Investigation of fatigue crack propagation in adhesively bonded joints used in aluminium vehicle structures

  • Piyush Gaur

    Student thesis: Master's ThesisMaster of Science by Research


    Adhesive Bonding is an attractive alternative to conventional joining methods, such as welding and mechanical fastening. In applications such as primary aircraft structures or automobiles elements adhesive bonding competes with traditional bolting, riveting or welding. The advantages of adhesive bonding includes high strength/weight ratio, possibility to join any combination of materials, high corrosion resistance and improved fatigue performance. Although, adhesives can be used alone, most of the volume manufacturers can't afford the level of quality control required and have opted to employ hybrid joining methods containing adhesives with spot welds or self piercing rivets because they do not have a reliable software method to analyze and predict the lifetime of bonded or riveted joints. In analysing adhesively bonded joints for design purposes, important properties to consider are strength, stiffness, weight and nature of stress distributions.

    In this research, a new mathematical method based on stiffness drop of adhesively bonded joints has been investigated and presented to determine the fatigue crack propagation rates and obtain the crack growth curves for these joints. This method makes use of the raw laboratory fatigue test data and finite element based stiffness data of bonded joints. This concept has been tested and validated for T-peel and single lap shear bonded joint configurations. The bonded joint configurations were prepared using aluminium alloy AA5754 and the adhesive used was Betamate Epoxy adhesive 4601, which is high performance, heat curing, epoxy adhesive. The entire tests were conducted under constant amplitude loading using an R ratio of 0.1 and frequency of 10Hz. The damage models for this work were developed using computational fracture mechanics tools in abaqus.

    Various curve fitting models were reviewed and employed in this method to combine the stiffness data obtained from FE damage models and fatigue test data of T peel and single lap shear bonded joints to calculate the fatigue crack propagation rates. The methodology investigated in this work provides a way to obtain the fatigue crack growth curves for adhesively bonded joints by combining the finite element modeling data with fatigue test data of bonded joints.
    Date of Award2011
    Original languageEnglish
    Awarding Institution
    • Coventry University
    SponsorsJaguar Land Rover
    SupervisorPaul Briskham (Supervisor)

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