Statistic Analysis of Non-Gaussian Random Load

2021 ◽  
pp. 5-22
Author(s):  
Yu Jiang ◽  
Junyong Tao ◽  
Xun Chen
Keyword(s):  
Statistic Analysis ◽  
Random Load ◽  
Non Gaussian

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.

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 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.

Perbedaan Analisis Sefalometri Skeletal Sebelum dan Sesudah Perawatan Alat Myofunctional pada Pasien Maloklusi Dentoskeletal Kelas II Divisi I dalam Masa Pertumbuhan dengan Metode Steiner

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Nugroho Ahmad Riyadi
Keyword(s):  
Orthodontic Treatment ◽  
Class Ii ◽  
T Test ◽  
Analytic Study ◽  
Statistic Analysis ◽  
Twin Block ◽  
Normal Occlusion ◽  
Division 1 ◽  
Before And After ◽  
Class Ii Division 1

The aim of orthodontics treatment is normalization of teeth position in three planes, using various orthodontics appliance to reach the chepalometric standar and normal occlusion. Orthodontic treatment for dentoskeletal class II division 1 malocclusion in growing patients using myofunctional appliance may correct anteroposterior planes of mandibula. This study was a descriptive retrospective analytic study to look at the success of Orthodontic treatment for dentoskeletal class II division 1 in growing patients with myofunctional appliance using chepalometrics analysis Steiner value. The sample used in this study is chepalogram radiographic from patient with dentoskeletal class II division 1 malocclusion in growing patients before and after using myofunctional appliance in PPDGS orthodontics Clinic of Padjadjaran University. Statistic analysis were performed with pair t-test and Wilcoxon. Based on this study, it is concluded that orthodontic treatment with myofunctional appliance such as activator and twin block in growing patient with dentoskeletal class II division 1 malocclusion shows significant changes and compatibility with the normal criteria.

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