Novel Simulation Techniques for Vibro-acoustic Analysis of Lightweight Structures

In search for novel materials which combine lightweight characteristics with good acoustical behavior, resonant meta-materials come to attention. Meta-materials are defined as the general family of materials engineered to have specific properties, uncommon in nature, for dedicated applications. The objective of this research is to design a periodic meta-material which can improve sound insulation behavior by introducing stop bands in certain frequency ranges. Stop bands are defined as zones in the frequency range in which no free wave propagation can occur. It is suggested that such behavior can be achieved using local systems of mass and resonators (local resonant). As a first step in the design process, one needs to have a numerical model of the proposed structure to be able to study the vibro-acoustic behavior of it. This numerical simulation can often be demanding both in time and effort, but since periodicity is assumed in our meta-material design, Bloch-Floquet theorem can be used to decrease the computational time required to analyze the stop band behavior. Using Bloch-Floquet theorem, the stop band behavior of an infinite periodic structure can be captured by the analysis of a single unit cell. A unit cell is defined as a small partition of a periodic structure which consists of, at least, one period of the repetitive geometry and contains all essential information. In addition, a new approach is adopted to provide a more flexible numerical tool to deal with frequency dependent material properties which are of more importance in lightweight damped structures.