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Engineering Physics Colloquium

Tuesday, October 15

11:55 AM to 11:55 AM

106 Engineering Research Building

Speaker: Professor Andrew J. Dick, Rice University
"Impact Response Characterization for Aerospace Structures"
Abstract: In certain military and industrial applications, systems and structures can be exposed to extreme impact loading conditions. These conditions can result in the impulsive loading of the structure with very high magnitude and very short duration forces. The high magnitude loading can result in significant nonlinear influence in the response and the short durations can result in an input with frequency content extending up beyond the kHz range. While methods exist to address each of these properties separately, the combination of the two conditions presents a unique and interesting problem. In this work, we have focused on the development of computational tools in two areas: force identification and nonlinear modeling. Force identification techniques have been developed in order to use local response data to determine time-series information as well as the location where the impact force was applied. Through the use of local response behavior, this method does not require a model of the complete structure but only the portion where the impacts are expected to occur. By using response data from numerical simulations and experiments, these techniques have been studied and validated. Identified force information agrees well with simulated and experimentally measured values. A new modeling method has been developed in order to correctly capture high frequency content while accurately representing the nonlinear properties, either from finite amplitude response behavior or from effectively nonlinear material properties. The high fidelity performance has been obtained through the use of spectral-domain methods employing Fourier and wavelet transforms. In this initial work, simple structures such as rods, beams, and plates have been studied. Issues identified for existing nonlinear modeling methods have been eliminated and experimental validation of these methods is ongoing.
Biography: Dr. Dick has been an assistant professor at Rice University since 2007. He received a Ph.D. in mechanical engineering from the University of Maryland, College Park. He research is focused on dynamics and vibrations of mechanical systems and structures with a focus on nonlinear phenomena. He has studied nonlinear dynamics in applications including micro-resonators, atomic force microscopes, structural vibration attenuation, and impact mechanics. He has published over 45 peer-reviewed journal and conference papers. He has organized/co-organized 9 symposia on topics related to his research. He is a member of the ASME technical committees on Dynamics and Control of Systems (Applied Mechanics Division) and Structures and Micro/Nano-Systems (Design Engineering Division).