Effect of Loading Rate and Geometry Variation on the Dynamic Shear Strength of Adhesive Lap Joints

Abstract

Dynamic and quasi-static experiments were performed using a novel lap joint specimen to evaluate the shear strength of adhesive bonded lap joints at different loading rates, length to width ratios and lap areas. Dynamic shear strength was determined by subjecting the lap joints to stress wave loading in a Split Hopkinson Pressure Bar (SHPB) apparatus. All joints were bonded by a general-purpose epoxy adhesive (Armstrong A-12®). The shear strength of the joint was determined using maximum transmitted load through the joint, assuming that the load was predominantly transferred through shear.A series of tensile and compressive experiments were performed to determine the shear strength of a lap joint, for loading rates varying from quasi-static to 2500 N/μsec The results indicated that as the loading rates are increased to 1000 N/μsec the shear strength of the particular adhesive bonded lap joint increases to three times its static value, after which it stabilizes. The effect of bonded length to width ratio on the shear strength of similar lap joints was also experimentally investigated for both quasi-static and dynamic loading conditions. Experimental results showed that maximum dynamic shear strength is achieved for a length to width ratio of 0.8. Experiments based on a 3×3 factorial design indicated a statistically significant effect of bonded length to width ratio on the dynamic shear strength of lap joints. A disordinal interaction was observed for bonded length to width ratio and bonded area, implying that the main effects of length to width ratio and bonded area on the dynamic shear strength of joints are not separable.KeywordsShear StrengthWidth RatioAdhesive JointStatic Shear StrengthSignificant Simple EffectThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.