Evaluation of Fatigue Damage in Adhesive Bonding: Part 2: Single lap joint

Damage parameters for crack initiation in Single Lap Joint (SLJ) are determined by combining continuum damage mechanics, Finite Element Analysis (FEA) and fatigue experimental data. Even tough SLJ has a simple configuration; the stresses in the adhesive region are quite complex and exhibit a multi-axial state. Such a condition leads to the need to introduce a general value of triaxiality function in the damage evolution law rather than using a triaxiality function equals to unity as in the case of uniaxial stress state, e.g. bulk adhesive test specimen presented in part 1 of this paper. The effect of stress singularity due to the presence of corners at edges also contributes to the complex state of stress and the variability of triaxiality function along the adhesive layer in SLJ. The damage parameters A and β determined in Part 1 for bulk adhesive are now extended to take into account the multi-axial stress state in the adhesive layer as calculated from FEA.