Numerical and Experimental Modeling of Spot Welding Defects by Ultrasonic Testing on Similar Sheets and Dissimilar Sheet
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COUSTIC METHODS
Numerical and Experimental Modeling of Spot Welding Defects by Ultrasonic Testing on Similar Sheets and Dissimilar Sheets Esmaeil Mirmahdi* Mechanical Engineering, Technical and Vocational University Golpayegan, Golpayegan City, Isfahan State, Iran *e-mail: [email protected] Received February 12, 2020; revised May 13, 2020; accepted May 14, 2020
Abstract—This paper investigates the impact of defects on similar sheets and dissimilar sheets used in the automotive industry. Spot welding is one of the types of resistance welding used in this experiment for sheet welding. The thickness of sheets welded by the spot welding method can be between 0.5 and 3 mm. In this paper, the simulation is performed by finite element method for non-destructive tests on spot welding. This study investigated the propagation of ultrasonic waves in two similar layers of stainless steel and galvanized stainless steel sheets and two dissimilar layers of stainless steel sheets and galvanized stainless steel sheets in different thicknesses. This test was performed by ultrasonic immersion method and the intensity and amplitude of the reaction of the resulting defect waves and its effect on the results were also investigated. Due to the performance of finite element method softwares, Comsol Multiphysics software because of its high accuracy used. It has been studied various factors and conditions including excitation frequency, boundary conditions, the most suitable position for the probr Fto stimulate the waves, focused or unfocused waves in the simulation, sensitivity analysis of mesh size and appropriate mesh size for simulation. In this paper, the joint of similar sheets and dissimilar sheets is investigated. For this performance, the average relative error that can meet the industrial requirement is mentioned. The results of the simulation with the results of the experimental test They were compared and investigated And with the amount of error tests, have acceptable results and it can be used with the error specified and can meet the needs of the automotive industry. Keywords: spot welding, ultrasonic waves, finite element, simulation, similar sheets, dissimilar sheets, focused waves, unfocused waves DOI: 10.1134/S1061830920080069
INTRODUCTION Spot welding has been widely used to connect assemblies made of sheet metal such as in car bodies, aerospace equipment, home appliances, construction products and to a limited extent in aircraft components. Spot welding is mainly used to attach parts that are typically up to 3 mm thick. The spot weld nugget is between 3 and 12.5 mm. Undoubtedly the most used raw material used in making cars is stainless steel [1–5]. Types of spot welding defects can be: electrode hollow effect, surface melting (usually associated with electrode hollow effect), irregular welding shape, electrode deposition (usually associated with surface melting), cracks, porosity, holes and single pores [6–9]. Stainless steel sheets is very powerful and, in addition to its low price, relatively simple forma
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