Effect of Temperature on the Strength Properties of Adhesively Single-Lap Bonded Joint for Composite Laminates

摘要

The use of adhesive bonding is valued in structural design in which the single-lap joint has been widely used in the manufacture of aerospace and automotive structures. It has been anticipated that improper or inadequate surface treatment is the most known cause of failure in adhesive bonding. Hence, the objective of this research was to study the effect of surface preparation with different surface roughness by using different number of grit (#220, #400 and #600) of sandpapers on the joint strength of adhesive bonding for glass fiber composites. In addition, effect of various temperatures for different surface roughness on the joint strength has also been investigated through tensile tests under different temperatures. The relationship between joint strength with its surface roughness and temperatures effect was observed. It was found that as the mesh number of grit increased, surface roughness decreased, leading to the increase in joint strength due to better mechanical resistance or interlocking of joints. At temperature below T_g, the adhesive became brittle, leading to a reduction in strength. But, as the testing performed at higher temperature (70°C), the highest strength of bonding was obtained. At 130°C, the adhesive softened and was unable to sustain the load which led to the decrease in joint strength. Finally, the failure mode on the bonded region was analyzed and categorized as adhesive failure, cohesive failure, and mixed failure.