What is the Effect of Low Frequency Fatigue on Structural Damage?

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SUMMARY

The discussion focuses on the impact of low-frequency fatigue on structural damage, specifically in the context of a plough rod element. The author utilized Miner’s rules to calculate structural damage from a measured loading history, which exhibited a low-frequency component below 0.15Hz due to soil texture variability. After applying a high-pass filter with a cut-off frequency of 0.4Hz, the calculated damage was reduced by a factor of four compared to the unfiltered signal. This raises questions about the appropriateness of removing low-frequency variations and the threshold below which stress can be considered static.

PREREQUISITES
  • Understanding of Miner’s rules for fatigue analysis
  • Knowledge of signal processing techniques, specifically high-pass filtering
  • Familiarity with load PSD (Power Spectral Density) analysis
  • Concepts of structural damage assessment in engineering
NEXT STEPS
  • Research the application of Miner’s rules in fatigue analysis for different materials
  • Explore advanced signal processing techniques for noise reduction in load measurements
  • Investigate the effects of low-frequency loading on various structural components
  • Learn about static load assumptions and their implications in structural engineering
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Structural engineers, fatigue analysts, and researchers focused on the effects of low-frequency loading on structural integrity and damage assessment.

serbring
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fatigue: low frequency and structural damage

Hi all,

I have a measured loading history and I need to calculate the structural damage through the Miner rules. The signal is measured on a rod element of a plough. As you can see from the load PSD, the signal has a verly low frequency component (lower than 0.15Hz) due to not homogeneity of soil texture. It's like a loading history where the running mean of the load is variable. I removed the low frequency component through a high pass filter with a cut-off frequency of 0.4 and the damage is 4 times lower than the one of the not-filtered signal. So is it correct to remove the variation of the running mean? Can I say the signal has a costant running mean in terms of structural damage? What is the load frequency below that the stress is not damaging, but can be treated as a static load?

Thanks
 

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