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Prediction of noise radiated from an engine. The vibration of the engine was computed by a non-linear crank-block interaction simulation process. | |
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Prediction of noise radiated from an engine. The vibration of the engine was computed by a non-linear crank-block interaction simulation process. | |
An attribute of increasing importance for a large number of products across engineering disciplines is their acoustic and vibration performance. Shipboard noise is associated with the health, safety, and fatigue of the operating personnel, and the perceived value of services by the passengers. For recreational vessels it is related with the quality of the vessel. Accoustic signatures is a major issue with naval applications since it is related to the detection of a vessel. Noise emissions are also similar in automotive, aerospace, computer disk drive, and appliances industries. Operating noise levels reflect the perceived quality of commercial products, high levels are limited by regulations, and acoustic signatures determine survivability in defense applications. Extensively published research in probabilistic underwater multipath acoustic propagation has been carried on at our department for over a decade.
Structural vibration is the main mechanism for generating noise. Technological developments in the Department of Naval Architecture and Marine Engineering at the University of Michigan are pursued in the area of vibro-acoustic simulations in low-, mid-, and high-frequency range. Research in this field is currently sponsored by NSF, ONR, NASA, DoD, Ford Motor Co., Michigan Seagrant, Bell Helicopter, and the Automtive Research Center.
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Distribution of flexural energy over a vessel at high frequency vibration computed by an energy finite element analysis. |
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Noise emissions due to the operating propellers. |
Research in sonar technology is also underway in the department to utilize high resolution, three-dimensional acoustic imaging techniques for precise underwater identification of submerged objects. This technology is based upon the high resolution scanning imaging sonar that operates at 675 kHz onboard M-ROVER, the department's state-of-the-art underwater remote-operated vehicle. Sequential sonar images are rectified in both space and time to produce an interferrometric, three-dimensional reconstruction of the target. The overall goal of this research effort is to classify and map deeply submerged objects such as historic shipwrecks to archaeological standards.
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High resolution side scan sonar image of the wreck Newell A. Eddy sunk in Lake Huron on April 20, 1893. Image acquired September 1, 1992 at a depth of 168 feet. Range lines at 10 m intervals. |
FACULTY: Beier, Lyzenga, Meadows, Perakis, Vlahopoulos