This research project focuses on the development of an innovative passive techniques for vibration suppression and control. A design technique of solid free-free structural optimization is formulated. In this design methodology, a structure is defined as a spatial arrangement of micro- structural elements. The structural design starts with a specified design domain as a union of every conceivable design space that can possess materials without violating any geometric and loading constraints. Then the design domain is divided into many small design cells. Each of the design cells is modeled as a `composite` material with micro- geometry perforations. By changing the parameters defining the micro-geometric structures, the topology and shape of the structure is represented effectively and desired structural dynamic characteristics can be obtained during the research project. Two major passive vibration suppression techniques are investigated:(i) eigenstructure assignment, and (ii) frequency response function shaping. The essence of the first approach is to derive the response of a structure in terms of a set of desired modal properties, whereas the second approach aims at controlling the overall response characteristics of the structure at certain critical points and through a bandwidth of interest. The proposed approaches are validated by using scaled models in experimental testing. The results of this research lead to the development of robust design techniques of passive vibration control for aerospace and automotive applications, and a new structural design tool for substantial performance improvement in lightweight engineering structures.
