Accession Number : AD0600170

Title :   SONIC FATIGUE DAMPING MATERIAL.

Descriptive Note : Final rept.

Corporate Author : DOUGLAS AIRCRAFT CO INC LONG BEACH CALIF

Personal Author(s) : McGowan,P. R. ; Snider,J. M.

Report Date : SEP 1963

Pagination or Media Count : 79

Abstract : Four basic material compositions were used in studies of vibration damping and adhesive stress reduction for alleviation of sonic fatigue. Variations of these four compositions were prepared by changing the ratios of the basic components and by the addition of different percentages of glass or aluminum flake pigments. Test panels simulating aircraft structures were exposed to an overall sound level of 158 decibels in a random noise generator. Best protection against sonic fatigue was obtained by adhesive damping in areas of structural attachment. Measurements of stress reduction in adhesion panels instrumented with a strain gage showed good results with materials compounded with glass or aluminum flake pigments. A polysulfide dispersion and a nylon-epoxy composition were used as the base compounds in these tests. Vibration damping tests were conducted with coated vibration strips with strain gages attached. An attempt was made to correlate dynamic physical properties of the damping compounds, such as creep and recovery, with damping efficiency. Loss moduli values were low for all materials tested but a very significant increase was obtained by the addition of flake pigments. (Author)

Descriptors :   (*SONIC FATIGUE, INHIBITION), (*VIBRATION, DAMPING), (*ADHESIVES, STRESSES), ADHESION, GLASS, ALUMINUM, PIGMENTS, SULFIDES, EPOXY RESINS, NYLON, STRAIN (MECHANICS), CREEP, COMPOSITE MATERIALS, TESTS, AIRPLANE PANELS, SIMULATION, POLYMERS

Distribution Statement : APPROVED FOR PUBLIC RELEASE