Endurance calculation of welded joints in tubbing erector mechanism using digital methods

Purpose. To develop and scientifically substantiate a methodology for determining the welded joint endurance during the operation of tubbing erector mechanisms, taking into account the unique conditions of their operation, in particular, under the influence of various types of loads. Methodology. The research uses both theoretical approaches to determining the influence of loads and experimental methods. In particular, the finite element method (FEM) is used when modeling the stress-strain state in welded joints to identify stress concentration points. To assess the endurance of the joints, semi-empirical calculation methods are used, in particular, Hot Spot Stress and Effective Notch Stress, followed by a comparative analysis of the results obtained. Findings. It has been determined that the traditional recommendations for selecting parameters for calculating stresses in technical objects using the Hot Spot Stress method are not always adequate for all scenarios of loading. A modified approach to assessing the endurance of welded joints is proposed, which integrates the Hot Spot Stress and Effective Notch Stress methods and takes into account the specifics of singular stress concentrators. Based on the analysis of the assessment results, greater accuracy in predicting the endurance of welded constructions is ensured. Experimental studies have revealed that the stress values occurring in welds depend on their geometric parameters, which made it possible to specify the criteria for assessing the strength of joints using the modified Hot Spot Stress and the Effective Notch Stress methods. Originality. Since traditional methods for selecting parameters necessary for determining stresses in welded joints using the Hot Spot Stress method are not always appropriate for different types of loads, there is a need to develop a modified combination of the two methods, Hot Spot Stress and Effective Notch Stress. This makes it possible to adapt calculations to the specifics of singular stress concentrators in welded joints, which is the novelty of the research. Practical value. The research results can be used in mechanical engineering to optimize projects for creating welded constructions, increasing their endurance and reliability. The proposed calculation methods make it possible to determine more precisely the values of equivalent stresses in hot spots of welded joints and predict their endurance, taking into account the real production conditions of the equipment operation.