6926475990

84*1791

Fundamenta] LnvertigatM>n on an Oil Dam per (3rd Report, Corapariaon of Anałyeee Baeed on CylindricaJ Coordinates and Carteśan Coordinates)

T. Asami and H. Sekiguchi

Himeji Inst. of Tech., 2167, Shosha, Himeji, Hyogo. 671-22, Japan. Buli. JSME. 21 (224). pp 309-316 (Feb 1984) 5 figs, 3 tables. 5 refs

K«y Wordi: Demper*. Oil dampers, Damping coefficient*

This pa per deals włth a theoretical reseerch of an oil dam per whose piston is wtorating in a viscou* fluid filling a fixed circular cylinder. In tha previous report, transforming the annular cleerance between the cylinder and the piston into a ttraight channel, the authors induced a drag force acting on the piston from an equatk>n of motion of the fluid expressad in Cartesien coordinates. Therefore the result of this analysis contained an error due to the transformation. In this report, the authors try to derive a morę exect value using an eęuetion represented in cylindrical coordinates.

84-1792

Measurement of Rolling Friction by a Damped Oacillator

M. Dayanand D.H. Buckley

NASA Lewis Res. Ctr., Cleveland. OH, Rept. No. E-1583, NASA TP-2257. 8 pp (Dec 1983)

N84-13577

Key Words: Rolling friction, Measurement techniques

An experknental method for maasuring rolling friction is proposed. The method is mechanically simple. It is based on an oscillator ina uniform megnetic field and does not inuolve any mechanical forces except for tha measured friction. The meesured pickup woltage is Fourier analyzed and yields the friction spectral response. The proposed experiment is not taiłored for a particular case. Instaad. warious modas of oparation, suitable to different experimental conditions ara discussed.

Massachusetts Inst. of Tech., Cambridge, MA 02139, ASCE J. Struć. Engrg., 110 (3), pp 461-476 (Mar 1984) 14 figs. 1 table, 24 refs

Key Words: Concretes, Cyclic loading. Fatigue life

An experimental program was conducted to study the behavior of concrete under low-cycle high amplitudę biaxial cyclic compression. 8iaxial loading was achieved by sub-jecting square concrete plates to in-plane loading where compressive stres* was applied in one direction while eon-fining the deformetion of the specimen in the orthogonal direction. Three main types of tests were performed: monotonie loading to failure; cycling of compressive stresses to a limiting envelope curve; and cycling of compressive stresses to prescribed values.

84-1794

On the Relationship Between Fatigue Limit, ThreA-old and Microstnicture of a Low-Carbon Cr-Ni Steel

Li Niań, Du Bai-ping.and Zhou Hui-jiu Res. Inst. for Strength of Materials. Xi'an Jiaotong Univ., Xi'an, Shaanxi Province. People's Rep. of China, Intl. J. Fatigue, 6. (2), pp 89-94 (Apr 1984) 13 figs, 7 tables, 5 refs

Key Words: Fatigue life. Steel

The relationship between the fatigue limit stress rangę. AOyy. the threshotd stress intensity factor, Ak^. and micro-structure of low-carbon 12CrNi3A Steel has been investi-gated. Nonpropegating microcracks were observed on the surface of smooth specimens which hed been subiected to at least 5 x 10⁶ cycles at the fatigue limit stress. The size of the cracks depertded on the characteristic size* of the microstructure of the materiał. Scanning electron microscopy showed that the fractographic characteristic* in the near-threshold region of fatigue macrocreck growth were similar to those in the fatigue microcrack inrtiation region. This implies that the fatigue limit and fatigue threshold of tha materia! have a similar physical meening, both signifying the resistance of the materiał to tha propegation of fatigua cracks.

FATIGUE

(AIsoseeNo. 1603)

84-1793

Coacrete in Biaxial Cyclic Compreasion

0. Buyukozturk and Tsi-Ming Tseng

84-1795

A Cumulative Damage Theory for Fatigue Crack Initiation and Propagation

D. Kujawski and F. Ellyin