DESIGN OPTIMIZATION OF WING STRUCTURE GRID COMPOSITE USING GENETIC ALGORITHM: CASE STUDY CIVIL TRANSPORT AIRCRAFT 19 PASSENGER CAPACITY

• Main Author: GUSTI NGURAH SUDIRA (NIM : 33612001), I
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/22504
• Institution: Institut Teknologi Bandung

Tight competition among aircraft industries in the world motivates the designer of making structure design innovation to obtain structure weight reduction. Structure weight reduction has impact of aircraft fuel consumption, range, payload, etc. Some solution can be used to reduce structure weight, namely utilisation of composite as replacement of metal, change of design type from traditional to grid structure, improvement of design and analysis method, and improvement of manufacturing technology. Currently, researcher and designer have introduced new technology of design, manufacturing, and aplication of composite material. Aplication of composite material in aircraft design, showed high progress in component content percentage. Airbus A350 and Boeing 787 are two modern airplane of using composite material to obtain structure weight benefit. <br /> <br /> <br /> According to long time experiences of using grid structure in civil building and spacecraft field, the researcher found opportunity of using grid structure in aircraft design. Grid structure have been studied by researcher to obtain the posibilities of replacement monocoque skin-stringer and honeycomb core sandwich. Most of grid structure application use cylindrical model in spacecraft field. Application of grid structure in aircraft design is a new penetration. Fuselage is opten time used as the research object of grid structure, geometrically similar shape with grid structure in spacecraft field application. <br /> <br /> <br /> Application of grid structure in wing design are creating some problem namely structure grid modeling method, design and analysis tools that can be used, and the method of design output verification. In order to obtain the optimum design, this research used optimization method of grid structure design for aircraft wing by the application of genetic algorithm (GA) and finite element method (FEM). Genetic algorithm is vary populer due to the capabilities of getting solution in the case of discret data and big numbers of design variable. Genetic algorithm is probabilistic optimization algorithm that was generated based on evolution theory. The aplication of GA on grid structure design especially for aircraft design can be classificated as a new method. Eventhough there are many algorithm, but the basic structure of GA is still the same, i.e., consist of initial population, fitness evaluation, selection, crossover, mutation, and objective function. <br /> <br /> <br /> The objective of this research is the application of grid structure on wing design of N219 aircraft model that consist of composite CFRP IM6/5208 skin and aluminium stringer grid in preliminary design phase. The other objective of this research is generating of optimization tools with FEM support for structure grid design of aircraft wing. <br /> <br /> <br /> The first activity of this research is generating optimization tools with the main activity of generating FEM code with the capabilities for analysis wing box with contains of composite skin and aluminium stringer grid. After finish of generating otimization tools including validation process, application of optimization tools for grid structure design of aircraft wing at preliminary design phase can be performed. The application of optimization tools was started from planar model, and then wing box, and finally design of wing box structure using N219 wing model. Buckling analysis process was conducted separated from strength based design optimization process, using Nastran commercial program. <br /> <br /> <br /> The conclusion can be obtained namely grid structure lighter than traditional structure. The differences of weight for the two type of structure increase with increasing of swept angle. This condition show that grid structure more effective if it was applied on high swept angle wing. Critical load and critical load factor for grid structure bigger than traditional structures. Ratio of buckling factor with respect to its weight, showed superiority of grid structure compared with traditional structure.