Modeling of pinning phenomenon in Iwan model for bolted joint

Abstract

Clearance between bolt and hole in the bolted joint allows the slipping of jointed beams when subjected to vibratory/shock loading. When this jointed beam slips the distance equal to the clearance of bolted joints, the pinning initiates. The pinning phenomena result in the compression and restitution phase in the bolted joint, which results in energy dissipation. This work proposes an improved Winkler elastic foundation based model referred as edge effect model to obtain the pinning force. The proposed model considers the stress concentration at edges during the pinning and is found to give satisfactory results in both conforming as well as non-conforming contact cases. Moreover, the hysteresis loop due to compression and restitution is also obtained using instantaneous contact stiffness based on pinning force obtained from the edge effect model. Finally, the proposed hysteresis loop during pinning is integrated into the Iwan model to have a better understanding of the response of the bolted joint subjected to vibratory/shock loading.