Numerical Simulation of Fabrication Processes

The progress of both computer hardware and numerical models capable of accurately representing complex phenomena has allowed the use of numerical simulations to investigate fabrication processes such as hot forging, cold stamping, welding, rolling and manufacture of advanced composites. Commercial FE packages are constantly improving and building knowledge and capabilities to perform intricate numerical simulations. However, huge challenges remain unanswered and there are great opportunities to develop state of the art research in numerical simulation of fabrication processes.

Advanced Composite Materials

The need of lightweight, good strength characteristics and resistance to thermal effects in areas such as aircraft design, robotics, automobile industry and smart control have increased interest in composite materials. The design of composite structures is complicated by the wide variety of available matrix and fiber reinforcement materials, the potential of stress concentrations, thermal residual stresses from the manufacturing process, the choice of ply thicknesses and number of plies and the spatial variation of ply orientation. Therefore, design and optimization of composite structures involve elaborate models and procedures that must be improved through further research and investigation.

Optimization

New techniques to optimize aerospace structural components shall be proposed that can handle the multiplicity of load cases typically involved in practical designs. Innovative optimization problems must be posed that lead to robust optimal designs in the sense that they are able to withstand all the possible load cases applied to the structure. The new techniques ought to be efficient from a computational point of view in order to avoid optimization problems so large that they cannot be solved by the algorithms currently available. The object of this project is to develop a design procedure that results in structures optimized against arbitrary loads. This general procedure is based on a minimax optimization strategy where the design variables are geometric parameters and/or ply orientation of composite structures while the uncertain loads are represented by parameters that describe a family of piecewise linear loadings. The loading discretization enables one to treat arbitrary boundary conditions and loads.

Smart Structures

Piezoceramics and their applications in active and shape control of isotropic and composite structures are the subject of intensive research. It has been shown that piezoceramics can be effectivelly used as actuators/sensors in the control of structures. Their lightweight, relatively low cost, small size and good frequency response make them an attractive alternative to conventional point actuators commonly used in shape control and noise suppresion. New applications of piezoelectric materials such as prebuckling enhancement, cylindrical shell actuation, and stiffening effects require the formulation of accurate models that need to be sharpened in order to predict structural responses more precisely.