Accession Number : ADA309278

Title :   An Experimental Investigation of Nonlinear Behaviour of Beams and Plates Excited to High Levels of Dynamic Response.

Descriptive Note : Final technical rept. 1 Oct 89-31 Oct 95,

Corporate Author : WRIGHT LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Wolfe, Howard F. ; Shroyer, Cynthia A. ; Brown, Dansen L. ; Simmons, Larry W.

PDF Url : ADA309278

Report Date : 31 OCT 1995

Pagination or Media Count : 470

Abstract : Dynamic tests were conducted utilizing clamped aluminium and composite beams and plates excited by shakers and acoustic progressive wave tubes. The total strains and the components, bending and axial and the displacements were measured with increasing levels of excitation. Bistable behaviour is observed with sinusoidal excitation for both the beams and plates. The beams randomly excited exhibit a slight frequency shift and peak broadening, which can be attributed to an increased stiffening or hard spring geometric nonlinearity. The plates randomly excited exhibit a greater frequency shift and peak broadening than the beams. The implications of nonlinear behaviour of beams and plates relative to fatigue lives are studied. The Miles single mode model is modified to account for multimodal response. Trends in the strain Peak probability densities at low level and high levels of excitation are analyzed to determine the effects of axial strain on their shape. An effective multimodal cyclic frequency model is developed. A method to incorporate the effects of multimodal response of simple structures is presented with fatigue life estimates.

Descriptors :   *VIBRATION, *FATIGUE LIFE, *STRUCTURAL ANALYSIS, *DYNAMIC RESPONSE, STRESS STRAIN RELATIONS, MATHEMATICAL MODELS, STRESS ANALYSIS, ALUMINUM ALLOYS, EXCITATION, ACOUSTIC WAVES, FINITE ELEMENT ANALYSIS, STATIC LOADS, STRUCTURAL MECHANICS, BEAMS(STRUCTURAL), TENSILE STRESS, DAMAGE ASSESSMENT, DISPLACEMENT, FIBER REINFORCED COMPOSITES, STIFFENING, DAMPING, POWER SPECTRA, NONLINEAR SYSTEMS, CARBON CARBON COMPOSITES, PLATES, STRUCTURAL RESPONSE, COMPRESSIVE STRENGTH, FATIGUE TESTS(MECHANICS), SONIC FATIGUE, AXIAL LOADS, DYNAMIC TESTS, CYCLIC LOADS, BENDING STRESS, FREQUENCY SHIFT, CURVE FITTING, REINFORCED PLASTICS.

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE