6926475973

The Technologica! Inst.. Northwestern Univ., Evans-ton, IL 60201. J. Acoust. Soc. Amer., 75.(3), pp 685-694 (Mar 1984) 8 figs, 10 refs

Key Word*: Membranę* (structural memberi), Sound waves, W»ve tcattering

A flextole membrano it set in an intinite piane baffle. The piane teperates an ecoustic field from a vacuum. A time harmonie wave i* incident from the fluid on the membrana. When the frequency of the incident wave it not cloee to an inwacuo retonent frequency of the membrana, the reaction of the fluid on the membrana i* tmall. However, near a reaonant frequency the fiu id-membranę coupling it signifi-cant. The method of matched asymptotic expensions i* uted to obtain an atymptotic expention of the scattered field. It i* uniformly velid in the incident frequency.

Kentron International Inc., Hampton. VA. Rept. No. NASA-CR-172215, 41 pp (Oct 1983)

N84-12528

Key Words: Platę*. Rectangular platet, Fourier trantforma-tion

The von Karman equat»n* of nonlinear elatticity are tolved for the cate of a vibrating rectangular piąte by meens of a Fourier *>ectral trantform method. The amplification of a particular Fourier modę by nonlinear transfer of energy it demonttrated for thi* con*ervative system. The multi-mode system it reduced to a minimal (two modę) system, retaining the qualitative feeturet of the multi-mode system. The effect of a modal control law on the dynamics of thit minimal nonlinear elastic system itexamined.

PLATES

(Alto tee Not. 1568. 1736.1741)

84-1716

fat-Piane Accełerationa and Forcea on Fretjucncy Oiange* in Doubły Rotated Ouartz Platea

P.C.Y. Lee and Kuang-Ming Wu Princeton Univ., Princeton. NJ 08544, J. Acoust. Soc. Amer.. 75 (4). pp 1105-1117 (Apr 1984) 17 figs. 17 ref s

Key Word*: Platet, Ouartz, Retonant frequencie*

Two-dimenslonal equationt of motion of doubly rotated ąuertz platet for the thicknett-thear. flexure, and exten-tbnal vibretiont under In-płane inłtiel ttrette* ara employed to predict changet in the fundamenta i thicknete-ahear fre-quancie* due to initiel ttre*tet. Two type* of initial ttrette* are contkJered: ttrette* due to a pełr of diametral force*. and atretee* due to ateedy eccelerationi for a threa-point "T*'-thaped mourw and a four point °>"-thaped mount configuration. Force eensfcfyfty and acceleration tensłth/rty coefficientt are computed and compered włth experłmental data and exłttłng computed retułta.

84-1717

Nonlinear Dynamie* and Contro! of a Yibrating Rectangular Platę

J.V. Shebalin

84-1718

Large Amplitudę Free Yibrationa of a Square Ratę of Yariable Thkknew

S.K. Chaudhuri

Acharya B.N. Seal College, Cooch-Behar. W. Bengal, India. J. Sound Vib.,_92. (1). pp 143-147 (Jan 8, 1984) 1 fig, 1 table. 12 refs

Key Wordt: Platet, Rectangular platet, Veriable cross section, Frae vibration, Large amplitudat

The large amplitudę free ybratient of a tquare piąte of exponentiaMy yarying thickness are inyestigated by uting von Kirman'* equatk>ns expreteed in term* of displacement componentt. The numerical reaultt are given in tabular form.

84-1719

Effects of Geometrie Imperfectiona on Yibrationa of Biaxially Compreaaed Rectangular Fiat Platę*

D. Huiand W.W. Leissa

Ohio State Univ., Columbus. OH, ASME Paper No. 83-WA/APM-20

Key Wordt: Plata*, Rectangular platet. Geometrie Imperfec-tion effect*. VK>ratk>n frequenciet

Thit peper dealt włth the effect* of geometrie imperfectiont on the yibration frequenciet of timply supported flet płata* under in-plene uni*xi*l or biaxlel comprestion. The analyti* i* based on a aołution of the nonlinear von Karman equatk>ns for flnłte deflectiont, Incorporating the influence of an inittal geometrie imperfection.