Life estimation model of a cantilevered beam subjected to complex random vibration

ABSTRACT An analytic methodology was developed to predict the fatigue life of a structure ex-periencing stationary, Gaussian random vibration excitation. This method allows theestimation of fatigue life using a frequency domain method, where only the input powerspectral density and damping factor are required. The methodology uses linear elasticfracture mechanics for fatigue crack propagation and accounts for the frequency shiftingthat occurs due to fatigue crack evolution. Good results have been obtained comparingthe analytic model to both finite element analysis (FEA) and experimental results, formild-steel cantilever beams. Keywords damageaccumulation;fatigue;fracture;frequencyshift;powerspectralden-sity; random vibration.NOMENCLATURE A = constant a = crack depth a f = final crack depth C = Paris law constant C ray = statistical correction factor c = half height of rectangular cross-section D ray = equivalent damage constant d = notch depthd a /d N = crack growth rate dt = differential time

[1]  Murat Aykan,et al.  Vibration fatigue analysis and multi-axial effect in testing of aerospace structures , 2009 .

[2]  L. Meirovitch,et al.  Fundamentals of Vibrations , 2000 .

[3]  J. Srawley.  Wide range stress intensity factor expressions for ASTM E 399 standard fracture toughness specimens , 1976, International Journal of Fracture.

[4]  Warren C Fackler.  EQUIVALENCE TECHNIQUES FOR VIBRATION TESTING , 1972 .

[5]  Wayne E. Whiteman,et al.  Inadequacies in Uniaxial Stress Screen Vibration Testing , 2001 .

[6]  J. Congleton,et al.  Failure of materials in mechanical design, 2nd edition , 1994 .

[7]  R. M. French,et al.  A comparison of simultaneous and sequential single-axis durability testing , 2006 .

[8]  Basim Al-Najjar,et al.  ACCURACY, EFFECTIVENESS AND IMPROVEMENT OF VIBRATION-BASED MAINTENANCE IN PAPER MILLS: CASE STUDIES , 2000 .

[9]  M. S. Lebold,et al.  A spectral simulation approach to evaluate probabilistic measurement precision of a reactor coolant pump torsional vibration shaft crack monitoring system , 2008 .

[10]  Dave S. Steinberg.  Preventing Thermal Cycling and Vibration Failures in Electronic Equipment [Book Review] , 2005, IEEE Circuits and Devices Magazine.

[11]  D. Bergez.  Linear elastic fracture mechanics applied to cracked plates and shells , 1976 .

[12]  Mark Paulus.  Limitations of the Power Spectral Density as an Indicator of Test Severity , 2011 .

[13]  Leontios J. Hadjileontiadis,et al.  Time–frequency analysis of the free vibration response of a beam with a breathing crack , 2005 .