
Spectral method for fatigue damage estimation with non-zero mean stress
By Pedro H. Alves CorrêaLength1h 2m
About this audiobook
This thesis consists of a fatigue study carried out on an aluminum alloy 2024-T3 in both time domain and frequency domain. Non-zero mean random signals of strain and stress are analyzed in time domain using usual Rainflow method and the damage is accumulated with the Palmgren-Miner rule, according to mean stress equations. The signals are analyzed in frequency domain using the power spectral density and the probability density function. The spectral domain analysis does not consider the negative effect of the mean stress in metal life under fatigue, so the correction factors for mean stresses developed by Goodman, Morrow, and Smith-Watson-Topper are used to change the power spectral density and, thus, the damage calculated by the probability density functions postulated by Dirlik and Tovo and Benasciutti. It is found that both Dirlik and Tovo and Benasciutti are non-conservative for a non-zero mean stress signal when comparing the damage to the one obtained in time domain analysis. When the spectral method is corrected, the results vary from Rainflow 4.9% for wide band and 6.8% for narrow band signals, always in the conservative zone, therefore predicting more damage. Tovo and Benasciutti 2 method is found to be the spectral function with the closest results when compared to the usual Rainflow method in time domain.
Audiobook details
GenreTechnology
Length1 hr 2 mins
Narrated byListen with 1,000+ voices
FormateBook with Audio
Publish dateAug 1, 2022
LanguageEnglish
Table of contents
1List of Symbols
21. Introduction
31.1 Motivation
41.2 Objectives
52. Theoretical Fundamentals
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62.1 Cyclic Loading
72.2 Fatigue of Materials
82.3 Mean Stress Correction
92.4 Rainflow Cycle Counting
102.5 Palmgren-Miner Rule
112.6 Spectral Fatigue
122.7 Random Loading
132.7.1. Stationary Random Loading
142.7.2. Ergodic Stationary Random Loading
152.7.3. Gaussian distribution
162.8 Power Spectral Density
172.9 Wide Band and Narrow Band Processes
182.10 Moments of the PSD
192.11 Fatigue Analysis Within Frequency Domain
202.11.1. The Rayleigh Method
212.11.2. Tovo-Benasciutti Method
222.11.3. Dirlik Method
232.12 Global Mean Stress Value
243. Materials and Methods
253.1 Materials and Equipment
263.1.1. Material
273.1.2. Specimen
283.1.3. Data Acquisition
293.2 Experimental Set
303.3 Signal generation
313.4 Fatigue Damage
323.5 Considering the Mean Stress
333.6 Paper Algorithm
344. Numerical and Experimental Results and Discussion
354.1 Impact test
364.2 Numerical results
374.3 Experimental Results
385. Conclusion
396. Suggestion for Future Researches
407. Appendix 1 Free Vibration of a Cantilever Bean
418. References