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.

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 Experimental Design and Validation of an Accelerated Random Vibration Fatigue Testing Methodology

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Yu Jiang ◽  
Gun Jin Yun ◽  
Li Zhao ◽  
Junyong Tao
Keyword(s):  
Fatigue Life ◽  
Stress Responses ◽  
Life Prediction ◽  
Random Vibration ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Power Spectral ◽  
Vibration Fatigue ◽  
Non Gaussian

Novel accelerated random vibration fatigue test methodology and strategy are proposed, which can generate a design of the experimental test plan significantly reducing the test time and the sample size. Based on theoretical analysis and fatigue damage model, several groups of random vibration fatigue tests were designed and conducted with the aim of investigating effects of both Gaussian and non-Gaussian random excitation on the vibration fatigue. First, stress responses at a weak point of a notched specimen structure were measured under different base random excitations. According to the measured stress responses, the structural fatigue lives corresponding to the different vibrational excitations were predicted by using the WAFO simulation technique. Second, a couple of destructive vibration fatigue tests were carried out to validate the accuracy of the WAFO fatigue life prediction method. After applying the proposed experimental and numerical simulation methods, various factors that affect the vibration fatigue life of structures were systematically studied, including root mean squares of acceleration, power spectral density, power spectral bandwidth, and kurtosis. The feasibility of WAFO for non-Gaussian vibration fatigue life prediction and the use of non-Gaussian vibration excitation for accelerated fatigue testing were experimentally verified.

Design and control performance of a frictional tuned mass damper with bearing–shaft assemblies

2019 ◽  
Vol 25 (12) ◽  
pp. 1812-1822 ◽  
Author(s):  
Jinwei Jiang ◽  
Siu Chun Michael Ho ◽  
Nathanael J Markle ◽  
Ning Wang ◽  
Gangbing Song
Keyword(s):  
Damping Ratio ◽  
Excitation Frequency ◽  
Structural Response ◽  
Tuned Mass Damper ◽  
Resonant Peak ◽  
Equivalent Viscous Damping ◽  
Optimal Damping ◽  
Mass Damper ◽  
And Control ◽  
Equivalent Viscous Damping Ratio

This paper explores the feasibility of leveraging the damping generated by the friction between movable flange-mounted ball bearings and a stationary shaft. This bearing–shaft assembly is integrated with a tuned mass damper to form a frictional tuned mass damper (FTMD). The friction coefficient and the equivalent viscous damping ratio of the proposed FTMD were experimentally obtained based on different cases of glass, steel, and aluminum slide shafts. The proposed FTMD was modeled and simulated numerically to study its ability to suppress vibrations on a single degree of freedom structure. Furthermore, a parallel experimental validation of the FTMD was also executed to verify simulation results. Results from both experiments and simulations demonstrated that the proposed FTMD device was able to significantly improve the damping ratio of the primary structure from 0.35% to 5.326% during free vibration, and also to suppress around 90% of uncontrolled structural response at a tuned frequency. In particular, the frequency responses, among the tested shaft materials, suggested that the selected steel slide shaft practically provided a near-optimal damping coefficient, thus the proposed FTMD was able to considerably reduce structural resonant peak amplitudes over the tested excitation frequency domain.

scholarly journals A New Method to Calculate Additional Damping Ratio considering the Effect of Excitation Frequency

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Weizhi Xu ◽  
Dongsheng Du ◽  
Shuguang Wang ◽  
Weiwei Li
Keyword(s):  
Dynamic Response ◽  
Ground Motion ◽  
Calculation Method ◽  
Response Spectrum ◽  
Damping Ratio ◽  
Excitation Frequency ◽  
Structural Dynamic ◽  
Important Indicator ◽  
Simplified Calculation ◽  
Simplified Calculation Method

The additional damping ratio (ADR) is an important indicator for evaluating the damping effect of structures with energy-dissipation devices. Most existing methods for determining the ADR require an analysis of the structural dynamic response and complex iterative calculations. An innovative simplified calculation method for determining the ADR of a structure supplemented by nonlinear viscous dampers is proposed. This method does not require the dynamic response of the structure to be calculated and only requires the structural characteristics, excitation frequency, and damper parameters. In this study, several typical calculation methods for the ADR were analysed. Then, a calculation formula for the ADR was derived with consideration of harmonic excitation under the condition where the excitation frequency is equal to the structural natural frequency, without calculation of the structural dynamic response or an iterative process. The effect of the excitation frequency on the calculated value of the ADR with different damping exponents was studied. Accordingly, the response spectrum average period (RSAP) was considered as the excitation period of ground motion to evaluate the excitation frequency, and a simplified calculation method for the ADR considering the effect of the excitation frequency characterised by the RSAP of the ground motion was established. Finally, the accuracy and effectiveness of the proposed method were verified by comparison with ADRs calculated using other methods.

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 The Case Study of Pseudoexcitation Method Combining Self-Adaptive Gauss Integration in Random Vibration Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Ning Chen ◽  
Siyu Zhu ◽  
Yongle Li
Keyword(s):  
Vibration Analysis ◽  
Random Vibration ◽  
Critical Frequency ◽  
Damping Ratio ◽  
Structural Response ◽  
Coupled System ◽  
Random Excitation ◽  
Wide Frequency Range ◽  
Random Vibration Analysis ◽  
Self Adaptive

The pseudoexcitation method (PEM) can improve efficiency of random vibration analysis. However, for large-sized structures with wide frequency range of response, the workload of calculation is heavy if conventional integration methods, such as trapezoidal integration, are used to combine with the PEM to calculate structural response. In such case, self-adaptive technology is induced to combine with the PEM to form an efficient method for solving random vibration. During calculation, this method can realize the adaptability of random excitation to actual structural response, identify automatically critical frequency intervals of random excitation, and process intelligently the identified critical frequency intervals and noncritical frequency intervals. Based on the identified frequency intervals, Gauss integration is carried out to obtain response results with random characteristics. The computational efficiency and accuracy of PEM-SGI are verified by wind-induced performance of the slender bridge tower. Finally, the influence of damping ratio of the bridge structure and train marshalling on vehicle-bridge coupled system is investigated to further verify the application of the proposed method. Results show that the efficiency of solving random vibration can be improved by the present method.

scholarly journals Dynamic Response of Asymmetric and Nonlinear Packaging System under Random Excitation

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Song-Ping Yang ◽  
Zhi-Wei Wang
Keyword(s):  
Dynamic Response ◽  
Numerical Solutions ◽  
Random Excitation ◽  
Probability Density Functions ◽  
Density Functions ◽  
Nonlinear Stiffness ◽  
Damage Evaluation ◽  
Characteristic Parameters ◽  
Packaging System ◽  
Non Gaussian

This paper focuses on the dynamic response of three asymmetric and nonlinear packaging systems (ANPSs) of practical transport package under random excitation. Next to presenting the displacement probability density functions (PDFs) of ANPSs derived through FPK equations, the influences of the excitation grades and the characteristic parameters (such as the damping, the nonlinear stiffness, and the strain) of packaging cushion materials on the response are discussed in detail. Then, the generalized PDFs of the response peaks are defined and examined by three common distributions. The investigation shows that “inverse excitation cushion factors” (IECFs) have a significance on effecting the displacement PDFs approaching different distributions. Most PDFs of the unilateral response peaks approach Rayleigh distributions and present non-Gaussian characters. The present methods are verified through the validation numerical solutions. Furthermore, the application of the scheme for fatigue damage evaluation of the transport package is carried out.

scholarly journals Numerical Investigation of the Dynamic Response of Symmetric Laminated Composite Beams to Harmonic Excitations

2009 ◽  
Vol 18 (5) ◽  
pp. 096369350901800 ◽  
Author(s):  
Zeki Kıral
Keyword(s):  
Dynamic Response ◽  
Frequency Response ◽  
Flexural Rigidity ◽  
Plate Theory ◽  
Damping Ratio ◽  
Excitation Frequency ◽  
Laminated Composite ◽  
Harmonic Excitation ◽  
Numerical Results ◽  
Harmonic Response

The aim of this study is to investigate the dynamic response of a laminated composite beam subjected to a harmonic excitation by a numerical time integration method known as Newmark method. The finite element method based on the classical laminated plate theory is used in order to obtain structural stiffness. The structural damping is modelled as proportional damping which is referred to as Rayleigh damping and two different damping ratios are used. The effect of damping on the frequency response of the beam is investigated for a broad range of excitation frequency. The effect of excitation point on the harmonic response is also considered. Four different lay-up configurations namely [0]2s, [0/90]s, [45/-45]s and [90]2s are considered in order to show the effect of the stacking sequence on the frequency response of the beam. The numerical results presented in this study show that, the magnitude of the harmonic response of the beam reduces considerably as the damping ratio increases and [90]2s lay-up produces largest dynamic response due to the reducing flexural rigidity. Numerical results also show that the location and frequency of the harmonic excitation has important role on the dynamic response of the beam.

Bending fatigue of single-wall and double-wall corrugated paperboards under sinusoidal and random loads

2021 ◽  
pp. 109963622110204
Author(s):  
Zhi-Wei Wang ◽  
Yang-Zhou Lai ◽  
Li-Jun Wang
Keyword(s):  
Energy Dissipation ◽  
Fatigue Failure ◽  
Fatigue Tests ◽  
Stiffness Degradation ◽  
Random Load ◽  
Bending Fatigue ◽  
Random Loads ◽  
Vibration Fatigue ◽  
Sinusoidal Load ◽  
Double Wall

The bending fatigue tests of single-wall and double-wall corrugated paperboards were conducted to obtain the εrms– N curves under sinusoidal and random loads in this paper. The εrms– N equation of corrugated paperboard can be described by modified Coffin–Manson model considering the effect of mean stress. Four independent fatigue parameters are obtained for single-wall and double-wall corrugated paperboards. The εrms– N curve under random load moves left and rotates clockwise compared with that under sinusoidal load. The fatigue life under random load is much less than that under sinusoidal load, and the fatigue design of corrugated box should be based on the fatigue result under random load. The stiffness degradation and energy dissipation of double-wall corrugated paperboard before approaching fatigue failure are very different from that of single-wall one. For double-wall corrugated paperboard, two turning points occur in the stiffness degradation, and fluctuation occurs in the energy dissipation. Different from metal materials, the bending fatigue failure of corrugated paperboard is a process of wrinkle forming, spreading, and folding. The results obtained have practical values for the design of vibration fatigue of corrugated box.

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