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Inst. of Machinę Design Fundamentals. Warsaw Technical Univ., Warsaw, Narbutta 84. Poland, Intl. J. Fatigue.^(2). pp 83-88 (Apr 1984) 4 figs, 22 refs

repropegation it found to be a function of the maximum stres* intensity factor stepdown ratio. K_2max/Kt_max. Delay only occurs when this ratio is less than unity.

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Key Words: Fatigue life, Crack propagation

A method for ewluating the cumuiative damage resułting from the applicatlon of cyclic stres* (or ttrain) sequences of varying amplitudę is prasented. Both tha crack initiation and propagation itagas of tha fatigue failure proces* are included. Tha d*vełopment is be sad on the ooncept of płastic strain enargy diisipetion as a function of cyclic life. Tha damage accumutatad et any stege is evafuatad from a knowtedge of tha fatigue limit in the initiation phaseandan apparent limit obtainad through fracture mechanics for the propagation phase. The proposed damage theory is comparad wrth two-level strain cycle test data of thin-walled specimens, and is found to be in fairly good agreement.

84-1796

Effect of Environnient on the Low Cycle Fatigue Behariour of Cast Nickel-Baae SuperaUoy IN738LC

Guo Jianting, D. Ranucci. E. Picco. and P.M. Strocchi Inst. of Metal Res., Academia Sinica, Shenyang, People's Rep. of China. Intl. J. Fatigue, _6 (2). pp 95-99 (Apr 1984) 13 figs, 7 refs

Key Words: Fatigue test*. Alloys

Low cycle fatigue test* were conducted on cast nickel-bese superalloy IN738LC in vscuum and air and on *>ecimens coated with a iayar of Na Cl and Na₂S04 ^at 900°C and two diffarent strain rata*. Tha fatigue life, detarmined in terms of tha cyclic piastic strain, decreased markedly as the severity of tha anyironmant incraasad. The marked strain-rate effect found in air and mllna environments dłsappeared when the axparimants wara conducted in a vacuum.

84-1797

The Effect of Mean Stress on Delay in Fatigue Crack Growtk under Load Stepdown

D.L. McDiarmid, W. Choy, and T.M. Lee The City Univ., Northampton Square, London EC1V OHB, UK. Intl. J. Fatigue._§_(2). pp 101-105 (Apr 1984) 6 figs, 3 tables, 31 refs

Key Words: Fatigue life. Crack propagation

Tha effect of maan stras* together wrth decreasing stres* ranga on fatigue crack propagation bahavk>r in mild Steel is invastigatad. The delay period between crack arrest and 84-1798

Mtxed-Mode Fatigue Crack Growth under Biaxial Loading

R.K. Pandey and A.B. Patel

Dept. of Applied Mechanics. Indian Inst. of Tech., New Delhi-110016, India, Intl. J. Fatigue, 6_ (2), pp 119-123 (Apr 1984) 7 figs. 13 refs

Key Words: Fatigue life. Crack propagation

Studies on crack growth in a panel with an inclined crack subjected to biaxial tensile fatigue loading are presented. The strain energy density factor approach is used to characterize the fatigue crack growth. The crack growth trajectory as a function of the inłtial crack angle and the biaxiality ratio is also predicted. The analysis is applied to 7075-T6 aluminium alloy to predict the dependence of crack growth ratę on the crack angle.

84-1799

Impact and Subaequent Fatigue Damage Growth in Carbon Fibrę Laminates

W.J. Cantwell. P.T. Curtis, and J. Morton Dept. of Aeronautics, Imperial College of Science and Tech., Prince Consort Rd., South Kensington, London SW7 2BV, UK. Intl. J. Fatigue. 6_ (2). pp 113-118 (Apr 1984) 9 figs. 15 refs

Key Words: Layered meteriels. Fatigue life

The influence of the ply stacking sequence on the impact resistance and subsequent 0-tension fatigue performance of carbon fiber laminates has been investigated. Drop-weight impact tests were conducted on e rangę of 16 ply carbon fiber laminates with either all non-woven plies or mixtures of wovenand non-woven plies. Demeged coupons w. stad in O-tension fatigue for up to 10* cycles, 9canned using an ultrasonic probe and then loaded in tension until failure.

84-1800

Devek>pment of Fatigue and Crack Propagation Design and Analysis Methodology in a Corrosńre Environment for Typical MechanicaUy-Fastened Joint*. Volume 1. Phase 1 Documentation

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