Analysis of Stress Concentration in Aerospace Aluminum Alloy Plate Welded Structure

Stress concentration of welded joint causes the partial material of welded structure to reach the strength limit prematurely under the load, resulting in failure. The influences of plate welded joint geometric parameters on toe stress concentration were studied. Through the finite element software ANSYS 2020, the first principal stress values of welded joint toe under uniform drawing load and pure bending load were calculated. The ratio of the maximum value of first principal stress to the average value of first principal stress is defined as stress concentration coefficient. The coefficient is mainly affected by the radius of the considered toe, the angle of the considered toe, the plate thickness, the widths of the upside and downside welds and the heights of the upside and downside reinforcements. For uniform drawing load, the coefficient decreases with the increase of toe radius, but increases with the increase of the other parameters. The variation range is between 0 and 98.5%. For pure bending load, the coefficient increases with the increase of toe angle, plate thickness, upside weld width and upside reinforcement height, but decreases with the increase of the other parameters. The variation range is between 0 and 105.1%. The expressions of stress concentration coefficient of welded joint under uniform drawing and pure bending external loads were obtained by regression analyses of the numerical results. The errors of the two expressions are both less than 10% within the selected value ranges that cover the geometric sizes of most plate butt joints in practical engineering.