The design of joints for the assembly of separated structural parts has become an important research field because the efficiency of structures with joints is established, with very few exceptions, not by its basic structure but by its joints.
There are two main types of joints: mechanical and adhesively-bonded joints. The adhesively bonded joint can distribute load over a larger area than the mechanical joint, requires no holes, adds very little weight to the structure and has superior fatigue resistance. However, the adhesively bonded joint requires careful surface treatment of adherends, is difficult to disassemble for inspection and repair and degraded by hygrothermal environments.
When the adhesively bonded joints are exposed to high environmental temperatures, the tensile load capability of the adhesively bonded joint decreases because the elastic modulus and failure strength of the rubber toughened structural epoxy adhesive decrease.
The adhesive mixed with fillers may increase the strength and modulus in high environmental temperatures. However, the increase of mechanical property of the adhesive does not usually mean the increase of the tensile load capability of the adhesively bonded joint directly.
In this thesis, the properties of adhesive as well as the tensile load capability of the adhesively bonded joint with respect to the volume fraction of filler and the temperature were investigated experimentally and theoretically. Two types of fillers such as A1203 (alumina) and E glass were used. Using the dog bone type tensile specimens, the elastic modulus and the failure strength of the adhesive were obtained. As the test temperature and the volume fraction of filler increased, the elastic modulus and the failure strength of the adhesive decreased gradually. From the experiment of the adhesively bonded joint, it was found that the tensile load capability of the adhesively bonded joint decreased as the test temperature increased, but it did not always increased as the volume fraction of filler increased.
In order to predict the tensile load capability of the adhesively bonded joint with respect to the test temperature and the volume fraction of alumina, the finite element analysis was performed using the nonlinear mechanical property of the adhesive which was approximated by an multilinear stress-strain relation obtained from the tensile test of the adhesive.
The tensile load capability estimated by the analysis yielded reasonable result compared to that from the experiment.