STP1256

    Constraint Effect on Fracture Behaviour of Adhesive Joints with Different Bond Thickness

    Published: Jan 1995


      Format Pages Price  
    PDF (328K) 16 $25   ADD TO CART
    Complete Source PDF (17M) 16 $109   ADD TO CART


    Abstract

    The main aims of this work are to investigate the constraint effect of adherends on the fracture behaviour of adhesive joints and to study the fracture properties of aluminium-adhesive joints using a rubber-modified epoxy resin (GIc = 2.76 kJ/m2) as an adhesive material. Compact tension (CT) adhesive joints were manufactured for a wide range of bond thickness and fracture tests were conducted. The fracture energy was found to increase, though not monotonically, towards the fracture energy of the bulk adhesive as the bond thickness was increased. The constraint and stress triaxiality at the crack tip in the adhesive joints were also characterised for various bond thickness using elastic-plastic finite element method. It was found that as the adhesive bond thickness was increased, the stress triaxiality near the crack tip was relieved by the intensive deformation of the adhesive. Furthermore, the relationship between J-integral and crack-tip opening displacement (CTOD) was dependent on the constraint around the crack tip. Scanning electron microscopy (SEM) was used to examine the fracture surface morphology. Brittle fracture mechanisms were observed for thin bonds (0.04 < t < 0.5 mm) but tough fracture mechanisms were identified for thick bonds (t > 1 mm). The fracture energy of adhesive joints was proportional to the size of the crack tip plastic zone and the transfer of the bulk adhesive fracture toughness was governed by the constraint at the crack tip. Results from this work would improve integrity assessment of engineering adhesive joints.

    Keywords:

    fracture energy, constraint, adhesive joints, bond thickness, finite element analysis, J-Q theory, crack-tip opening displacement


    Author Information:

    Daghyani, HR
    Graduate Student, Lecturer and Professor, The University of Sydney, Sydney, NSW

    Ye, L
    Graduate Student, Lecturer and Professor, The University of Sydney, Sydney, NSW

    Mai, Y-W
    Graduate Student, Lecturer and Professor, The University of Sydney, Sydney, NSW


    Paper ID: STP16405S

    Committee/Subcommittee: E08.04

    DOI: 10.1520/STP16405S


    CrossRef ASTM International is a member of CrossRef.