Еxperimental determination of stress concentration influence on welded constructions stability

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 strip profile. Experimental procedure was conducted on existing testing devices in Welding Laboratory and Material Testing Laboratory at the Faculty of Mechanical Engineering in Kragujevac. The experimental procedure enclosed the experimental determination of real material properties, so as experimental determination of strength parameters of welded samples with butt joint. Tensile strength, yield strength and elongation of welded models with butt joint and circulars holes in axle, as additional stress concentrator, was experimentally determined in order to point out the losses in mechanical properties, dominant stress concentrator and position of critical cross section. After this experimental procedure stage, tensile strength, yield strength and elongation where determined on samples with different geometrical form, strip with welded butt joint, circulars holes in axle and concave sides. This experimental procedure stage was done to establish relationship between external geometrical forms in welded joints zones and stress concentrations. The aim of this paper is to analyze influence of stress concentration to the resistance of welded structures. Stress concentration was 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 trough development of numerical model of the welded construction which will, in involvement with adequate software, complete the experimentally obtained results.