Modeling of Plasticity in Spectral Methods for Fatigue Damage Estimation of Narrowband Random Vibrations

Abstract

In this paper, we present techniques for fatigue damage evaluation using spectral methods and a model taking into account elasto-plastic behaviour. The model is associated with a non linear fatigue law, covering the whole endurance domain (low cycle and high cycle fatigue). It uses Neuber’s method and is valid for limited plasticity. To validate this modeling, we perform a correlation between spectral methods, modified spectral methods and experimental data. We present here, the results obtained in the case of narrowband random vibrations.

Spectral methods plasticity modeling for fatigue damage estimation: experimental application – uniaxial case

“…Spectral moments determine signal parameters of 20 random processes.These results were demonstrated by 21 Rice [5]. The number of zero-upcrossings is defined in 22 equation (3).…”

“…1). In spectral domain, it is difficult to ac- 19 cess to the real strain time history, but for each strain level 20 it is possible to obtain the cycles number corresponding, 21 this is the distribution of cycles number (H function). The…”

“…4). This means that the area under the curve 36 remains the same before and after correction, only the cy-37 cles modification on the high strain modifies the damage 38 [21]. This process is integrated in the process of spectral 39 methods as shown in Figure 3.…”

“…-We will study and model the inclusion of non re- 21 versed strains (non-zero mean of the process studied).…”

Influence of the Elastoplastic Strain on Fatigue Durability Determined with the Use of the Spectral Method

“…Another limitation of the spectral method is the inability to take into account elastoplastic deformations, including the inability to include notched elements without special transformations in regards to the amplitudes. There have been some approaches to model plasticity; for example, by Rognon et al [10], but they only tested in the case of equivalent von Mises strain power spectral density (PSD). The von Mises approach has been defined for frequency domain calculations by Pitoistet and Pneumont [11].…”