STRESS-STRAIN STATE SIMULATION OF WELDED PLATE

ISSN 0201-744X, ISSN 0321-2211 Контроль і діагностика процесів та систем в приладобудуванні КОНТРОЛЬ І ДІАГНОСТИКА ПРОЦЕСІВ ТА СИСТЕМ В ПРИЛАДОБУДУВАННІ УДК 004.925.8:519.876.5 STRESS-STRAIN STATE SIMULATION OF WELDED PLATE Tsybulnyk S., Khotsevych M., Tovber A. National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute», Kyiv, Ukraine E-mail: Background. The most important task in choosing the shape of the structural elements of the ship’s hull is to ensure sufficient strength with a small mass. In recent years, great progress has been made in shipbuilding thanks to the use of modern welding methods for connecting parts and components. Ships hulls have become much lighter than when using riveted joints due to the transition to welding. A welded joint can provide optimum corrosion resistance, strength and economy of manufacture. However, it must be remembered that any metal, including stainless steels, may undergo certain changes during welding. Therefore, it is necessary to exercise a reasonable degree of caution during the welding process. In recent years, simulation has become a very popular method for studying processes and phenomena. In addition to mathematical methods, more and more often, authors from all over the world are starting to use simulation modeling as the main research method and compare the results with theoretical or experimental ones. There are many software products that allow you to create geometric models of objects of varying complexity. One such program is SolidWorks, which was chosen to create the geometric models in this study. Objective. Therefore, the purpose of this work is to conduct geometrical modeling (construction of threedimensional models) and simulation (study of the object by its model) of a metal plate with a weld. Also, a liquidconstruction interaction analysis will be carried out to determine the stress-strain state of the metal plate (ship’s hull element) with welds of different geometric shapes in the cross-section. Results. In this work, a three-dimensional model of the ship’s hull element with welded seams was built. To determine the vector fields of the velocity of water flow and its pressure in the ANSYS software package, a simulation of the load on the hull element was carried out using its constructed geometric model. The analysis of the obtained results made it possible to determine the stress-strain state of the ship’s hull element. Conclusions. Three forms of welds are considered, namely: V-shaped, Y-shaped and X-shaped. It is shown that at a flow rate of 5m/s the minimum load is less than at least three times for the X-shaped (double-sided) weld. The maximum loads within the hull element of the ship are almost the same. It is shown that the smallest stress within the welds (without considering the plate) arises when using an X-shaped weld. In further research it is planned to investigate the effect of loads from the water stream on the damaged weld seams. Keywords: weld seam, simulation and geometric modeling, ANSYS, SolidWorks. Introduction Each object has its own operating life, during which the reliability of the design is guaranteed. At the end of this period, the probability of destruction of the structure is high. But objects can be destroyed not only after the expiration of their lifetime. The consequences of premature destruction can be significant material costs and human lives. In order to avoid this, it is necessary to prevent the development of defects [1]. The initial stage of the destruction of the structural elements of any construction or structure is damage. The reasons for their appearance may be, for example, external natural and man-made influences, internal factors, design errors, defects and violation of operating rules. External signs of destruction are cracks. Cracks can appear due to many reasons and have different effects depending on the combination of external and internal loads. The opening of the crack 38 in the elements of the ship's construction can take place in different ways [2]. This is especially true in the conditions of operation of ships, when a crack or defect of a welded joint can lead to damage or breakage of the ship's hull. Therefore, the task of studying the hull plate of the ship is important and relevant to its operation. When working with metal plates, the welding is one of the methods of connection. Mild steel is a good welding material, and welded joints can provide optimum corrosion resistance, durability and costeffectiveness. However, it must be remembered that any metal, including stainless steel, may undergo certain changes during welding. Therefore, it is necessary to demonstrate a reasonable degree of caution during welding. This will minimize any harmful effects that may occur. It will also maintain a high degree of cor- Вісник КПІ. Серія ПРИЛАДОБУДУВАННЯ, Вип. 56(2), 2018. ISSN 0201-744X, ISSN 0321-2211 Контроль і діагностика процесів та систем в приладобудуванні rosion resistance and strength in the welding zone (which is an integral part of the base metal) [3]. In addition to steel, the use of high-strength aluminum alloys, especially for the design and construction of warships, surface ships and high-speed passenger ships, is increasing in the shipbuilding industry. Currently, various welding methods are used for the manufacture of aluminum structures of ships, namely: gas welding, laser welding and friction stir welding, but the most advantageous for the construction of aluminum structures is the friction stir welding technology [2]. If the welding mode is not followed, the structural strength decreases. Therefore, most of the scientific papers are devoted directly to the process of welding. For example, in [2] and [4], the authors reviewed the process of welding various grades of aluminum alloys using the friction stir welding. Friction welding associated with mixing the weld material is an alternative to other welding techniques for aluminum alloys. In the present studies, mechanical properties of friction stir welded aluminum alloys are examined experimentally. The insights developed from the study [2] are documented together with details of the test database. The performed tests and subject-matter literature research [4] indicate that application of FSW method to joining aluminum alloys in shipbuilding is rational. There is also a list of works devoted to the choice of methods for studying stresses in welds. For example, in [5] were investigated geometrical distortions of two steel plates jointed by metal inert gas welding. The distributions of residual stresses in this welded joint were measured by X-ray diffraction method. In article [6], the authors state that value of angular distortions in a welded T-joint depends on many parameters, including: weld geometrical dimensions, weld penetration profile, mechanical and physicalchemical properties of material, electric current source. Also, the authors indicate that (...truncated)