BALANCED AND UNBALANCED PATCHING OF CRACKED LAP JOINTS USING WEIGHTEDADHESIVE PLATE ELEMENT

First order shear deformation theory is applied to analyze the behavio r of one-side (unbalanced) and two-side (balanced) patched lap joints containing initial through cracks. The joints are made of adherends bo nded together by adhesives. An adhesive interface plate element is int roduced; it consists of an adhesive layer weighted by influence of the adherend. The thin adhesive layer is assumed to behave elastically an d modelled as a simple tension-shear spring. The mathematical model co ntains layers of adherend and weighted adhesive layer. Finite elements are employed to model the adherend with an 8-node isoparametric plate element and interface layer with a 16-node plate element. Numerical r esults are obtained for one-side and two-side patches the width of whi ch could be narrower or wider than the crack length. The former leads to bulging and possible peeling while the latter provides better bondi ng. Stresses and crack-tip stress intensity factors are calculated for different patch thickness. Effectiveness of the weighted adhesive lay er model is exhibited by comparing the present results with those foun d in previous work where the adhesive is modelled as an individual lay er.