A NEW METHOD FOR FATIGUE TESTING AND DATA PRESENTATION: AN ILLUSTRATION ON SOME METALLIC CERAMIC AND POLYMER MATERIALS D. G. Angelova The University of Chemical Technology and Metallurgy, Sofia, Bulgaria ABSTRACT In this study a new method for fatigue testing and data presentation has been proposed, which is based on a reduced number of data readings during a fatigue test. This method represents the experimental results obtained at a given stress range linearly and shows possibilities for shortening testing times and making fatigue analyses and predictions more precise. The paper describes how the method works for representing fatigue in a high-strength spring steel. Some preparatory work has been done towards showing the applicability of the proposed method to different kinds of Al2O3 ceramic and a PC polymer. INTRODUCTION Since the Paris equation appeared in the early 1960’s many attempts have been made to present fatigue phenomenon by simple models. Some, for example those of Forman [1] and Walker [2], have been proposed to account for the load ratio dependence of fatigue crack growth rate and the distinction of crack growth behaviour in the near-threshold and final-failure regimes from that in the intermediate one. Summarizing, if R-ratio effects are taken into consideration, an accurate description of the whole fatigue behaviour of a given material needs about ten empirical constants after Dowling [3]. Other models, especially those of short fatigue crack propagation of Brown-Hobson [5] and Navarro-de los Rios [4], have been introduced to represent crack growth rates through the decreasing crack growth falls at the fatigue thresholds, Miller [6]. Some later modifications of these models describe accurately: corrosion fatigue behaviour, Akid-Murtaza [7]; a physically small crack growth regime separately from a short crack growth regime by a new equation, Angelova-Akid [8]; fatigue crack coalescence, Brown et al. [9]. Lately a new alternative approach has been introduced revealing a specific tendency of metal fatigue behaviour, expressed
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