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Title
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The Optimum Use of Unconstrained Layer Damping Treatments
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Description
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Since unconstrained layer damping treatments on vibrating plates dissipate energy by undergoing bending strain, the treatment in the vicinity of lines of contra-flexure contributes little to the total damping. This report investigates the effect of concentrating the treatment in the regions of highest bending moment in order to use all the material more effectively. Three methods of analysis are presented, two of them being approximate but relatively rapid in use. The third has been used in extensive digital computer calculations to determine the effectiveness of given quantities of treatment, having given stiffness, when distributed over different proportions of the length of a vibrating, simply supported strip. The effectiveness has been assessed using certain criteria which apply to different problems, e.g. to the problems of reducing harmonic resonant vibration amplitudes, or inertia forces exerted by randomly vibrating panels, etc. Different criteria relate to each problem. It has been shown that very considerable increases of effectiveness are obtained by concentrating the treatment over a proportion of the length or area. For a given quantity and stiffness of treatment, the effectiveness may be maximised by covering certain optimum proportions. The optimum proportions corresponding to different criteria differ only slightly, permitting curves to be drawn showing the 'mean' optimum coverage required for a wide range of given quantities of treatment, and for a range of treatment stiffness. An experiment is described which confirms the validity of the theoretical approaches. The effects of temperature changes on the criteria values are also briefly considered, and it is concluded that the temperature bandwidth of the treatment when partially covering the plate is not significantly different from that when uniformly covering the plate.
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Index Abstract
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Not Available
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Photo Quality
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Not Needed
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Report Number
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ML TDR 64-51
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Report Availability
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Full text available
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Creator
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Mead, D. J.
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Pearce, T. G.
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Date
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1964
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Extent
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51
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Corporate Author
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University of Southampton
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Laboratory
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Air Force Materials Laboratory
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Identifier
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AD0607244
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AD0607244
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Contract
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AF 61(052)-504
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Access Rights
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OTS
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Distribution Classification
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1
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DoD Project
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7351 - Metallic Materials
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DoD Task
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735106 - Behavior of Metals
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Date Issued
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1964-08
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Abstract
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Since unconstrained layer damping treatments on vibrating plates dissipate energy by undergoing bending strain, the treatment in the vicinity of lines of contra-flexure contributes little to the total damping. This report investigates the effect of concentrating the treatment in the regions of highest bending moment in order to use all the material more effectively. Three methods of analysis are presented, two of them being approximate but relatively rapid in use. The third has been used in extensive digital computer calculations to determine the effectiveness of given quantities of treatment, having given stiffness, when distributed over different proportions of the length of a vibrating, simply supported strip. The effectiveness has been assessed using certain criteria which apply to different problems, e.g. to the problems of reducing harmonic resonant vibration amplitudes, or inertia forces exerted by randomly vibrating panels, etc. Different criteria relate to each problem. It has been shown that very considerable increases of effectiveness are obtained by concentrating the treatment over a proportion of the length or area. For a given quantity and stiffness of treatment, the effectiveness may be maximised by covering certain optimum proportions. The optimum proportions corresponding to different criteria differ only slightly, permitting curves to be drawn showing the 'mean' optimum coverage required for a wide range of given quantities of treatment, and for a range of treatment stiffness. An experiment is described which confirms the validity of the theoretical approaches. The effects of temperature changes on the criteria values are also briefly considered, and it is concluded that the temperature bandwidth of the treatment when partially covering the plate is not significantly different from that when uniformly covering the plate.
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Distribution Conflict
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No
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DTIC Record Exists
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Yes
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Date Modified
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Scanned by request 10/10/2019 submitted by Australian Government Department of Defence Science & Technology (Government Agency - International)
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Publisher
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Wright-Patterson Air Force Base, Ohio : Air Force Materials Laboratory, Research and Technology Division, Air Force Systems Command
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Provenance
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Lockheed Martin Missiles & Fire Control
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Type
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report
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Format
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1 online resource (ix, 51 pages) : ill.
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Subject
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Vibration
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Damping
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Optimization
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Deflection
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Moments
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Metal Plates
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Strain (Mechanics)
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Stresses
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Temperature
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Elastic Properties
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Experimental Data
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Iterations