The effect of fillet radius and length of the thick-walled cylinder on Von Mises stress and safety factor for rocket motor case

Abstract

The rocket motor is a crucial part of a rocket containing propellant fuel as propulsion. The rocket motor works using the pressure vessel principle because it stores liquid, solid, or hybrid propellant fuels. The most crucial factor in the rocket motor performance is the stress received on the rocket motor case during operation due to high pressure on the combustion chamber. Several factors that influence the maximum von Mises stress on thick-walled cylinders include the fillet radius and the cylinder's length. This paper investigates the effect of fillet radius and length of the thick-walled cylinder on von Mises stress and safety factor for rocket motor case. The outer diameter of the cylinder, cap thickness, and wall thickness is 122, 20, and 8 mm, respectively. The fillet radius varies 2, 4, 6, 8, and 10 mm, while the length of the cylinder is varied 300 and 500 mm. The cylinders use Aluminium 6061 material and are subject to a constant internal pressure of 10 MPa. The von Mises stress analysis is done using the numerical method with Ansys Workbench 2019 R3 software. The simulation results show that as the fillet radius increases, the Von Mises stress decreases. The increase in the cylinder's length resulted in the maximum von Mises stress increases for 2, 4, and 6 mm fillet radius variation. While the increase in the length of the cylinder resulted in the maximum von Mises stress decreases for 8 mm and 10 mm fillet radius variation. Material has a safety factor higher than 2.0 for all variations in cylinder length when the fillet radius is 4, 6, 8, and 10 mm.