US-Turkey Cooperative Research: Transfer of Energy from High-Frequency to Low-Frequency Modes in Structures

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Description: This award is for support of a cooperative project by Dr. Ali Nayfeh, Professor of Engineering at Virginia Polytechnic Institute and State University, Blacksburg, VA, and Dr. Gunay Anlas, Assistant Professor of Mechanical Engineering at Bogazici University in Istanbul, Turkey. The main objective of this research is to understand the effect of the lamination scheme on the behavior of laminated composite plates under dynamic loads, and the mechanism responsible for the transfer of energy from high-to-low frequency modes. Different composite systems have laminates that are laid on top of each other with different, prescribed, orientation. That difference in orientation alters the properties of the laminate. Energy exchanges in multi-degree-of-freedom systems, from high-to-low frequency modes can be the result of combinations of internal resonances and the interaction between widely-spaced modes. In this project both theoretical and experimental studies are planned. Composite plates with various thickness and lay-ups will be built and tested at VPI&SU. Theoretical studies of the systems will be carried out at Bogazici U. in Istanbul. Exchanges of visits will enable the researchers to better correlate the experimental data to the understanding of the behavior of these materials. Scope: This project will involve an established scientist, with extensive experience in both analytical and experimental mechanics at VPI&SU, with a young Turkish scientist who has demonstrated analytical capability in the same field, and who is particularly familiar with the behavior of that class of materials, namely laminated composites. The combination of facilities and graduate students at VPI&SU with the analytical skills of Dr. Anlas and the support of students and computing facilities at Bogazici University is particularly useful in accomplishing the stated objectives of this project. The American scientist is currently conducting extensive research in this area under a grant from NSF's Division of Civil and Mechanical Systems (CMS), and this international component should enhance the benefit to the US team as well as to the Turkish side. The use of composite materials is growing rapidly in many industries, including the aerospace industry and other, less exotic, industries. The results of this research should help designers select composites that will meet the required criteria for strengths and fatigue resistance. Graduate students from the US and from Turkey are expected to participate in the project. The project fits well with the objectives of the Division of International Programs.