scholarly journals Fatigue Test of 6082 Aluminum Alloy under Random Load with Controlled Kurtosis

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 856
Author(s):  
Robert Owsiński ◽  
Adam Niesłony
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Probability Distributions ◽  
Experimental Tests ◽  
Random Load ◽  
Additional Weight ◽  
Random Loads ◽  
Kurtosis Parameter ◽  
6082 Aluminum Alloy ◽  
Non Gaussian

This paper presents the results of experimental tests carried out on an electromagnetic shaker where the excited element was a specimen with additional weight attached to the slip table. The load was random with a different kurtosis parameter value, i.e., it was performed for non-Gaussian loads. The experiment was accompanied by basic fatigue calculations in the frequency domain and their verification with experimental results. A significant decrease in fatigue life was found to take place with an increase in kurtosis and the maintenance of the same standard deviation of the specimen load. The fatigue effect, caused by the deviation from the normal distribution that was described by the kurtosis parameter, on the fatigue life of aluminum alloy 6082 was presented. An analysis revealed the different amplitude probability distributions for the loading signal and the recorded deformation signal. It was concluded that there was a lack of sensitivity of the numerical model to the change in the kurtosis parameter of the distribution of random loads.

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

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Kuanyu Chen ◽  
Guangwu Yang ◽  
Jianjun Zhang ◽  
Shoune Xiao ◽  
Yang Xu
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Relative Error ◽  
Gaussian Distribution ◽  
Calculation Method ◽  
Shaking Table ◽  
Notched Specimens ◽  
Acceleration Method ◽  
Non Gaussian

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.

scholarly journals Experimental Research on Vibration Fatigue of CFRP and Its Influence Factors Based on Vibration Testing

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Zhengwei Fan ◽  
Yu Jiang ◽  
Shufeng Zhang ◽  
Xun Chen
Keyword(s):  
Fatigue Life ◽  
Influence Factors ◽  
Frequency Bandwidth ◽  
Load Spectrum ◽  
Vibration Testing ◽  
Random Load ◽  
Vibration Load ◽  
Fatigue Damage Accumulation ◽  
Vibration Fatigue ◽  
Non Gaussian

A new research method based on vibration testing for the vibration fatigue of FRP was proposed in this paper. Through the testing on a closed-loop controlled vibration fatigue test system, the vibration fatigue phenomenon of typical carbon-fiber-reinforced plastic (CFRP) cantilevered laminate specimens was carefully studied. Moreover, a method based on the frequency response function was proposed to monitor the fatigue damage accumulation of specimens. On the basis of that, the influence factors that affect the vibration fatigue life of CFRP were experimentally studied. The influence of amplitude probability distribution of the vibration load spectrum on the fatigue life was deeply explored. Compared with Gaussian random vibration, the non-Gaussian random load has a significant impact on the vibration fatigue life of CFRP. The experimental results also showed that the magnitude of power spectral density (PSD) has a significant effect on the vibration fatigue life of specimens. For Gaussian vibration load, the frequency bandwidth almost has no effects on the vibration fatigue life of CFRP. However, for non-Gaussian vibration load, it has a great impact on the fatigue life. When PSD magnitude and frequency bandwidth are constant, the root mean square (RMS) is proportional to the vibration fatigue life of composites.

Comparison between Fatigue Life of Autofrettage and Nonautofrettage Cylinders Using Stress Intensity Factor (KΙ)

2010 ◽  
Vol 452-453 ◽  
pp. 201-204
Author(s):  
Khalil Farhangdoost ◽  
K. Aliakbari
Keyword(s):  
Stress Intensity Factor ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Experimental Tests ◽  
Finite Element Code ◽  
Constant Ratio ◽  
Intensity Factors ◽  
Inner Surface ◽  
Final Crack

This paper provides approximate fatigue life estimates for aluminum cylinders with a constant ratio of outer to inner radii 2.2 which were subjected to autofrettage pressure. Experimental tests of cylinders made of aluminum alloy are part of this article. Numerical simulations of the cylinders were also performed using the finite element code, ABAQUS. The resulting stresses are then used to calculate stress intensity factors to determine fatigue life. Using standard fatigue crack growth relationship, life of the cylinder is then calculated based on recommended initial and final crack length. The results show that the fatigue life due to autofrettage is more than nonautofrettage cylinder between Py1 and Py2 where, Py1 is the pressure required at the onset of yielding which occurs at the inner surface of the cylinder and Py2 is the sufficient pressure to bring the outer surface of the cylinder to yielding, i.e. the wall of cylinder becomes fully plastic.

scholarly journals Fatigue Test Results and Fatigue Life Estimation on Hard Steel and Aluminum Alloy under Random Loads

1975 ◽  
Vol 18 (122) ◽  
pp. 761-768
Author(s):  
Minoru KAWAMOTO ◽  
Hiroshi ISHIKAWA ◽  
Nobuo INOUE ◽  
Yoshio YOSHIDA
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Test Results ◽  
Life Estimation ◽  
Random Loads ◽  
Hard Steel ◽  
Fatigue Life Estimation

scholarly journals Research on the Influence of Non-Stationary and Non-Gaussian Random Excitation on Structural Response Kurtosis

2021 ◽  
Author(s):  
Xin Zeng ◽  
Yu Jiang ◽  
Wuyang Lei ◽  
Zhengwei Fan
Keyword(s):  
Fatigue Life ◽  
Dynamic Response ◽  
Damping Ratio ◽  
Excitation Frequency ◽  
Structural Response ◽  
Random Excitation ◽  
Frequency Bandwidth ◽  
Random Load ◽  
Vibration Fatigue ◽  
Non Gaussian

Abstract The stationary gaussian hypothesis is usually used to estimate the vibration fatigue life of structures. However, in actual engineering, the dynamic response of the structure usually exhibits non-stationary and non-gaussian, especially under harsh working condition or changing environment. The structural vibration fatigue life is closely related to the dynamic response characteristics, especially with respect to the structural response kurtosis used to characterize the non-Gaussian characteristics. In this paper, the influence of non-stationary and non-Gaussian random excitation on structural response kurtosis was studied by means of simulation and experiment. Firstly, by the means of simulating, the transmission law of excitation-response kurtosis was studied from three aspects, including system damping ratio, excitation frequency bandwidth, and excitation non-stationary characteristics. Then, the response kurtosis law was verified by the test results of cantilever vibration stress response. The results show that when the excitation is a stationary gaussian random load, the damping ratio and the excitation frequency bandwidth have no effect on the response kurtosis, and the response is approximately Gaussian distribution. When the excitation is stationary non-gaussian and non-stationary non-gaussian random load, if the damping ratio of the system is large, the response kurtosis is mainly affected by the damping ratio; If the damping ratio of the system is small, the frequency bandwidth and non-stationarity of the excitation have significant effects on the response kurtosis. The research results can provide support for predicting the vibration response and fatigue life of engineering structures under complex non-stationary non-gaussian random loads.

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