Structural optimization of a composite launch tube of man portable air defense system

The weight criterion has always been of great importance for the parts produced in the defense industry. Composite materials are among the materials that are frequently preferred in the defense industry due to their advantages in terms of weight and mechanical strength. In this thesis, a weight optimization study was carried out by creating a finite element model for the composite launch tube that is being developed and used in the man portable air defense system. It is aimed to obtain a realistic solution by adding additional criteria to the weight criterion. Cost fomulation has been carried out by considering all criteria and optimum design has been achieved. In the weight optimization study, winding thicknesses and winding angle were determined as design variables. The safety factor obtained by using the Tsai-Wu damage criterion was used as the constraint function. The launch tube was modeled via finite element method and thermal and structural loads were applied on the launch tube. The suitable element size for the finite element method was determined by performing a mesh convergence study. In the next step, design of experiments were created using the latin hypercube sampling and central composite design methods. Using the specified design of experiments, different surrogate models and different optimization methods were discussed and optimization study for weight was performed. The study was carried out for glass fiber reinforced epoxy matrix material (glass/epoxy), carbon fiber reinforced epoxy matrix material (carbon/epoxy) and aramid fiber reinforced epoxy matrix material (aramid/epoxy). A comparison was made between the materials and the methods used. Using the design of experiments created with the latin hypercube sampling method for all three materials, it was observed that lighter structures were obtained compared to the central composite design method. When the response surface methods were compared, it was observed that better results were obtained with the quadratic polynomial response surface method for glass/epoxy and carbon/epoxy material, and with the Kriging method for aramid/epoxy material. When the optimization methods were compared, it was observed that the screening method for glass/epoxy material and the genetic algorithm method for carbon/epoxy and aramid/epoxy material gave better results. After the weight optimization study was carried out, availability, price and manufacturability criteria were also discussed in addition to the weight criteria. These four criteria were evaluated as percentages in order of importance and cost analysis was performed for the composite materials used. As a result, it has been observed that the carbon fiber reinforced epoxy matrix material provides the optimum cost effective design for the launch tube.