风电叶片在疲劳试验过程中的声发射监测研究

发布时间：2018-06-04 22:23

本文选题：声发射 + 风电叶片　；参考：《兰州理工大学》2017年硕士论文

【摘要】：风能作为一种清洁的可再生能源,其开发日益受到人们重视,它将会成为未来人类社会赖以生存所必需的主要能源资源之一,风电行业具有广阔而美好的开发前景。然而风电叶片的安全保障问题是影响发电效率的一个重要因素之一,特别风电叶片长期在恶劣的自然环境下运行更容易出现事故。叶片一旦出现严重故障,很难做修复工作,而且大大降低了风电机组的正常工作效率,也会造成巨大的的经济损失。因此,风电叶片疲劳试验过程中的结构健康状态的监测对风电机组的安全运行起着非常重要的作用。声发射(Acoustic Emission)检测技术具有被动式和时效性检测特点,广泛应用于大型构件的结构健康监测,而风电叶片体积庞大且结构形式复杂,利用声发射技术监测风电叶片的结构健康状态对疲劳试验的进行起着非常重要的作用。本文在详细了解风电叶片常见的质量问题和声发射技术在国内外发展现状的基础上,基于声发射技术对风电叶片疲劳试验进行了全程结构健康检测并对复合材料的拉伸加载进行了声发射特性分析。主要研究了风电叶片在疲劳损伤的声发射特性以及通过声发射技术分析复合材料损伤演化机理。该试验的主要内容包括声发射信号在风电叶片复合材料中的衰减研究,多轴向复合材料力学性能的比较分析和有预断纤维与无预断纤维的声发射特性比较分析,以及全尺寸风电叶片在疲劳试验过程中的声发射应用研究。实验结果表明,声发射信号在风电叶片传播过程中横向比纵向衰减快而大,而在叶片纵向和横向传播过程中传播距离与信号幅度衰减速度关系一致,即随着信号在叶片上传播的距离越大幅度衰减就越快;风电叶片复合材料有预断纤维试件的拉伸载荷和拉伸模量均比无预断纤维试件的低,有预断纤维试件拉伸过程中的声发射信号能量主要集中在高频率段内,而无预断纤维信号能量主要集中在低频率段内,含预断纤维试件在拉伸过程中的声发射信号均表现为突发型信号;定位图趋势分析是一种简单的空间滤波技术,能够减少试验环境的干扰,并且通过能量、RMS等相关参数的趋势分析以及相互验证,能够很好地得到损伤的起始时间和状态。疲劳振动不同阶段AE信号在相同频段内的能量比例不同,损伤扩展严重,信号在低频段能量比例越小,高频段所占能量比例越大,以此可以表征损伤的演化程度。
[Abstract]:As a kind of clean renewable energy, wind energy development has been paid more and more attention. It will become one of the main energy resources necessary for the survival of human society in the future. Wind power industry has a broad and bright development prospects. However, the safety and security of wind turbine blade is one of the important factors that affect the efficiency of power generation, especially the wind turbine blade is more prone to accidents under the adverse natural environment for a long time. Once the blade has serious failure, it is very difficult to do repair work, and greatly reduces the normal working efficiency of wind turbine, and will cause huge economic losses. Therefore, the monitoring of structural health in wind turbine blade fatigue test plays an important role in the safe operation of wind turbine. Acoustic emission (AE) detection technology has been widely used in structural health monitoring of large components with the characteristics of passive and time-dependent detection, while the wind power blade is large in volume and complex in structure form. Using acoustic emission technology to monitor the structural health of wind turbine blades plays an important role in fatigue test. On the basis of detailed understanding of the common quality problems and acoustic emission technology of wind turbine blades at home and abroad, Based on acoustic emission (AE) technology, the fatigue test of wind turbine blade was carried out and the structural health of the composite was measured. The acoustic emission characteristics of composite materials under tensile loading were analyzed. The acoustic emission characteristics of wind turbine blades under fatigue damage and the damage evolution mechanism of composite materials were studied by acoustic emission technique. The main contents of the experiment include the attenuation of acoustic emission signals in wind turbine blade composites, the comparative analysis of mechanical properties of multiaxial composites and the comparative analysis of acoustic emission characteristics between pretreated and non-preconditioned fibers. And the acoustic emission application of full scale wind turbine blade in fatigue test. The experimental results show that the transverse attenuation of acoustic emission signal is faster and greater than that of longitudinal propagation in wind turbine blade, and the relationship between the propagation distance and the amplitude attenuation velocity of the signal is consistent during the longitudinal and transverse propagation of the blade. That is, the larger the distance of signal propagation on the blade, the faster the attenuation, the lower the tensile load and modulus of the wind turbine composite material with prebreak fiber, The acoustic emission (AE) signal energy of the specimen with precut fiber is mainly concentrated in the high frequency range, while the signal energy of the non-precut fiber is mainly concentrated in the low frequency region. The acoustic emission signals of the specimens with prebroken fibers are all sudden signals during the tensile process, and the orientation map trend analysis is a simple spatial filtering technique, which can reduce the interference of the test environment. Through the trend analysis and mutual verification of energy and RMS, the onset time and state of the damage can be obtained well. At different stages of fatigue vibration, the energy ratio of AE signal in the same frequency band is different, and the damage propagation is serious. The smaller the energy ratio of the signal in the low frequency band, the larger the energy ratio in the high frequency band, which can be used to characterize the degree of damage evolution.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM315

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