Research on Mechanical Model and Fatigue Crack of Tubular Joint

Abstract

When the tubular joint is under stress, the stressed conditions on the intersection line are rather complicated. This article proposes to establish a cylindrical coordinated system for the stress on a tubular joint with axial direction, radical direction and circumferential direction as directions of coordinate axis. The system resolves the stress on points of the line of intersection along those three directions and establishes a mechanical analysis model for the stress on the tubular joint based on that. Besides, with combination of conditions of fatigue cracks of tubular joint, effective tensile stress specific to I-shape cracks are put forward and relevant mechanical formula are deduced accordingly. By taking fatigue tests of tubular joints of CaoEJiang Bridge as examples, the article also works out the position of the maximum geometrical value of stress on the line of intersection of tubular joint with applications of mechanical models and computational formula presented in the paper and compares the position with the result of test to explain the result of test.