Mechanical Behaviour of Bolted Joints Under Impact Rates of Loading.

摘要

Bolted joints are extensively used in many automotive and aeronautical sectors where two members are bolted together. This particular method of fastening is vastly used in many industrial disciplines as it serves as an easy and non-destructive method to join and subsequently disassemble a complex structure. Since, bolted joints constitute an integral part of many structural components, this directly implicates the necessity to investigate the mechanical response of the bolted joints under a variety of loading rates to ensure structural integrity. Existing literature exists addressing bolted joint failure for a myriad of different geometrical configurations, and identifies the key parameters associated with it; for instance, non-dimensional ratios between width of the joint (w), edge distance (e), diameter of the hole/bolt (d) and thickness of the joint (t). However, very limited literature exists addressing the structural integrity of these joints if subjected to time- dependent loading conditions (for example, impact). The present study aims at investigating dynamic mechanical behavior of bolted joints and the role of the non-dimensional parameters affecting joint failure. The Split Hopkinson Pressure Bar technique has been employed to characterize bolted joint failure under impact rates of loading for both compression and tensile loading conditions. Hole elongation and buckling are the key modes of failure under dynamic compressive loading conditions, whereas tear-out, tension, and cleavage failure constitutes the predominant failure modes under dynamic tensile loading conditions. Aluminum-Aluminum and Aluminum-Glass fiber reinforced composite bolted joints were tested under dynamic compression and tension respectively. An experimental method was developed for measuring and monitoring the response to the bolt preload during impact. It was determined that the asymptotic region of failure shifts from static to dynamic loading conditions.