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G. M. Warner, Ph.D.
George David/United Technologies Corporation Assistant Professor
Phone: (202) 806-6607
Email: g_warner@howard.edu
Research Topics
Finite Element Analysis of the Human Knee Joint; Energy Harvesting of Rotating Structures; Fluid-Structure Interaction; Vibration and Stability in Rotating Structures; Structural Optimization
Summary of Recent Research
1. With the advance in low powered MEMS sensors, non-contact slip ring systems can be used to provide feedback from sensors in rotating machinery. But providing power to these sensors is an issue. One approach would be to harness power from the untapped surrounding energy which could be used to recharge and/or replace battery powered connections. One method to accomplish this is to use piezoelectric materials (PZT) to capture energy lost due to vibration and rotation of the test equipment. This captured energy can then be used to provide uninterrupted power to the appropriate sensors. Our research explores the available power that can be used for harvesting.
2. Meniscal tears in the knee are very common in society. Orthopaedic surgeons routinely perform surgery to remove a portion of the torn meniscus. This surgery is referred to as a meniscectomy. It has been shown that individuals who undergo meniscectomies are at increased risk for developing are knee osteoarthritis. In order to investigate the effect meniscectomies have on load bearing in the articular cartilage, an axi-symmetric finite element model of the knee joint was analyzed. The model employed considers the meniscus, articular cartilage, and portions of the femur. Eight cases have been modelled including the knee with intact meniscus in addition to 10%, 20%, 30%, 40%, 50%, 60% and 65% medial meniscectomy. Under the axial load of human weight on femoral articular cartilage with 65% of meniscectomy maximal shear stress grows up to 445% compared to knee with intact meniscus. After 40% removal of meniscus high contact stresses took place on cartilage surface.
Recent Publications
Warner, G.M. and Renshaw, A.A. (2001). “Thickness Profiles for Rotating Circular Disks That Maximize Critical Speed”. Journal of Applied Mechanics 68 (3): 505-507.
Warner, G.M. and Renshaw, A.A. (2003). “Multiple Equilibria of Hydrodynamically Coupled Flexible Disk Rotating Inside a Thin Housing”. Journal of Applied Mechanics 70 (1): 142-147.
Warner, G.M., Nayeb-Hashemi, H., Olia, M. (2005) “Flow induced vibration of an axisymmetric flow between two parallel disks”. Proceedings of the 2005 ASME Design Engineering Technical Conference, Long Beach, CA.
Amini, R., Warner, G. M., Nayeb-Hashemi, H. (2005) “Natural Frequency Analysis of Liquid Filled Tanks”. Proceedings of the 2005 ASME Design Engineering Technical Conference, Long Beach, CA.
Gupta, S., Warner, G.M. (2006) “Energy Harvesting for Rotating Structures Using Piezoelectric Generators”. Proceedings of the 2006 ASME International Mechanical Engineering Congress and Exposition, Chicago, IL.
Yang, N., Warner, G.M., Nayeb-Hashemi, H. (2006) “Ground Excitation and Resonance in Liquid Filled Tanks”. Proceedings of the 2006 ASME International Mechanical Engineering Congress and Exposition, Chicago, IL.
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