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fatigue stress intensity range values, AKth, were assessed. Essentially the extent of the R-ratio response on AKth was found to be significantly microstructure-dependent but the trends were by no means simple. Generally the predictions of the various models dealing with R-ratio-AKth trends exhibited poor commonality with the experimentally determined AKth values. Marked complex yield strength try effects on AKth were observed at low Rratio levels (R approx = 0): (a)AKth levels initially increased with try, (b) attained a maximum AK~h value of 9 MPa m It2 which remained constant with increasing try level over the range 300-500 MPa and (c)above o~v approx = 600 MPa AKtt, decreased with try. Graphs, photomicrographs, 35 ref. Fatigue crack growth prediction for spectrum Ioadings using neural networks. Pidaparti, R.M.V. and Palakal. M. (Purdue University) Proc. 34th AIAAIASMEIASCEIAHS/ASC Structures, Structural Dynamics, and Materials Conference; AIAAIASME Adaptive Structures Forum V, La Jolla, California, USA (19-22 Apr. 1993) 2654-2660 An artificial neural network method is developed to represent the fatigue crack growth and cycle relationships under different spectrum loadings. The method utilizes load cycle spectrum using available flight data and experimental data for growth vs. cycles as input. The trained network is able to predict the relationship between the crack growth and loading cycles in centrecracked panel specimens of 7075 aluminium alloy. The neural network is able to generalize the crack growth-cycle behaviour for different variations in the loading spectrums. The result predicted by the neural network model seems reasonable and the model is capable of representing crack growth behaviour for arbitrary Ioadings. Graphs, 7 ref. Grain-boundary participation in high-temperature deformation: an historical review. Gifkins, R.C. Mater. Charact. (Mar. 1994) 32 (2), 59-77 A personal and historical approach is used to frame this review of the development of understanding of the role of grain boundaries in hightemperature deformation of, e.g. brass, steels, aluminium, nitrogen, zinc alloys and lead alloys. Power-law creep, creep ductility, diffusion creep, superplasticity, and high-temperature fatigue are included in the survey, as is a brief discussion of models for the grain boundary itself. Some of the principal features described are subgrains, grain-boundary sliding, cavity nucleation and growth, various kinds of localized diffusion creep, grain* boundary migration, and the core and mantle concept. Photomicrographs, graphs, 61 ref, Evaluation of fatigue damage under random stress sequences on the view point of plastic strain. Seki, H., lida, 7"., Oda, A. and lkai, Y. J. Soc. Mater. Sci. Jpn (Feb. 1994) 43 (485), 197-202 (in Japanese) Fatigue damage evaluation is one of the most important processes for the integrity of a machine or a structure. Although many trials have been made for fatigue damage evaluation, few methods can be used to deal with a wide range of stress or strain conditions of fatigue tests. The fatigue damage evaluation methods were examined with respect to plastic strain ranging from small to large amplitudes of strain repetition for a given stress sequence. Then, a new fatigue damage rule was proposed in terms of strain condition. The new rule showed agreement with the theoretical estimations for various experimental conditions. A technique was developed to obtain the stress-strain behaviour of a sample material for a given stress sequence. This showed a good applicability for fatigue damage estimation. Graphs, 5 ref.