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Multi-Excitation fatigue testing for Large Full-Scale Wind Turbine Blade

Journal of Donghua University(English Edition) 2020年第5期37卷 417-424页

作者： PAN Zujin WU Jianzhong ZHANG Zhenguo School of Mechanical Engineering Tongji UniversityShanghai 200092China Shanghai Electric Wind Power Co. Ltd.Shanghai 200235China

In order to solve the problem of insufficient exciting force of equipment for large full-scale wind turbine blade fatigue testing,the influence of gravity on the performance of excitation equipment and fatigue damage evaluation of the different positions of wind turbine blades are *** the multi-excitation loading in the horizontal direction,the actuator force of the excitation equipment does not need to overcome the gravity of the dynamic mass,which directly outputs the exciting force of the system *** excitation efficiency of the equipment is 77%higher than that of the vertical *** gravity moment of the horizontal loading mode is perpendicular to the loading *** is,the mean load in the flapwise direction is *** weight of excitation equipment could replace the tuning mass on the condition that the self-weight of equipment is reduced by the multi-excitation mode,which helps the excitation equipment play the comprehensive function of excitation equipment and tuning *** the same time,the gravity moment in the edgewise direction will be decreased by 17.0%22.5%under the multi-excitation horizontal loading *** the vertical loading mode,the gravity moment is the mean load,which only increases fatigue damage accumulation by 15.6%.By comparing the role of gravity in the excitation equipment and fatigue damage evaluation,the multi-excitation horizontal loading mode has more advantage to performance the exciting force than the contribution of gravity to the fatigue damage accumulation in the vertical loading *** the fatigue testing of multi-excitation horizontal loading,the potential of excitation equipment is explored,and the problem of insufficient exciting force in large full-scale wind turbine blade fatigue testing will be solved.

关键词： wind turbine blade fatigue testing multi-excitation exciting force equivalent fatigue damage accumulation

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Acoustic Emission Properties of Concrete Slab During fatigue testing with a Running-Wheel Load

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Journal of Civil Engineering and Architecture 2017年第3期11卷 213-221页

作者： Mitsuharu Shiwa Zhengwang Li Takuya Maeshima Yasuhiro Koda Yasushi Tanaka National Institute for Materials Science Tsukuba Ibaraki 305-0047 Japan Nippon Physical Acoustics Ltd. Tokyo 150-0011 Japan Department of Civil Engineering College of Engineering Nihon University Koriyama Fukushima 963-1165 Japan Institute of Industrial Science The University of Tokyo Tokyo 153-8505 Japan

AE （acoustic emission） signals from concrete slab during fatigue testing with a running-wheel load were evaluated. The signals were recorded by remote sensors connected to a computer network. The sensing equipment consisted of 60 kHz resonant-type AE sensors mounted on a reinforcing steel bar as a waveguide, together with a 16-channel sensor highway AE system. Because the detected AE signals included periodic mechanical noise from the motion of the wheel, these noises were eliminated by means of signal processing. The AE waveguide measurement over a length of 3 m detected fractures as vertical and horizontal cracks in the RC （reinforced concrete） slab. Those cracks were analyzed by correlating AE parameters with macroscopic distortions and the numbers of fatigue cycles. In the AE events and AE energy, two types of AE phenomena, active region and inactive region, were observed during fatigue testing. The vertical cracks were characterized by an AE amplitude of 58 dB, a peak frequency of 30 kHz, and a ratio of the rise time to the maximum amplitude value （RA） of 100. The horizontal cracks were characterized by an AE amplitude of 85 dB, a peak frequency of 60 kHz, and an RA value of 10.

关键词： Acoustic emission concrete slab waveguide fatigue testing running-wheel load.

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Improvement of titanium alloy TA19 fatigue life by submerged abrasive waterjet peening:Correlation of its process parameters with surface integrity and fatigue performance

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Chinese Journal of Aeronautics 2024年第1期37卷 377-390页

作者： Gongyu WANG Shulei YAO Yuxin CHI Chengcheng ZHANG Ning WANG Yalong CHEN Rongsheng LU Zhuang LI Xiancheng ZHANG Key Laboratory of Pressure Systems and Safety Ministry of EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China AECC Commercial Aircraft Engine Co.LTD Shanghai Engineering Research Center for Commercial Aircraft EngineShanghai 201108China

Submerged abrasive waterjet peening(SAWJP)is an effective anti-fatigue manufacturing technology that is widely used to strengthen aeroengine *** study investigated the correlation of SAWJP process parameters on surface integrity and fatigue life of titanium alloy *** with different water pressures and standoff distances(SoDs)was conducted on the TA19 *** surface integrity of the specimens before and after SAWJP with different process parameters was experimentally studied,including microstructure,surface roughness,microhardness,and compressive residual stress(CRS).Finally,fatigue tests of the specimens before and after SAWJP treatment with different process parameters were carried out at room *** results highlighted that the fatigue life of the TA19 specimen can be increased by 5.46,5.98,and 6.28 times under relatively optimal process parameters,which is mainly due to the improved surface integrity of the specimen after SAWJP ***,the fatigue life of specimens treated with improper process parameters is decreased by 0.55 to 0.69 times owing to the terrible surface roughness caused by the material *** work verifies that SAWJP can effectively improve the surface integrity and fatigue life of workpieces,and reveals the relationship between process parameters,surface integrity,and fatigue life,which provides support for the promotion of SAWJP in the manufacturing fields.

关键词： fatigue testing Process parameters Submerged abrasive waterjet peening Surface integrity Surface treatment Titanium alloy TA19

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DELAMINATION FORMATION AND DELAMINATION PROPAGATION OF COMPOSITE LAMINATES UNDER COMPRESSIVE fatigue LOADING

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Chinese Journal of Aeronautics 2000年第1期13卷 8-13页

作者：熊峻江 Research Center of Solid Mechanics Beijing Univ. Aeronauatics A. Beijing 100083 China

fatigue tests of the smooth composite laminates and the notched composite laminates under compressive cyclic loading have been carried out. The damage mechanism is discussed and analyzed. Damage evolution is monitored using stiffness decay. From these tests, it is found that the initial delamination occurs at the free boundary of smooth specimens, or the notch boundary of notched specimens, subjected to the compression-compression cyclic load. A point of view in relation to two-phases of compression fatigue delamination of composites is proposed, namely, compression-compression delamination consists of the delamination formation phase and the delamination propagation, and there is a 'damage transition point' to separate this two-phases. Furthermore, an empirical modulus degradation formula and its parameters fitting method are presented. According to the test data handling results, it is shown that this formula is univocal and can fit the test data conveniently. In addition, two kinds of new anti-buckling devices are designed for these tests. At last, the E-N curves, the D-N curves and the S-N curve of the smooth carbon fiber reinforced composite laminates of T300/648C are determined to predict the fatigue life of the notched composite laminate. And the E-N curve of the notched specimens at the given load ratio R = 10 and minimum load Pmin = -0.45 kN is also measured to verify the estimated result of fatigue life.

关键词： Carbon fiber reinforced plastics Composite micromechanics Compressive strength Crack propagation Cyclic loads Delamination Elastic moduli fatigue testing Laminated composites Stiffness

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SHORT fatigue CRACK PARAMETER BASED ON THE TOTAL CRACK AREA

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Acta Metallurgica Sinica(English Letters) 2001年第4期14卷 235-240页

作者： Z.X. Wu and X. C. Wu Engineering College, Yangzhou University, Yangzhou 225009, China Eng. Coll. Yangzhou Univ. Yangzhou 225009 China

The progressive fatigue damage of a material is closely related to the whole population of cracks on its surface. In order to understand which parameter is a more useful indicator of fatigue damage, rotatory bending fatigue tests were carried out using smooth specimens of medium-carbon steel. The behavior of short crack propagation during fatigue was examined and a new parameter total crack area was suggested. The aim of this paper is to extend the research on fatigue damage in the already studied steel and to study how these damage parameters are correlated with the process of fatigue damage in order to evaluate the effectiveness of damage detection methods.

关键词： Bending strength Crack initiation Crack propagation fatigue testing Parameter estimation

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A NOVEL PARAMETER FOR EVALUATING THE fatigue CRACK GROWTH RATE IN CARBON STEELS

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Acta Metallurgica Sinica(English Letters) 2001年第4期14卷 271-279页

作者： X.S. Wang1), S.Q. Zhn1), N. Kawagoishi2) and H. Nisitani3) 1) Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China 2) Faculty of Engineering, Kagoshima University, Kagoshima, 890-0065, Japan Dept. of Eng. Mech. Tsinghua Univ. Beijing 100084 China

A novel parameter is suggested for evaluating the fatigue crack growth rate in carbon steels. fatigue crack propagation tests of an annealed 0.42% carbon steel were carried out under different conditions to investigate the relationship between this dominating parameter and the crack opening displacement (COD). A new equation of fatigue crack growth rate is formulated in terms of the suggested parameter. The physical meanings of the material parameters in this equation are explored experimentally. Considering the relation of crack growth and deformation properties, a simple and applicable method is proposed to evaluate the fatigue crack growth rate. It is also observed that the material parameters in the fatigue crack growth rate equation of carbon steels are related linearly to the material strength. The results are in a good agreement with experimental results.

关键词： Crack propagation Evaluation fatigue testing Parameter estimation

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Seawater Corrosion fatigue of Welded Joints Under Random Variable Amplitude Loading

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China Ocean Engineering 1993年第2期8卷 139-146页

作者： Xue, Yinian Xu, Jilin Li, Yanping Li, He Chinese Acad of Sciences Beijing China

Offshore platforms are always subjected to wave action which is random variable amplitude cyclic loading. In order to simulate the stressing condition at the 'hot spot' of the tubular joints and the marine environment, random variable amplitude fatigue tests have been carried out on welded plate joints in sea water. The tests have been conducted under the conditions of loading frequency of 0.2 Hz/, stress ratio of -1, seawater temperature of about 20°C and cathodic protection with the potential about -850 mV, SCE. The test results have been compared with the seawater corrosion fatigue life under constant amplitude loading. Miner's linear cumulative damage summation rule has been used to predict the corrosion fatigue life under variable amplitude loading. The predicted life is in good agreement with the test data.

关键词： Cathodic protection Corrosion fatigue Failure (mechanical) fatigue testing Joints (structural components) Offshore structures Production platforms Seawater Stresses Structural loads Water waves Welds

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fatigue Test of Homemade Z Direction Steel Welded T Tubular Joints

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China Ocean Engineering 1993年第2期8卷 217-224页

作者： Gao, Renliang Huang, Chengkui Yang, Guoxian Dalian Univ of Technology Dalian China

This paper introduces the process and result of fatigue test of steel (Z direction steel) welded T tubular joints used in offshore engineering. Detailed measurement of stress concentration factor, stress distribution, fatigue life and crack development has been performed. Through analysis, an empirical formula of stress concentration factor for T tubular joints, fatigue S-N curve and crack propagation rule are obtained.

关键词： Crack propagation fatigue of materials fatigue testing Ocean engineering Production platforms Stress analysis Stresses Welded steel structures Welds

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STATIC AND fatigue BEHAVIOR OF IMPACTED AS4/PEEK THERMOPLASTIC COMPOSITES UNDER COMPRESSION LOAD

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Chinese Journal of Aeronautics 2000年第1期13卷 14-18页

作者：沈真陈普会刘俊石 Aircraft Strength Research Institute CAE Xi'an 710065 China

Static and fatigue tests under compression load were made on impacted AS4/PEEK and T300/913C graphite/epoxy with [45/90/-45/0]5S stacking sequence. The comparison of the damage tolerance assessment for thermosetting and thermoplastic composites shows that thermoplastics are more damage tolerant under compression. Impacted thermoplastic composites have excellent compression-compression fatigue behavior. The damage growth life is only a few percent of their total fatigue life and no regular damage growth can be found. Some design principles for thermosetting composite structures may still be used.

关键词： Compressive strength Crack propagation Failure (mechanical) fatigue testing Graphite fiber reinforced plastics Impact resistance Polyether ether ketones Thermoplastics

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Effect of Interference Fits on the fatigue Lives of Bolted Composite Joints

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Journal of Shanghai Jiaotong university(Science) 2016年第6期21卷 648-654页

作者：吕新颖赵剑胡利汪海 School of Aeronautics and Astronautics Shanghai Jiaotong University Shanghai 200240 China Chengdu Aircraft Design and Research Institute Chengdu 610000 China

The effect of interference fits on the fatigue lives of bolted composite joints is investigated by conducting mechanical *** and fatigue tests are carried out on specimens made of carbon-bismaleimide composites joined together as double-lap single-bolt *** bolts having interference fits ranging of 0(neat fit),0.5%,0.75% and 1% are *** results demonstrate the relationship between fatigue life and different values of interference *** the fatigue tests,non-destructive evaluation(NDE) and scanning electron microscope(SEM) are used to observe the damage of the surrender and surface of the *** test results show that the interference fitted specimens have improved fatigue life compared to the neat fitted *** NDE and SEM results reveal that the damage degree of interference fitted specimen is weaker than that for the neat fitted one.

关键词： composite joints mechanical testing fatigue testing fatigue life non-destructive testing

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