Behaviour under Impact of Mixed Adhesive Joints for the Automotive Industry

M R G Silva,Lucas F M Da Silva,E A S Marques

doi:10.1590/1679-78252762

Abstract

The automotive industry is increasingly using adhesive joints bonding advanced lightweight materials to reduce vehicle weight. Strength under impact loadings is a major concern for this application and mixed adhesive joints can effectively improve the joints by combining stiffness and flexibility on the same overlap. This work introduces and studies several configurations for static and impact tests of mixed adhesive joints with four adhesives in different combinations. The main purpose of this work is the development of a strong adhesive joint using a mixed adhesive layer and perform a series of mechanical to study its mechanical behaviour. It is concluded that the use of the mixed adhesive technique improves both static and impact strength by introducing flexibility to the joint which subsequently allows more energy absorption when introduced in crash resistant structures.

Highlights

The lightweight and complex structures used in aeronautical, automotive and aerospace industries commonly employ adhesive bonding in their manufacture
All of the four adhesives in study were tested in a single adhesive application for reference purposes but only the two main configurations of mixed adhesive joints in study were tested due to the previously described problems encountered during the manufacturing and static testing stages
Comparing the maximum load of all of the configurations, it is clear that apart from the RTV106 only configuration, the joints that had the highest energy values were those containing mainly ductile adhesives or brittle ones combined with ductile adhesives in mixed adhesive layers, which is the case of the combination of DP-8005 with AV138

Summary

Introduction

The lightweight and complex structures used in aeronautical, automotive and aerospace industries commonly employ adhesive bonding in their manufacture (da Silva, 2011a). For high strain rate applications, the use of a stiff adhesive is not ideal. It can provide high static strength but the joint may be brittle and perform badly under impact. Standard epoxy adhesives used to increase stiffness have insufficient energyabsorption properties, which means reduced shear strength and peel resistance under impact. In the 1990s a new generation of toughened epoxy adhesives called crash-resistant adhesives, arrived on the market with good strength at high strain rates and large energy absorption capabilities (Adams, 2005)

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