Impact stress analysis for the welding joint in a rotary dryer

This paper discusses the failure phenomenon of the welding joint for the flight bars in a rotary dryer under impact loading. The flight bars are utilized to provide a curtain of particles and to avoid direct cohesion of the production to the steam tubes. In addition, some gravitational hammers knock off the shell outer skin to fall off the product buildup from the shell inner surface. The condition monitoring has revealed that periodic impacts of hammers on the outer skin will result in welding joint failure between the flight bars and the shell followed by a complete detachment. Assuming that the hammer impacts the shell by a constant rotational speed, the finite element software is employed to simulate the mentioned problem. The results indicate severe stress concentration and plastic deformation around the roots of welding joints. To prevent joint failure, different mechanisms are proposed such as: relocation of the welding joints, employment of the stiffening angles and an increase in the thickness of the absorbing pad. The outcome of current study showed that relocation of welding joint toward the flight bar end and the application of stiffening angle can decrease the maximum vonMises stress by a factor of 18% and 43%, respectively. Moreover, using a composite absorbing pad will decrease the vonMises stress level up to 80% around the roots of welding joint.