Fatigue life prediction in frequency domain using thermal-acoustic loading test results of titanium specimen

2020 ◽  
Vol 34 (10) ◽  
pp. 4015-4024
Author(s):  
Eun-Su Go ◽  
Mun-Guk Kim ◽  
In-Gul Kim ◽  
Min-Sung Kim
Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1587 ◽  
Author(s):  
Krzysztof Kluger ◽  
Aleksander Karolczuk ◽  
Szymon Derda

This study presents the life-dependent material parameters concept as applied to several well-known fatigue models for the purpose of life prediction under multiaxial and non-zero mean loading. The necessity of replacing the fixed material parameters with life-dependent parameters is demonstrated. The aim of the research here is verification of the life-dependent material parameters concept when applied to multiaxial fatigue loading with non-zero mean stress. The verification is performed with new experimental fatigue test results on a 7075-T651 aluminium alloy and S355 steel subjected to multiaxial cyclic bending and torsion loading under stress ratios equal to R = −0.5 and 0.0, respectively. The received results exhibit the significant effect of the non-zero mean value of shear stress on the fatigue life of S355 steel. The prediction of fatigue life was improved when using the life-dependent material parameters compared to the fixed material parameters.


2018 ◽  
Vol 7 (3.17) ◽  
pp. 104
Author(s):  
Chin Chuin Hao ◽  
Shahrum Abdullah ◽  
Ahmad Kamal Ariffin ◽  
Salvinder Singh Karam Singh

This paper aims to predict the durability of an automobile coil spring by characterising the captured strain data. The load histories collected at coil spring are often presented in time domain but time domain cannot provide sufficient information for fatigue life prediction. The objective of this study was to characterise the strain signal in time domain, frequency domain and time-frequency domain for fatigue life prediction. The signal obtained in time domain was used to predict the fatigue life of the coil spring through Rainflow cycle counting technique and models of strain-life relationships. In frequency domain, fast Fourier transform revealed that the frequency components in the strain signal ranged between 0-5 Hz. The frequencies can be further categorised into two ranges: 0-0.3 Hz and 1-2 Hz. Power spectral density confirmed that the frequencies with high energy content were 0-5 Hz and the total energy content in the signal is 4.0872x103 µɛ2. Short time Fourier transform can identify the local time and frequency properties of the signal but it has a limitation in time-frequency resolutions. Wavelet transform can provide a better time-frequency resolutions and it confirmed that the transients in the time domain had frequency range of 1-2 Hz. In summary, this study revealed different possible approaches of signal processing in fatigue life assessment of automotive components as guidance for the selection of suitable approach based on the type of information needed for the analysis.  


2014 ◽  
Vol 692 ◽  
pp. 387-390
Author(s):  
Qiu Rong Ma ◽  
Yang Li ◽  
Kun Yang

This paper researched the test of fatigue crack propagation of grade X80 submerged arc welded pipes. According to the test results, analyzed and calculated the fatigue life of submerged arc welded pipes for X80 with half elliptical crack defects at the simulated work condition of shutdown. On a single simulated work condition, the fatigue life of submerged arc welded pipes for X80 with Ф1219×22.0mm is 62 years, which had enough safety margin for fatigue life.


2014 ◽  
Vol 891-892 ◽  
pp. 1347-1352
Author(s):  
Norio Takeda ◽  
Tomohiro Naruse

This study focuses on the method of predicting the fatigue life of materials subjected to random loading. Since random stress caused by random loading is rigorously expressed in the frequency domain as stress power spectral density (PSD), fatigue life should be predicted using stress PSD. We propose two adjustment methods of improving the accuracy of fatigue life prediction using stress PSD in the frequency domain. The method proposed by Dirlik is widely used for predicting the fatigue life in the frequency domain; however, it overestimates fatigue damage caused by large stress amplitude when the slope of the fatigue resistance curve is large. To prevent this overestimation, we applied our two adjustment methods to fatigue life prediction for typical random stresses observed on mechanical products. As a result, the adjustment methods worked well in improving prediction accuracy. Lightweight and reliable products can be therefore designed by applying the proposed methods to the evaluation of fatigue life under random loading.


Author(s):  
Jun Shi

This paper summaries two sets of tension-tension fatigue results. The first set corresponds to low R ratio (0.1) and low frequency (1Hz), whereas the second set covers high R ratio (0.9) and high frequency (10Hz). For the former, detailed analysis of stress strain loops is conducted in connection with the underlying mechanisms that govern fatigue deformation and life. For the latter only stiffness variation with fatigue cycles is discussed. The test results are also examined for their impact on fatigue life prediction.


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