3D damage characterisation and the role of voids in the fatigue of wind turbine blade materials
3D damage characterisation and the role of voids in the fatigue of wind turbine blade materials
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DOI：
10.1016/j.compscitech.2011.11.023
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发表时间：
2012-01-18
影响因子：
9.1
通讯作者：
Spearing, S. M.
中科院分区：
文献类型：
--
作者：
Lambert, J.;Chambers, A. R.;Spearing, S. M.
采用计算机断层扫描（CT）技术对风力涡轮机叶片用玻璃纤维增强复合材料（GFRP）的疲劳机理进行了研究。在机械测试之前，对制造的[+45/-45/0]（3，s）玻璃/环氧树脂样本进行CT扫描，以提供其内部微观结构（包括空隙）的三维图像。对空隙进行分割和提取，并对个体特征和体积分布进行量化。然后在R =标称拉伸失效应力的-1%至40%的单轴载荷下对试样进行疲劳试验。为了与初始空隙分析相关并建立失效模式，进行了一些失效试验。其他测试在不同的寿命分数停止，并使用CT检查以确定关键的损伤机制。这些扫描显示在表面层中的横向基体开裂，主要发生在自由边缘。然后，这些自由边缘裂纹似乎促进了45/-45度界面处的边缘分层。从亚临界表面层损坏到临界内层损坏的扩展被确定为-45/0度分层或0度纤维束失效，从而允许裂纹扩展到样本本体中。最终失效发生在压缩中，其特征在于所有45/-45度层片之间的完全分层。还对试验前的CT扫描进行了定量空隙分析，并与试样的疲劳寿命进行了比较。据作者所知，这项分析是同类分析中的第一次，测量并绘制了每个样本标距长度内的大约10，000个空隙。整体空隙测量参数和分布与疲劳寿命没有相关性。一个当地的水平的调查显示，最大的空隙和疲劳寿命之间的显着的相关性，在该区域的层压板与裂纹扩展从亚临界到临界损伤。(C)2011爱思唯尔有限公司保留所有权利。
The fatigue mechanisms of Glass Fibre Reinforced Polymer (GFRP) used in wind turbine blades were examined using computed tomography (CT). Prior to mechanical testing, as-manufactured [+45/-45/0](3,s) glass/epoxy specimens were CT scanned to provide 3-dimensional images of their internal microstructure, including voids. Voids were segmented and extracted, and individual characteristics and volumetric distributions were quantified. The coupons were then fatigue tested in uniaxial loading at R = -1% to 40% of the nominal tensile failure stress. Some tests were conducted to failure for correlation with the initial void analysis and to establish failure modes. Other tests were stopped at various life fractions and examined using CT to identify key damage mechanisms. These scans revealed transverse matrix cracking in the surface layer, occurring predominantly at free edges. These free-edge cracks then appeared to facilitate edge delamination at the 45/-45 degrees interface. Propagation from sub-critical, surface ply damage to critical, inner ply damage was identified with either a -45/0 degrees delamination, or a 0 degrees fibre tow failure allowing a crack to propagate into the specimen bulk. Final failure occurred in compression and was characterised by total delamination between all the 45/-45 degrees plies. A quantitative void analysis, taken from the pre-test CT scans, was also performed and compared against the specimens' fatigue lives. This analysis, to the authors' knowledge the first of its kind, measured and plotted approximately 10,000 voids within the gauge length of each specimen. The global void measurement parameters and distributions showed no correlation with fatigue life. A local ply-level investigation revealed a significant correlation between the largest void and fatigue life in the region of the laminate associated with the crack propagation from sub-critical to critical damage. (C) 2011 Elsevier Ltd. All rights reserved.