Assessment of the stress-strain state in the weld zone for the forklift truck frame

Abstract

In the context of an ever-increasing complication of both the construction of building machines and mechanisms and the conditions of their operation, the issues of achieving reliability and durability of the main welded joints are actualized, since the quality of the welded joint determines the operability of the assembly and the machine as a whole. In this regard, ensuring satisfactory weldability and obtaining a better welded joint are necessary conditions of increased strength for welded structures on which the working bodies of construction machinery, as well as mechanisms and their assembly units are mounted. The article addresses the key issues of improving the reliability of welded structures of building machines. Special attention is paid to the problems of strengthening hazardous areas, as well as the restoration of such zones in the welded structures of construction machinery. As an example, the article considers the frame of a forklift truck equipped with a hydraulic manipulator. Particular emphasis is placed on the fact that when calculating the distances between welds, it is necessary to take into account its dependence on the welding conditions and the parameters of the frame structures of construction machines. The stress-strain state of the frame was evaluated by modeling the state of the structure in various situations. Using finite element analysis programs, it was found that it is possible to reduce local stresses that exceed the tensile strength of the material and cause the risk of microcracks due to the welding of overlays with short seams in a checkerboard pattern, as well as finding the optimal parameters of the welds taking into account the stress concentration. It was also established during the study that the greatest influence on the value by stress concentration factors is exerted by the radius of the transition from the base metal to the weld metal. An increase in the transition radius from 0.1 mm to 1.0 mm makes it possible to reduce the value of the stress concentration coefficient.