Design considerations for joining of tubular members subjected to impact loading

Abstract

This study explores the effect of impact loading in structural bar and tube welded and threaded joints. Specifically, this work concentrates on stress wave propagation and mechanical impedance to show the effect of geometric parameters on stress distribution and history inside these joined members. In this experimental work, welded and threaded bar-and-tube networks are compared with equivalent length single bars to provide a measure of joint quality. Application to dynamic experimental equipment, known as Hopkinson Bars, is considered herein due to the stringent need for wave uniformity within these systems. Explicit finite element analysis on the experimental setup was performed to provide internal stress history information to provide more insight into the causes of stress risers and spurious load reflections. A key finding in this study shows that joint impact performance reduces when joint size is either too small or too large. This optimized joint size is found to depend on the joint'seffective mechanical impedance. This study serves as a new look at potential joining considerations under impact loading.