The influence of the degree of mechanical heterogeneity on the strength of t-shaped welded joints

The article examines issues related to the mechanical heterogeneity of T-shaped welded joints, namely the influence of the mechanical characteristics of “solid” seams on the stress-strain state of tension-loaded joints. Mechanical heterogeneity is a characteristic to one degree or another of all welded joints. Conscious regulation of the geometric dimensions and mechanical characteristics of the “solid” seams enables the efficiency of the entire welded joint to be increased, even in the presence of lack of fusion. This process is called weld optimization. The purpose of this work was to determine the possibility and conditions for the use of mechanical heterogeneity in combination with the regulation of the geometric parameters of the seams, in order to optimize and improve the performance of T-shaped welded joints with lack of fusion at the root. The research was carried out using the finite element method based on the theory of plastic flow and the kinematic theorem of ultimate equilibrium. The work presents and considers the most characteristic stress-strain states of T-shaped welded joints with a lack of fusion in various combinations of geometric parameters with a degree of mechanical heterogeneity of the welds. Based on the data obtained, the corresponding dependences of the maximum equivalent stress and deformation for specific theoretical models on the mechanical characteristics of the joints are presented. Based on the results of research using the finite element method and previously obtained developments, a mathematical model is proposed for the design of equal-strength T-joints with “solid” seams in the presence оf a central lack of fusion. Furthermore, the boundary conditions of their application were identified and the need and prospects for further research were determined. The results of these studies can be used both in the production of building structures and in mechanical engineering.