2134/35071
Yang Yu
Yang
Yu
Investigation of stresses in adhesive joints
Loughborough University
2018
untagged
Physical Sciences not elsewhere classified
2018-09-25 15:09:06
Thesis
https://repository.lboro.ac.uk/articles/thesis/Investigation_of_stresses_in_adhesive_joints/9410357
Adhesive joints are widely used as a structural element in automotive and in
aerospace applications because of their main advantage of more uniform stress
distributions within lap joints relative to conventional bonding for example riveting or
bolting. Adhesives can produce a stronger joint and potentially lengthen its service
life. However, the stress distribution in the joint is not uniform and stresses are
concentrated at the edges of the overlap. This can cause fatigue and reduce the service
life of the joint. Therefore, a large number of analytical and numerical studies have
been carried out to study this effect. Comparatively speaking, there is lack of
experimental data to prove or cast doubt on the theoretical results.
One of the main disadvantages of adhesive joints is that they have low durability when
exposed to hostile environments. Moisture is the most commonly encountered service
environment among various environmental conditions, to be considered a critical
factor to affect the service life of adhesive joints.
In this thesis, strain gauge, neutron diffraction, and X-ray diffraction methods have
been used to directly investigate residual strains and stresses and also strains and
stresses under tensile load in the adherends within adhesive joints. The residual strains
and stresses have also been studied indirectly by means of a bimaterial method. In
addition, the effect of moisture on the joints has been investigated by means of
bimaterial and bulk adhesive samples. Neutron diffraction and bimaterial experiment
results have been compared to FE predictions and good agreement achieved.
The diffraction studies show that residual stress in joints due to manufacture are small
and that water diffusion into the joint is a main critical factor affecting the
performance of adhesive and adhesive joints.