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 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 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.

scholarly journals Improved numerical model for fatigue cumulative damage of mechanical structure considering load sequence and interaction

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199530
Author(s):  
Bixiong Huang ◽  
Shuci Wang ◽  
Shuanglong Geng ◽  
Xintian Liu
Keyword(s):  
Fatigue Life ◽  
Theoretical Basis ◽  
Life Prediction ◽  
Damage Model ◽  
Cumulative Damage ◽  
Load Spectrum ◽  
Random Load ◽  
Mechanical Parts ◽  
Proposed Model ◽  
Load Sequence

To more accurately predict the fatigue life of components under the action of random loads, it is necessary to explore the influence of the interaction between the load sequence and the load on the life prediction. Based on the Manson-Halford method and Corten-Dolan model, this paper establishes a fatigue cumulative damage model that takes into account both the load order and the interaction between loads, and also takes into account the loads near the fatigue limit. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. Comparing the calculation results of the proposed model with the results of Palmgren Miner, Manson-Halford method, and Corten-Dolan model, it is found that the fatigue damage model established can reasonably predict the fatigue life of parts. Comparison and verification of examples further prove the accuracy and reliability of the proposed model.

Realization and Analysis of Bending Fatigue Strength Test for Gears under Random Loading

2011 ◽  
Vol 291-294 ◽  
pp. 1297-1302
Author(s):  
Jian Jun Hu ◽  
Hong Bin Xu ◽  
Shi Hua Zu ◽  
Xiao Wang Gao
Keyword(s):  
Fatigue Life ◽  
Gaussian Distribution ◽  
Testing Machine ◽  
Load Condition ◽  
Load Spectrum ◽  
Random Loading ◽  
Random Load ◽  
Bending Fatigue ◽  
Hydraulic Servo ◽  
Bending Fatigue Strength

For the bending fatigue under the random load condition, the Miner cumulative fatigue theory was analyzed qualitatively. Random amplitude fatigue load spectrum for experiments was compiled according to that gears work under the load with Gaussian distribution load spectrum. Gear bending fatigue was carried out by the method of group test under the conditions of random load on the electro-hydraulic servo testing machine. Then the P-S-N curve of bend fatigue was got under Gaussian distribution load spectrum with particular coefficient of variation. Experiments prove that fatigue life from the result of random luffing amplitude fatigue experiments is lower than that from constant amplitude fatigue experiments, in which the upper limit of fatigue loads is the mean of load spectrum. It will be not reliable to estimate the bending fatigue life of gears that in the actual service.

Probabilistic fatigue life prediction and reliability assessment of a high pressure turbine disc considering load variations

2017 ◽  
Vol 27 (10) ◽  
pp. 1569-1588 ◽  
Author(s):  
Shun-Peng Zhu ◽  
Qiang Liu ◽  
Qiang Lei ◽  
Qingyuan Wang
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Life Prediction ◽  
Reliability Assessment ◽  
Fatigue Life Prediction ◽  
Load Spectrum ◽  
High Pressure Turbine ◽  
Random Load ◽  
Load Variations ◽  
Turbine Disc

In the present work, a probabilistic framework for fatigue life prediction and reliability assessment of an engine high pressure turbine disc is proposed to incorporate the effects of load variations and mean stress, which provides a reference for engine structural design under a given target failure probability. Within this framework, a new probabilistic fatigue damage accumulation model under random loadings is elaborated based on a ductility exhaustion model, and probabilistic [Formula: see text] curves for the high pressure turbine disc under different flight missions are derived based on experimental data of turbine disc alloy GH4169. The influence of random load variations on fatigue reliability of the high pressure turbine disc has been investigated and quantified by combining the engine load spectrum with finite element analysis.

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 Random Load Fatigue Damage Accumulation in Mild Steel

1973 ◽  
Vol 187 (1) ◽  
pp. 285-293 ◽  
Author(s):  
B. C. Fisher ◽  
F. Sherratt
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Crack Detection ◽  
High Sensitivity ◽  
Optical Microscope ◽  
Random Loading ◽  
Random Load ◽  
Initiation Phase ◽  
Fatigue Damage Accumulation ◽  
Probability Density Distributions

Using high-sensitivity eddy-current crack detection, quantitative division of fatigue life into two stages has been achieved for a variety of random and constant amplitude loading conditions. The divisions adopted were: Stage A, microcrack initiation and propagation, and Stage B, macrocrack propagation. The results of specimen sectioning and optical microscope work show that this behaviour is physically compatible with the observations of Forsyth (1)‡. It is established under random loading that for a given specimen configuration, the proportion of time spent in stage A behaviour for a given fatigue life remains unaltered for changes in the waveform irregularity factor. This statement applies to two series of tests for loading waveforms of unaltered fundamental p.s.d. (power spectral density) shapes and Gaussian amplitude probability density distributions. It is suggested that the signal maximum peak/r.m.s. ratio is a significant factor in determining the proportion of life spent in crack initiation. Cumulative damage predictions are made using Miner's hypothesis on a basis of positive peak stresses to failure for stage A and stage B lives, and overall fatigue life. The results confirm that Miner seriously underestimates the damage contribution at low stresses on fatigue life as a whole, and also for the crack initiation phase of life.

Study on Fatigue Life of Pressure Vessels Based on Random Load

2012 ◽  
Vol 569 ◽  
pp. 400-404
Author(s):  
Guang Zhong Hu ◽  
Zhong Bin Liu ◽  
Liu Kang ◽  
Tao Quan Wang
Keyword(s):  
Fatigue Life ◽  
Design Theory ◽  
Pressure Fluctuations ◽  
Pressure Vessels ◽  
Stochastic Dynamic ◽  
Load Spectrum ◽  
Random Load ◽  
Life Analysis ◽  
Fatigue Life Analysis ◽  
Coupling Characteristics

The paper discusses the fatigue design theory of pressure vessels. For pressure vessel loads absorbed (pressure, temperature, earthquake, wind, snow, etc.) have significant stochastic dynamic characteristics and coupling characteristics, fatigue life analysis of pressure vessels based on random load history is proposed. Discusses in detail the random load spectrum rain flow counting process, the linear damage theory and fatigue life analysis. The new structure reactor of synthesis system fatigue life is calculated, the results show that the fatigue life and the design life of equipment vary widely, the need to improve pressure fluctuations of the synthesis of system.

Study on Fatigue Characteristic of Double Block Ballastless Track under Coupling Loads

2011 ◽  
Vol 422 ◽  
pp. 789-793 ◽  
Author(s):  
Zhi Ping Zeng ◽  
Xue Song Wang ◽  
Wen Rong Chen
Keyword(s):  
Fatigue Life ◽  
Design Parameters ◽  
Load Spectrum ◽  
Vertical Coupling ◽  
Ballastless Track ◽  
Steel Bar ◽  
Concrete Layer ◽  
Fatigue Damage Accumulation ◽  
Mechanical Models ◽  
Coupling Dynamics

Regarding double block ballastless track as research subject, three mechanical models were established, which include steel bar and concrete interaction mechanical model, spatial finite element static model of double block ballastless track, train-double block ballastless track vertical coupling dynamics model. According to concrete and steel bar stress time-dependant curves under axial even temperature and shrinkage load, temperature grads load and train load, fatigue load spectrum under coupling loads was obtained by using rain-flow counting method. Based on steel bar and concrete S-N curve, and Palmgren-Miner linear fatigue damage accumulation rule, track concrete layer fatigue life predicting model of double block ballastless track was established. Taking Changsha climatic condition for an example, the fatigue life of double block ballastless track is predicted, and the effects of design parameters to fatigue life are analyzed.

Fatigue Life Prediction under Variable Loading Based a Non-Linear Energy Model

2016 ◽  
Vol 22 ◽  
pp. 14-21
Author(s):  
Abdelkader Djebli ◽  
Mostefa Bendouba ◽  
Aid Abdelkarim
Keyword(s):  
Fatigue Life ◽  
Aluminium Alloy ◽  
Fatigue Damage ◽  
Damage Model ◽  
Experimental Results ◽  
Random Loading ◽  
Random Load ◽  
Complex Load ◽  
Proposed Model ◽  
Fatigue Damage Accumulation

A method of fatigue damage accumulation based upon application of energy parameters of the fatigue process is proposed in the paper. Using this model is simple, it has no parameter to be determined, it requires only the knowledge of the curve W–N (W: strain energy density N: number of cycles at failure) determined from the experimental Wöhler curve. To examine the performance of nonlinear models proposed in the estimation of fatigue damage and fatigue life of components under random loading, a batch of specimens made of 6082 T6 aluminium alloy has been studied and some of the results are reported in the present paper. The paper describes an algorithm and suggests a fatigue cumulative damage model, especially when random loading is considered. This work contains the results of uni-axial random load fatigue tests with different mean and amplitude values performed on 6082 T6 aluminium alloy specimens. The proposed model has been formulated to take into account the damage evolution at different load levels and it allows the effect of the loading sequence to be included by means of a recurrence formula derived for multilevel loading, considering complex load sequences. It is concluded that a ‘damaged stress interaction damage rule’ proposed here allows a better fatigue damage prediction than the widely used Palmgren–Miner rule, and a formula derived in random fatigue could be used to predict the fatigue damage and fatigue lifetime very easily. The results obtained by the model are compared with the experimental results and those calculated by the most fatigue damage model used in fatigue (Miner’s model). The comparison shows that the proposed model, presents a good estimation of the experimental results. Moreover, the error is minimized in comparison to the Miner’s model.

Sign in / Sign up

Export Citation Format

Share Document