Development of an improved adhesive test method for composite assembly design

Abstract

This study is concerned with improving performance of composite structures through the use of adhesive bonding, particularly for marine and underwater applications. Some preliminary results from tests on simple composite/composite assemblies are given first. Difficulty in modelling the failure of even these simple joints highlighted the need for more reliable constituent input data. The first objective was to define an experimental methodology enabling the adhesives of interest to be characterised up to failure. A metal-metal assembly was considered, in order to concentrate on the analysis of the behaviour of thin adhesive films. The aims were to characterise the adhesive, analyse its non-linear behaviour, and study the influence of parameters such as film thickness and manufacturing conditions. In order to be able to study the behaviour of the adhesive as a function of the normal stress component, an important parameter, a modified Arcan fixture has been developed, which enables compression or tension to be combined with shear loads. First results from this fixture are presented, together with analysis of sources of scatter in results.

The Flexible Initiation Test (FIT): A new experimental test to characterize fracture initiation in mode I at the free edge of bonded assemblies

“…These specific geometries are very difficult to reproduce in complex industrial structure assemblies, in particular on fused silicate substrate for direct bonding. Furthermore, the experimental results obtained for the epoxy resin Araldite ® 420 [12], for example, Cognard et al [13] in their results still display residual scattering.…”

Determination of the 3D failure envelope of a composite based on a modified Arcan test device

“…The main drawback of this approach lies on the manufacturing of the specimen machined from high thickness composite plates that could lead to a high scattering of the results [15]. To overcome this difficulty, Cognard and co-workers [16] have developed a modified Arcan test device. It is based on the use of specimen manufactured from thin composite plates bonded to metallic substrates.…”

Quasi‐Static Constitutive and Strength Tests

“…The compact V-notched plate (Arcan) specimen is often referred to as a ''butterfly'' specimen because of its shape. Various adaptations of the Arcan test fixture that enable samples to be tested under stress conditions having different combinations of tension and shear loading have been introduced [29][30][31].…”