Study on the Effect of Strain Rate of Adhesive Material on the Stress State in Adhesive Joints

Abstract

The effect of the strain rate sensitivity on the behavior of bulk materials of epoxy resin adhesives is examined experimentally using an INSTRON®-type material testing machine. In the present study, the strain rate is chosen in the range 10−4∼10−1/s. The effects of the strain rate sensitivity of adhesive joints in which solid cylinders and hollow cylinders are bonded (tubular lap adhesive joints) are also examined using an INSTRON-type material testing machine and a split Hopkinson pressure bar apparatus (SHPB). In addition, the stress distributions at the adhesive interface in the tubular lap adhesive joints under static and impact loadings are examined using two-dimentional axi-symmetrical finite element stress analysis. The results of compressive and tensile tests for the adhesive bulk specimens show that the yield stress increases as the strain rate increases. The results of quasi-static and impact shear tests for the tubular lap adhesive joints show that the shear strength increases as the strain rate increases. The numerical results show that the maximum value of the shear stress, τrz, decreases as the adhesive thickness decreases under static loadings, while the maximum value of the shear stress, τrz, decreases as the adhesive thickness is about 0.2 mm under impact loadings. These results under impact loadings show different characteristics from results under static loadings. A fairly good agreement is found between the numerical and the experimental results.