The effort of the dynamic simulation on the fatigue damage evaluation of flexible mechanical systems loaded by non-Gaussian and non stationary loads

Abstract Even if in fatigue application it is common to assume stationary and Gaussian excitation, the impact of non-Gaussian and non-stationary loadings on the service life of a mechanical component is known. Non-Gaussian and non-stationary excitations are generally observed in several industrial applications (i.e. automotive, aeronautical, etc.) and for this, the assessment of the effect of such loads results necessary. From this assumption, the activity herein presented starts from experimental results, previously obtained, that analysed the influence of non-Gaussianity (generally evaluated by kurtosis) and of non-stationarity of inputs on the fatigue life of an Y-shaped specimen. In the present paper the finite element model of the sample and its full validation obtained by numerical/experimental comparison is presented. Moreover, due to the relevant effect of the system’s dynamics on the stress/strain response previously observed, a wider assessment of non-Gaussianity and non-stationarity influence on the fatigue life has been numerically analysed together with the influence of the multi modal behaviour of the component by adopting an excitation frequency range that excites two modes of the model.

[1]  M. Baker,et al.  On the probability density function of rainflow stress range for stationary Gaussian processes , 1992 .

[2]  J. Collins.  Failure of materials in mechanical design : analysis, prediction, prevention , 1981 .

[3]  J. Bendat,et al.  Random Data: Analysis and Measurement Procedures , 1987 .

[4]  O. Basquin.  The exponential law of endurance tests , 1910 .

[5]  Denis Benasciutti,et al.  Fatigue life assessment in non-Gaussian random loadings , 2006 .

[6]  Turan Dirlik,et al.  Application of computers in fatigue analysis , 1985 .

[7]  Janko Slavič,et al.  Frequency-domain methods for a vibration-fatigue-life estimation – Application to real data , 2013 .

[8]  Janko Slavič,et al.  Non-Gaussianity and non-stationarity in vibration fatigue , 2017 .

[9]  D. Smallwood.  Generating Non-Gaussian Vibration for Testing Purposes , 2005 .

[10]  D. Newland.  An introduction to random vibrations and spectral analysis , 1975 .

[11]  Janko Slavič,et al.  Multiaxial vibration fatigue—A theoretical and experimental comparison , 2016 .

[12]  Claudio Braccesi,et al.  Random fatigue. A new frequency domain criterion for the damage evaluation of mechanical components , 2015 .

[13]  Vincent Rouillard,et al.  Simulation of non-stationary vehicle vibrations , 2001 .

[14]  André Preumont,et al.  Spectral methods for multiaxial random fatigue analysis of metallic structures , 2000 .

[15]  Claudio Braccesi,et al.  Development of selection methodologies and procedures of the modal set for the generation of flexible body models for multi-body simulation , 2004 .

[16]  André Preumont,et al.  Random Vibration and Spectral Analysis , 2010 .

[17]  Hank Caruso.  MIL-STD-810F, Test Method Standard for Environmental Engineering Considerations and Laboratory Tests , 2001 .

[18]  Claudio Braccesi,et al.  An equivalent uniaxial stress process for fatigue life estimation of mechanical components under multiaxial stress conditions , 2008 .

[19]  Claudio Braccesi,et al.  An innovative modal approach for frequency domain stress recovery and fatigue damage evaluation , 2016 .

[20]  Giuliano Allegri,et al.  On the inverse power laws for accelerated random fatigue testing , 2008 .

[21]  Stuart L Grassie,et al.  Rail irregularities, corrugation and acoustic roughness: characteristics, significance and effects of reprofiling , 2012 .

[22]  Katrin Baumgartner.  Failure Of Materials In Mechanical Design Analysis , 2016 .

[23]  Frédéric Kihm,et al.  Understanding How Kurtosis Is Transferred from Input Acceleration to Stress Response and Its Influence on Fatigue Llife , 2013 .

[24]  S. Winterstein.  Nonlinear Vibration Models for Extremes and Fatigue , 1988 .

[25]  Mehrdad Raisee,et al.  Load variation effects on the pressure fluctuations exerted on a Kaplan turbine runner , 2014 .

[26]  Peter Wolfsteiner,et al.  Fatigue assessment of non-stationary random vibrations by using decomposition in Gaussian portions , 2017 .

[27]  Adam Niesłony,et al.  The Use of Spectral Method for Fatigue Life Assessment for Non-Gaussian Random Loads , 2016 .

[28]  W. Brogan.  Modern Control Theory , 1971 .

[29]  Janko Slavič,et al.  Multiaxial Fatigue Criteria for Random Stress Response – Theoretical and Experimental Comparison , 2015 .

[30]  Denis Benasciutti.  Fatigue analysis of random loadings: A frequency-domain approach , 2012 .

[31]  Claudio Braccesi,et al.  Evaluation of mechanical component fatigue behavior under random loads: Indirect frequency domain method , 2014 .

[32]  Claudio Braccesi,et al.  The frequency domain approach in virtual fatigue estimation of non-linear systems: The problem of non-Gaussian states of stress , 2009 .

[33]  Stephen A. Rizzi,et al.  On the Response of a Nonlinear Structure to High Kurtosis Non-Gaussian Random Loadings , 2011 .