Advances in Optimal Design with Composite Materials

Abstract

It has been demonstrated that optimal design is indispensable for the sizing of complex structures using composite materials. On a significant application to the RAFALE wing optimisation saved 10% on structural weight and obtained a 25% more stiffened structure in comparaison with a classical sizing. Sensitivity analysis gives a great knowledge on the structure.

Multimodel optimisation, the most recent advance in our system, managing the synthesis of calculations on several static and dynamic models is described. A significant application to the lay-up of a composite wing panel is detailed (2 F.E. models with 3500 and 13000 DOF, 80 models for panel buckling, 480 design variables, 1000 static and aeroelastic constraints, 24 load cases).

Then it clearly appears that the passage between the rough results of optimisation to the final shape of each lay is impossible to solve with classical drawing means. An algorithm computing the optimal shape of each lay now integrated in our C.A.D. system CATIA is described. An application on the previous wing panel is detailed.

Close integration of C.A.D. systems and FEM systems, including geometry, mesh generation, analysis and optimisation is an obliged way for greater developments and applications of F.E.M.. It will enable FEM system to optimize the shape of structures. Integration of CATIA and ELFINI is described.

Multimodel optimisation on complex structures needs a nearly prohibitive CPU time on classical computers. The interest of vectorial multi-processor architectures with extended core memory is showed.