Browsing by Keyword "Random loading"
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Item A plain linear rule for fatigue analysis under natural loading considering the sequence effect(2017-10) Calderon-Uriszar-Aldaca, I.; Biezma, M.V.; Tecnalia Research & InnovationFatigue under variable amplitude loading is currently assessed with the Palmgren-Miner rule in structural standards, ignoring the order of loading, which would require non-linear or mixed rules, especially for the random loading sequences applied to certain structures. Therefore, the goal is to develop a practical and simple correction factor ensuring the linear summation of damage is conservative, so as to take the sequence effect into account in random loading from natural sources. The theoretical consistency of this approach is demonstrated and a case study is developed to test the feasibility of the new rule and its simplicity.Item Second-order fatigue of intrinsic mean stress under random loadings(2020-01) Calderón-Uríszar-Aldaca, Iñigo; Biezma, María Victoria; Matanza, Amaia; Briz, Estibaliz; Bastidas, David M.; Tecnalia Research & InnovationA fatigue process due to random loading that is progressively damaging a certain structural detail will vary in the presence of mean stresses. The variations are already considered in crack propagation laws and by applying equivalent 0-mean stress ranges from the Palmgren–Miner linear rule. Nevertheless, if the mean stress is intrinsic, instead of a direct consequence of the random loading, other second-order effects will have to be taken into account. Those effects are cycle quasi-ordering, histogram variations, and apparent mean tension, which are identified and defined in this study and, finally, developed in a case study for demonstrative purposes.