“Projection-by-Projection” Approach: A Spectral Method for Multiaxial Random Fatigue

Cristofori, Alessandro; Benasciutti, Denis

doi:10.4271/2014-01-0924

Cited by 16 publications

(26 citation statements)

References 15 publications

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“…The shear stress amplitudes, E t * a Â Ã or E ffiffiffiffiffiffi ffi J 2;a p Â Ã , must be calculated according to the conventional [43] x x Projection-by-Projection [47,48] x x x x…”

Section: Multiaxial Loadingsmentioning

confidence: 99%

Frequency‐based analysis of random fatigue loads: Models, hypotheses, reality

Benasciutti

Tovo

2018

Materialwissenschaft Werkst

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Spectral methods use analytical expressions to estimate the fatigue damage in vibrating structures subjected to uniaxial or multiaxial random stresses. They exploit the random vibration theory which idealizes the random stress as a random process characterized by a power spectral density (PSD) in the frequency‐domain. The random process is hypothesized to be stationary or non‐stationary, Gaussian or non‐Gaussian, and with narrow‐band or wide‐band power spectral density. The accuracy of analytical spectral solutions depends on whether such hypotheses are fulfilled by actual random time‐histories encountered in practice. Knowing the range of applicability of each spectral method is then of utmost importance to avoid estimation errors. After a short account on the frequency‐domain description of random processes, this paper presents a brief survey on selected spectral methods for uniaxial and multiaxial random loading. It then analyzes when the hypotheses behind each spectral method are not verified in reality, with the purpose to provide recommendations for a safe use of frequency‐based methods.

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“…The shear stress amplitudes, E t * a Â Ã or E ffiffiffiffiffiffi ffi J 2;a p Â Ã , must be calculated according to the conventional [43] x x Projection-by-Projection [47,48] x x x x…”

Section: Multiaxial Loadingsmentioning

confidence: 99%

Frequency‐based analysis of random fatigue loads: Models, hypotheses, reality

Benasciutti

Tovo

2018

Materialwissenschaft Werkst

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“…Similarly to the A-Z solution (15), the ratio of time durations can be further manipulated to obtain: in which superscript (e) reminds that quantities refer to element (e) in the finite element model. Equation (19) is the bandwidth correction of the original A-Z solution (15). Compared to Eq.…”

Section: Bandwidth Correction Of A-z Solutionmentioning

confidence: 99%

“…Allegri and Zhang also demonstrated that Eq. (15) returns exactly the scaling law (1) in the special case in which the acceleration PSD for the "lab" environment is simply scaled with respect to that characterising the "real" environment [3]. It has to be emphasised that the scaling law (15) is based on the hypothesis to take N 0 as a measure of the number of rainflow cycles, which is exact only for a narrow-band stress (where ν 0 ≅ν p ).…”

Section: Accelerated Tests and Scaling Law 41 Allegri-zhang (A-z) Ormentioning

confidence: 99%

“…the inverse of fatigue damage) for each stress projection is estimated by the TB method for wide-band stress (see Eq. (8) [14,15]). To appreciate the effect of S-N parameters, Fig.…”

Section: Fig 10 Distribution Of Log(t S ) (Case 1) By Pbp Criterionmentioning

confidence: 99%

“…A proposal is made here to reformulate the A-Z scaling law by using the so-called "Projection-by-Projection" (PbP) criterion, which is a stress invariant-based multiaxial criterion that can account for both torsion and tension S-N parameters (the main theoretical aspects are outside the goal of this work and they can be found elsewhere [14,15]). The PbP method computes the fatigue damage in time T as: (20) where d i is the damage intensity (damage/s) of the i-th stress projection in the deviatoric space, which can be estimated by uniaxial spectral methods, see Section 3.1.…”

Section: Fig 10 Distribution Of Log(t S ) (Case 1) By Pbp Criterionmentioning

confidence: 99%

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A bandwidth correction to the Allegri-Zhang solution for accelerated random vibration testing

2018

Self Cite

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Abstract. In 2008, Allegri and Zhang published a study [Int. J. Fatigue. 2008, 30(6):967-977] in which they provided an exact analytical solution to the inverse scaling law for accelerated vibration tests of linear systems submitted to stationary Gaussian excitations By combining finite element analysis with multiaxial spectral methods defined in the frequency-domain, their solution generalised the simple inverse power law model suggested in some standards. The solution adopted the "equivalent von Mises stress" multiaxial criterion combined with the narrow-band damage expression. This work aims to propose a bandwidth correction to the original Allegri-Zhang solution to account for the actual spectral bandwidth of the local multiaxial stress. The corrected Allegri-Zhang solution is also extended to another multiaxial spectral method, namely the "Projection-by-Projection" criterion. A numerical example is finally discussed, in which the corrected solution is applied to an L-shaped beam submitted to random accelerations.

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Estimation of fatigue life under random multiaxial conditions using the projection-by-projection method

Cardoso

Ferreira

2022

J Braz. Soc. Mech. Sci. Eng.

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“Projection-by-Projection” Approach: A Spectral Method for Multiaxial Random Fatigue

Cited by 16 publications

References 15 publications

Frequency‐based analysis of random fatigue loads: Models, hypotheses, reality

Frequency‐based analysis of random fatigue loads: Models, hypotheses, reality

A bandwidth correction to the Allegri-Zhang solution for accelerated random vibration testing

Estimation of fatigue life under random multiaxial conditions using the projection-by-projection method

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