and experimental mechanical testing. The literature study resulted in a theoretical background that comprises knowledge about composites, adhesive joints and surface treatments prior to adhesive bonding. The experimental part of the evaluation is done to determine the tensile shear strength of a single-lap bond, with a test method similar to ISO4578. The material combinations tested are mostly based on usability for the Defense & Security Company, resulting in tests of glass fiber reinforced polymer (GFRP) adhered to GFRP, GFRP adhered to aluminium and aramid fiber reinforced polymer (AFRP) adhered to aluminium. All test series were bonded with the adhesive film, FM 300-2M. All combinations were tested in room temperature and at elevated temperature. GFRP to aluminium and AFRP to aluminium were tested after pre-conditioning by temperature cycling. Sandblasting was used as surface treatment for all the test samples. Production of the test samples and the adhesion process were done externally at Elitkomposit AB and the tensile shear testing was conducted at the Defense & Security Company. When bonding GFRP to GFRP the results showed that mechanical joints could be replaced with single-lap adhesive bonds. However, the results from the dissimilar test series were promising as the shear strength was high, but the it varied within each test series. Therefore, the mechanical joints can not be replaced based on these results. Further evaluation and testing are recommended in order to replace mechanical joints with adhesive bonds when dissimilar material are used.