Theses & Dissertations

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https://hdl.handle.net/20.500.14170/1590

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Browsing Theses & Dissertations by Subject "Adhesively bonded"
  • Publication
    Quasi-static and fatigue strenght of single lap join with dessimilar adherend under dry and hydrothermal ageing conditions
    ( 2018)
    Mariam Majid
    Significant reduction of structure weight can be achieved by introducing the lap joint combination of light alloys and composite materials compare to conventional steel material. However, these dissimilar materials undesirably cannot be joined by conventional welding method. Another related problems that reassure the research is the environmental condition effect of water absorption on the tensile strength and fatigue properties of structural joint was not investigated previously. Specifically, the effect of water immersion on hybrid joints behaviour was not observed. Therefore, in this research, the similar and dissimilar (aluminium/composite) adherends were used for fabricating single lap joint (SLJ) with different joint configuration: mechanically bolted, adhesively bonded and hybrid joint. The glass fibre reinforce epoxy (GRE) composites were manufactured through ply layers of reinforced fibre [0/90°] woven. The adhesive and mechanical fasteners of Araldite epoxy and Huck bolt were used for joining, respectively. Initially, the mechanical behaviour of joining was evaluated in experimental study at room temperature (RT) of 23 °C. A SLJ was developed for the bonding assemblies between the adherend to analyse the quasi-static strength and failure mechanism in the joints. From these experiments, the effect of different adherend combination and different joint configuration on the load transfer was analysed. Hybrid joints, on the other hand was found to exhibits the highest joint strength and stiffness as four times higher in comparison to mechanically bolted and adhesively bonded joints. The failure mechanism of adherend was characterised as mixed mode and adhesive failure on AA7075 surface. In the second stage, the strength and failure mechanism of bonding lamination subjected to cyclic loading were investigated at RT, by considering the effect of different adherend combination and different joint configuration at various stresses level. The fatigue life of hybrid joint was found to be the longest fatigue life in comparison to mechanically bolted and adhesively bonded joints at lowest and highest stress level with adherend combination of dissimilar-AA7075/GRE. The difference has been recognised as much as 80.3% and 12.5% at low stress level of 30%. Moreover, 73.3% and 33.3% were recorded at high stress level of 90%. Finally, the effect of the environment on the durability of adhesively bonded and hybrid joints was evaluated under quasi-static and fatigue strength analysis. The strength and modulus of the joint was found to decrease significantly with increase ageing time. In addition, dissimilar adherend combination of AA7075 and GRE composites in hybrid joint achieved the greatest fatigue strength with 83% and 30.2% higher than similar adherend of AA7075 and GRE composites, respectively.