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Structural Health Monitoring of CFRP Laminates : Development of 90-degree Crack Detection and Suppression System

CFRP 层压板的结构健康监测：90 度裂纹检测和抑制系统的开发

基本信息

批准号：
13450397
负责人：
TAKEDA Nobuo
金额：
$ 9.54万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13450397/
关键词：
carbon fiber reinforced plastics optical fiber FBG sensor 90-degree crack reflection -light spectrum crack detection crack suppression クラック発生抑制形状記憶合金

项目摘要

The purpose of the present study is to develop a structural health monitoring system to detect and suppress transverse cracks in a90-degree layer which generate at the early stage of loading.Transverse crack detection was made with a small-diameter (40 μm in coating diameter, 52 μm in coating diameter) Fiber Bragg Grating (FBG) sensor embedded in the CFRP lamina neighboring to the 90-degree layer. Transverse cracks generated in the gage section of the FBG sensor induce non-uniform strain distribution in the same section and change in the reflection spectrum of the sensor. This phenomenon can be used for the detection of transverse cracks. The experiments for the transverse crack detection were successfully conducted for cross-ply laminates as well as quasi-isotropic laminates. The experimental results were also reasonably explained by the theoretical analysis of the non-uniform strain distribution and the fiber optic theory.Transverse crack suppression was made with a 40-μn thick pre-strained shape memory alloy (SMA) foil embedded in the interlaminar region. When the pre-strained SMA is heated, the SMA shrinks and the recovery stress is generated, which retards the strain level of crack initiation and reduces the crack multiplication rate. The experiments for the transverse crack suppression were successfully conducted for cross-ply laminates at different temperatures. These experimental results were also reasonably explained by the theoretical analysis based on both the modified Brinson model for SMA constitutive equation and the shear-lag analysis. Then the optimum condition was determined for the SMA location, pre-strain level and applied temperature.Then, both detection and suppression systems were implemented in the same CFRP laminate to demonstrate the simultaneous damage detection and suppression system. The damage suppression system was successfully operated after the damage detection system detected the transverse cracks in the 90-degree ply.

本研究的目的是开发一种结构健康监测系统，以检测和抑制加载初期产生的90度层横向裂纹，采用小直径（涂层直径40 μm，涂层直径52 μm）光纤布拉格光栅（FBG）传感器嵌入邻近90度层的CFRP层中进行横向裂纹检测。在光纤光栅传感器的应变计截面上产生横向裂纹，引起应变在同一截面上的不均匀分布，并改变传感器的反射谱。这种现象可用于横向裂纹的检测。对正交铺设层合板和准各向同性层合板进行了横向裂纹检测实验。通过对非均匀应变分布的理论分析和光纤理论对实验结果进行了合理的解释，并在层间区域嵌入了40 μ m厚的预应变形状记忆合金（SMA）箔来抑制横向裂纹。当预应变SMA被加热时，SMA收缩并产生回复应力，这延缓了裂纹萌生的应变水平，降低了裂纹扩展速率。在不同温度下，对正交铺层层板进行了横向裂纹抑制实验。基于修正的Brinson模型的SMA本构方程和剪滞分析的理论分析也合理地解释了这些实验结果。通过对SMA位置、预应变水平和施加温度的优化，确定了SMA的最佳位置和施加温度，并在同一CFRP层合板上进行了损伤检测和抑制实验，验证了SMA损伤检测和抑制系统的可行性。在损伤检测系统检测到90 °铺层中的横向裂纹后，损伤抑制系统成功地运行。