6926475989

84-1787

Parametric Excitation in the Self-Excited Yibration System with Dry Friction (lst Report, Parametric Resonance)

S. Yano

Fukui Univ., 3-9-1, Bunkyo, Fukui, Japan, Buli. JSME. 21 (224), pp 255-262 (Feb 1984) 15 figs. 3 refs

Key Word*: Rwemetrlc excłtetk>n, Co ulomb friction, Parametric resonance

An •pplication ot Solutions of lineer Mathieu equatfc>n by • naw mathod giva* epprox)m*te Solutions in a perametrically axcitad *alf-axcłtatk>n system with dry friction. Steady solu-tion* and stabilhy in the region* of param etric reaonance of first and sacond order* are datermined. Solutions outskJe the region* of pa ram etric resonances are approximated by two limit cycles.

MECHANICAL PROPERTIES

DAMPING

(Also *ee Nos. 1578. 1632,1640)

84-1789

Uaefalneas of Impact Dam per* for Spaee Application*

B.W. Gibson

School of Engrg., Air Force Inst. of Tech., Wright-Patterson AFB, OH. Rept. No. AFIT/GA/AA/83M-2. 147 pp (Mar 1983)

AD-A135 695

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84-1788

Parametric Excitatk>n in the Sełf-Excited Yibration System with Dry Friction (2nd Report, In the Neifh-borhood of the Region of Pirometrie Reaonance)

S. Yano

Fukui Univ., 3-9-1, Bunkyo, Fukui, Japan. Buli. JSME, 22 (224). pp 263-270 (Feb 1984) 13 figs. 2 refs

Key Word*: Shock absorber*, Experimental data, Computer ized simuietion

The usefulness of the impact damper in eliminating vibratk>nt 1* studied anaiytically and experimentally. Laboratory modeli of vibrating system* are constructed to evatuate the performance of the impact damper in reducing or eliminating forced and fraa vibrations. A Computer simuietion of a single dagrea-of-freedom primary system in free yibration amploying an impact damper is constructed for the same purpose. Laboratory free yibration results are compered to the Computer simuietion in order to judge rts accurecy.

Key Word*: Parametric excłtetion. Coulomb friction. Para metric resonance, Crltłcal apaads

In paramatrically excKed *elf-excitatlon system* with dry friction, approximat# Solutions outsida tha region* of parametric resonance of sacond order are obteined. Approximate Solutions in the neighborhood of parametric resonance of first order era obteined and crKicał frequencies where beat ybrations occur and diwppaar cen ba datarminad by tha point* of intarseetlon of thase *o lut toni and parametric resonance curves of first order. By numsrical resuKs K is ascartalnad that this determinetlon method of crklcal fre-quencies has high accurecy and tha interactlon between parametric excKation and se!f-exched yibration is dlscusaad.

84-1790

Initial Fatimates of Darapin* Ratea and Freauencies

T.G. Ryall

Aeronautical Res. Labs., Melbourne. Australia, Rept. No. ARL-STRUC-NOTE-485, AR-002-943. 13 pp (Mar 1983)

N84-13879

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THERMAL EXCITATION

(Saa Nos. 1768.1760)

Kay Word*: Camping coefficlents. Fourier transformation

Natural freguencies.

A lim ple, quick method for obtaining fraquencies and damplng rattoi from Fourier transforms was devised. Singla pola-slngla zero approximation, equetk>n of Nyquist tocut, and two zeros-two pola* epproximetton ara addrtseed.

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