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Twenty-seven papers from fatigue researchers and practitioners review in detail recent progress in the development of methods to predict fatigue performance of materials and structures and to assess the extent to which these new methods are finding their way into practice. The papers, from the ASTM
In order to minimize the expenses of the development of engineering components and to reduce the risk of their operation, reliable fatigue life prediction methods have to be available in the design stage. Presently two groups of methods can be distinguished which explicitly account for the local stresses/strains in the fatigue critical areas: the so-called notch analysis concepts or "local approaches," and new developments which are based on finite element methods (FEM).
Narrow-band random-amplitude and constant-amplitude bending fatigue tests were conducted on sharply notched Rene' 41 specimens at room temperature, 700 degrees F (644 degrees K), and 1400 degrees F (1033 degrees K). When compared on the basis of the root mean square of the nominal peak stresses, the random loading generally gave shorter lives than the constant-amplitude loading. Theoretical life predictions were made for the random-loading tests by using the Palmgren-Miner cumulative-damage rule and two different peak stress distributions (the distribution determined from the tests and the classical Rayleigh distribution). The predictions under-estimated the fatigue life in practically all cases. The predicted lives based on the Rayleigh peak distribution were always less than those predicted by using the experimentally determined peak distribution. For both types of loading in the long-life region, a loss of fatigue strength from that at room temperature occurred at 700 degrees F (644 degrees K) but no further loss occurred at 1400 degrees F (1033 degrees K).
This book covers the development of innovative computational methodologies for the simulation of steel material fracture under both monotonic and ultra-low-cycle fatigue. The main aspects are summarised as follows: i) Database of small and full-scale testing data covering the X52, X60, X65, X70 and X80 piping steel grades. Monotonic and ULCF tests of pipe components were performed (buckled and dented pipes, elbows and straight pipes). ii) New constitutive models for both monotonic and ULCF loading are proposed. Besides the Barcelona model, alternative approaches are presented such as the combined Bai-Wierzbicki-Ohata-Toyoda model. iii) Developed constitutive models are calibrated and validated using experimentally derived testing data. Guidelines for damage simulation are included. The book could be seen as a comprehensive repository of experimental results and numerical modeling on advanced methods dealing with Ultra Low Cycle Fatigue of Pipelines when subjected to high strain loading conditions.