Mechanical Properties of Welded Joints at Steel Tubes with Square Cross Section

Abstract

Welded construction working properties are highly influenced by the stress and strain distribution in welded joints zones. Stress and strain distributions are determined by stress concentration provoked by geometrical discontinuities and heterogeneous of material. Stress concentration changed the stress distribution, position of maximal stresses and, by that, the position of danger cross section zone which act as damage and integrity safety risk. This paper deals with experimental determination of stress concentration influence on welded constructions integrity. The experimental procedure was done on welded joints models in static load conditions on samples made of commonly used steel tube with square cross section. Experimental procedure was conducted on existing testing devices in Welding Laboratory and Material Testing Laboratory at Faculty of Mechanical Engineering in Kragujevac. The models of welded joints at steel tubes were loaded to bending and maximal bending force was determined. Additional stress concentrator was introduced to the models, as circular hole in axis, to determine the influence of multiple stress concentration to maximal obtained bending force. The aim of this paper is to analyze influence of stress concentration to the resistance of welded structures. Stress concentration were analyzed by experimental approach objected to include as much influential factors as it is possible. The main objective of stress state distribution is creating the precise analytic model and to obtain the relevant data and information for constructions evaluating and optimizations, so as to perform integrity, safety and reliability analysis. This paper pointed out the necessity of analyzing the welded constructions on different dimension levels. Further investigations in this area have to be continued by development of numerical model of the welded construction which will, in involvement with adequate software, complete the experimentally obtained results.