Variable Amplitude Fatigue Life Prediction of Rock Samples Under Completely Reversed Loading
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ORIGINAL PAPER
Variable Amplitude Fatigue Life Prediction of Rock Samples Under Completely Reversed Loading Hadi Haghgouei . Alireza Baghbanan . Hamid Hashemolhosseini . Saeed Jamali
Received: 10 April 2020 / Accepted: 8 October 2020 Ó Springer Nature Switzerland AG 2020
Abstract Many rock structures may experience cyclic loading with variable amplitude. Therefore, considering the fatigue behavior of rocks subjected to different loading sequences is necessary. In this study, the accumulated fatigue damage for a Green onyx rock sample with two-step high to low sequences of loading levels was investigated under completely reversed loading condition. In order to apply completely reversed loading to the rock specimens, a new rotating fatigue test machine is employed. A comparison between the predicted behavior of Manson damage curve approach and experimental data was conducted. The results showed that the applicability of Manson damage curve approach depends on the fatigue life ratio of specimens subjected to high-low loading conditions. A new damage curve model was proposed based on the experimental observation and verified with a large number of laboratory tests. Also, the H. Haghgouei (&) A. Baghbanan S. Jamali Department of Mining Engineering, Isfahan University of Technology (IUT), 84156-83111 Isfahan, Iran e-mail: [email protected] A. Baghbanan e-mail: [email protected] S. Jamali e-mail: [email protected] H. Hashemolhosseini Department of Civil Engineering, Isfahan University of Technology (IUT), 84156-83111 Isfahan, Iran e-mail: [email protected]
results manifested the higher loading level plays a significant role in the fatigue life of samples. Since the amplitude of the dynamic load conducted on the rock structures is not constant, it is necessary that variable amplitude loading to be taken into account. Otherwise, the prediction of fatigue life is overestimating. Keywords Cumulative damage Variable amplitude loading Completely reversed loading Stress-life method Fatigue of rocks
1 Introduction Fatigue is termed as the progressive failure of the materials by the growth of cracks under cyclic loading (Budynas and Nisbett 2008) which leads sample to fail at much lower loading compared to its static strength (Vaneghi et al. 2018). A large number of structures such as tunnel walls, foundation of roads and dams, the abutments of bridge and geo-storage reservoirs are subjected to fatigue stress (Bagde and Petrosˇ 2009; Chen et al. 2011; Liu et al. 2014; Perazzelli and Anagnostou 2016). However, the study of rock fatigue is limited, and therefore, the behavior of rocks under cyclic loading is not completely clear. The fatigue damage can be investigated by considering the change in different parameters or properties under cyclic loading, for example, elastic modulus(Chen et al. 2012; Lemaitre 1985; Xiao et al. 2010),
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Geotech Geol Eng
irreversible strain(Li et al. 2003), residual volumetric strain (Liu et al. 2012), energy dissi
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