On Applying the Neuber’s Rule to Spectral Fatigue Damage Estimation Under Elasto-plastic Strain A. Kara1,∗, D. Benasciutti2 1 Department of Mechanical Engineering, Istanbul Technical University, Istanbul 34437, Turkey 2 Department of Engineering, University of Ferrara, Ferrara 44122, Italy ∗ aliyye.kara@itu.edu.tr Keywords: Spectral fatigue, plasticity, strain-based spectral damage Spectral methods (frequency domain approaches) are commonly used for estimating fatigue damage of vibrating structures in high-cycle fatigue regime, where the material is linear elastic [1]. In the low-cycle fatigue regime, by contrast, material exhibits plasticity, so the structural response is non-linear. For this reason, the applicability of spectral methods in low-cycle fatigue regime is open to debate. Few studies exist in the literature that include plasticity in the spectral methods by means of the Neuber’s rule and the Ramberg-Osgood constitutive model [2, 3]. The Neuber’s rule approximates the elasto-plastic stress and strain responses by using the stress and strain results of an elastic analysis. This paper aims to provide a critical analysis of the existing strain-based spectral methods based on Neuber’s rule. After developing a rigorous theoretical formulation, the spectral damage estimations are compared with simulation results obtained in the time domain by the use of cyclic plasticity models with kinematic and isotropic hardening effects (Chaboche and Voce models). The findings allow us to shed light on the range of applicability of the existing strain-based spectral methods, while also providing ideas for possible further improvements. References [1] Lutes, L. D., Sarkani, S. (2004). Random vibrations: analysis of structural and mechanical systems. Butterworth-Heinemann. [2] Rognon, H., Botelho, T. D. S., Tawfiq, I., & Bennebach, M. (2014). Spectral methods plasticity modeling for fatigue damage estimation: experimental application–uniaxial case. Mechanics & Industry, 15(3), 233–242. [3] Böhm, M., Kowalski, M., & Niesłony, A. (2020). Influence of the elastoplastic strain on fatigue durability determined with the use of the spectral method. Materials, 13(2), 423. 46
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