Shape and size optimization for weight reduction on sheet metal, corner, and rail of the canister

Canister is one of the main subsystems of the missile system (excluding the missile), in which missile is fired. It is a cylindrical or prismatic structure that protects the missile against environmental conditions and loads that occur during storage, transportation, and firing. Due to weight constraints of the upper system (firing units), the canister structure is expected to withstand loads, and to be light in weight. Depending on the requirements, analytical approaches, experience and intuition of the designer, the canister structure is designed by using profiles such as sheet metal, pillars, rails, corners, auxiliary pillars, many sub-parts and fasteners. In this thesis, shape and size optimization studies are carried out to reduce the weight of sheet metal, corner and rail parts in the canister. On the canister, by using a thinner sheet with bead form instead of plain sheet metal, strength and similar displacement can be achieved under the pressure of the missile firing. The optimum bead form is determined and the added to sheet plate is intended to have a similar displacement to that of a flat sheet plate and to be durable (below the yield strength of the material) but lighter. In this context, under the pressure load, flat sheet and beaded sheet plates are analysed with ANSYS finite element software and von Mises stresses and displacements are calculated. Considering the design constraints and boundary conditions, the best values for the bead radius, rounding and height in the sheet are obtained by using design of experiments and response surface methods (or surrogate models). According to the optimization study of the sheet metal, it is observed that 3 mm beaded sheet metal provided 19.9% weight reduction at a similar displacement compared to 4 mm flat sheet metal plate. The corners and rails are thickened in order to give strength to the structure and to have less displacement under the weight of the canister and the weight of the missile. Therefore, the canister weight does not satisfy the desired criteria and this situation requires an optimization study. Corner and rail parts, which constitute the main strength element of the canister structure, are analyzed at the level of the canister structure with ANSYS finite element software, and stresses and displacements are calculated. While remaining below the allowable displacement values in the standby conditions of the canister, it is aimed to optimize the weight of the corner and rail parts. For this purpose, optimization studies have been completed by using design of experiments and response surface methods by considering the design constraints and boundary conditions of the corner and rail parts. According to the optimization study of the the corner and rail parts on the canister, it is observed to obtain that 51.1% weight reduction on the corner and 10.3% weight reduction on the rail compared to first design on the canister corner and rail parts. As a result of all these optimization studies carried out for the sheet metal plate, corner and rail parts of the canister, a 12.0% weight reduction was achieved at the canister structure by adhering to the constraint functions under static conditions compared to the original design.