Integrated optimal structural and vibration control design.

Structural optimization, one of the most attractive topics in engineering, has become an important element in computer-aided design. For structures with complex initial design domains, the preprocessing is required and very time consuming. To obtain smoother boundaries and more precise design of an optimal structure, many elements must be used for the purpose of modelling which increases the computing cost accordingly. To simplify the geometrical modelling and reduce the computing cost in structural design, the meshless finite element method, proposed in this thesis, is applied to solve the structural optimization problems. In the last decade, a new and exciting idea has been attracting increasing attention in many areas of engineering. The idea is that the performance of a structure can be improved by the use of active control, i.e., the controlled structural design can achieve the desired response by using less material than those without control. Accurate modelling for structures generally requires a large number of degrees of freedom for discretization in space. However, modern control theory is developed only for systems with relatively low order. How to combine structural and control theories together becomes a challenging topic for structural control engineers. The objectives of this thesis are: (1) to develop a new meshless finite element method for structural optimization problems. (2) to optimize a structure with the consideration of the control effect in steady state. (3) to design a suitable control algorithm to control the dynamic response of the obtained optimal structure. (4) to choose appropriate actuator positions for a given structural control system. From the results of proposed approach, the MFEM can really simplify the modelling for a structural optimization problem. Furthermore, if the MFEM is applied to dynamic problems, the zero energy modes can be eliminated. The response is computed for both static and controlled structural designs, and it shows the performance of controlled structural design is much better than one obtained by static design.Ph.D.Applied SciencesCivil engineeringMechanical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/129804/2/9624700.pd