On field durability tests of mechanical systems. The use of the Fatigue Damage Spectrum

In this study, a non-Gaussian excitation acceleration method is proposed, using aluminum alloy notched specimens as a research object and measured acceleration signal of a certain airborne bracket, during aircraft flight as input excitations, based on the fatigue damage spectrum (FDS) theory. The kurtosis and skewness of the input signal are calculated and the non-Gaussian characteristics and amplitude distribution are evaluated. Five task segments obey a non-Gaussian distribution, while one task segment obeys a Gaussian distribution. The fatigue damage spectrum calculation method of non-Gaussian excitation is derived. The appropriate FDS calculation method is selected for each task segment and the acceleration parameters are set to construct the acceleration power spectral density, which is equivalent to the pseudo-acceleration damage. A finite-element model is established, the notch stress concentration factor of the specimen is calculated, the large mass point method is used to simulate the shaking table excitation, and a random vibration analysis is carried out to calculate the accelerated fatigue life. The simulation results show that the relative error between the original cumulative damage and test original fatigue life is 15.7%. The shaking table test results show that the relative error of fatigue life before and after acceleration is less than 16.95%, and the relative error of test and simulation is 24.27%. The failure time of the specimen is accelerated from approximately 12 h to 1 h, the acceleration ratio reaches 12, and the average acceleration ideal factor is 1.125, which verifies the effectiveness of the acceleration method. It provides a reference for the compilation of the load spectrum and vibration endurance acceleration test of other airborne aircraft equipment.

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“…Under the assumption of small damping, n + 0 ≈ f 0 . en substitute ( 13) into (11) to derive the FDS expression [8]:…”

Section: Gaussian Frequency Domain Fatigue Damage Modelsmentioning

confidence: 99%

“…is ensured that the accelerated endurance test could reproduce the fatigue load characteristics of the tractor assembly. Based on FDS and test synthesis method, Cianetti [11] compared the fatigue damages caused by acceleration excitation under different conditions and verified the proposed acceleration method by a durability test case.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Life Analysis of Aluminum Alloy Notched Specimens under Non‐Gaussian Excitation based on Fatigue Damage Spectrum

Chen

Yang

Zhang

et al. 2021

Shock and Vibration

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“…To determine the effects of damping ratio and fatigue exponent on the calculation of response spectra and PSD synthesis, the pseudovelocity FDS of field data were calculated with different values of Q (10, 25, 50) and b (4,8,12), as shown in Figure 7. From Figure 7, we can see that the FDS decreases and the dispersion increases, as the value of b increases.…”

Section: Fatigue Damage Spectrum (Fds) and Extreme Response Spectrum (Ers)mentioning

confidence: 99%

“…To address this problem, the response spectrum method was utilized to evaluate the potential damage introduced by the vibration environment. An accelerated test spectrum was then synthesized from the response spectra based on the damage equivalence criterion [11][12][13]. To perform life cycle potential damage assessment and test tailoring, Lalanne [14] derived an equivalent PSD from multiple task profiles based on the frequency domain fatigue damage spectrum (FDS).…”

Section: Introductionmentioning

confidence: 99%

Optimization of Damage Equivalent Accelerated Test Spectrum Derivation Using Multiple Non‐Gaussian Vibration Data

2021

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The response spectra are widely used in the damage assessment of non-Gaussian random vibration environments and the derivation of damage equivalent accelerated test spectrum. The effectiveness of the latter is strongly affected by modal parameter uncertainties, multiple field data processing, and the nonsmooth shape of the derived power spectral density (PSD). Optimization of accelerated test spectrum derivation based on dynamic parameter selection and iterative update of spectrum envelope is presented in this paper. The extreme response spectrum (ERS) envelope of the field data is firstly taken as the limiting spectrum, and the corresponding relationship between damping coefficient, fatigue exponent, and damage equivalent PSD under different test times is constructed to achieve the dynamic selection of uncertain parameters in the response spectrum model. Then, an iterative update model based on the weighted sum of fatigue damage spectrum (FDS) error is presented to reduce the error introduced by the nonsmooth shape of the derived PSD. The case study shows that undertest can be effectively avoided by the dynamic selection of model parameters. The weighted error is reduced from 80.1% to 7.5% after 7 iterations. Particularly, the error is close to 0 within the peak and valley frequency band.

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The Effect of Load Phase Angle on Roof Components of Electric Driven Bus Fatigue Damage

Sönmez

2021

Exp Tech

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On field durability tests of mechanical systems. The use of the Fatigue Damage Spectrum

Cited by 5 publications

References 8 publications

Fatigue Life Analysis of Aluminum Alloy Notched Specimens under Non‐Gaussian Excitation based on Fatigue Damage Spectrum

Fatigue Life Analysis of Aluminum Alloy Notched Specimens under Non‐Gaussian Excitation based on Fatigue Damage Spectrum

Optimization of Damage Equivalent Accelerated Test Spectrum Derivation Using Multiple Non‐Gaussian Vibration Data

The Effect of Load Phase Angle on Roof Components of Electric Driven Bus Fatigue Damage

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