Failure Loads for Model Adhesive Joints Subjected to Tension, Compression or Torsion

摘要

A simple theoretical analysis, based upon Griffith's fracture criterion, has been developed to predict the loads required to cause adhesive failure when model joints are subjected to different types of loading, viz. Tension, compression, and torsion. Two model joints are considered: a rigid cylinder partly embedded in and bonded to an elastic cylinder (termed 'rod joint' here), and, an elastic cylinder inserted partway into, and bonded to, a rigid tube (termed 'sleeve joint' here). Both types of joint have been constructed, using vulcanized rubber cylinders bonded to aluminum rods and sleeves. Measurements have been made of the failure loads under tension, compression and torsional loading. They were found to be in satisfactory agreement with the theoretical predictions except, in some instances, for rod joints subjected to tension or torsional loading when the failure loads were as much as three times the predicted values. This discrepancy is attributed to friction between the partially-detached rubber cylinder and the embedded rod, enhanced to a major degree by the tendency of the rubber cylinder to shrink in radius on stretching or twisting. A theoretical analysis of the effect of friction is presented. It predicts increasingly large pull-out forces or torques, as the depth of embedment increases, until frictional seizure occurs. Experimentally, frictional effects were eliminated by applying an internal gas pressure to the region being detached. All of the failure loads were then found to be in satisfactory agreement with the original theory, ignoring frictional effects.