基于采样云纹法的CFRP正交层合板材料应变分布测量  

Measurement of strain distribution in CFRP cross-ply laminate material based on sampling Moiré method

作　　者：王庆华 刘润芃 闫晓军[1] Qinghua WANG;Runpeng LIU;Xiaojun YAN(School of Energy and Power Engineering,Beihang University,Beijing 100191,China)

机构地区：[1]北京航空航天大学能源与动力工程学院,北京100191

出　　处：《航空学报》2024年第24期256-266,共11页Acta Aeronautica et Astronautica Sinica

基　　金：国家自然科学基金(12372176);国家科技重大专项(J2019-Ⅳ-0007-0075)。

摘　　要：近年来,碳纤维增强复合材料(CFRP)在航空工业中的发展令人瞩目,对其断裂过程进行定量评估并预测损伤成为了研究的关键。基于采样云纹法,建立了一种研究CFRP正交层合板试样层间应变场演化规律的实验系统;该系统由三点弯曲实验加载装置、显微镜和工业相机以及贴有纳米压印光栅的CFRP试样组成。运用该系统对试样加载过程中微尺度下的应变场进行全场测量,并对试样开始弯曲至裂纹萌生前的应变集中程度进行了定量评估。结果表明:CFRP正交层合板材料层间裂纹的萌生与应变集中有直接联系,裂纹在萌生前会伴随明显的应变集中;裂纹中心相较于裂纹周围区域在起裂前有更明显的应变集中,且随着弯曲载荷增大,中心区域的应变集中程度明显增加,周围区域的应变集中程度则无明显变化。当CFRP表面图像的设定应变为0.1%时,所用实验方法应变测量的均方根误差在5×10^(-5)以内,可以准确分析CFRP层合板材料在裂纹萌生前的应变场演化规律,并有效地预测裂纹萌生的位置。In recent years,the development of Carbon Fiber Reinforced Polymer(CFRP)in the aviation industry has attracted much attention.Quantitative evaluation of its fracture process and damage prediction has become the key of the research.This paper established an experimental system based on the sampling Moirémethod to study the evolution of interlayer strain field of a CFRP cross-ply laminate sample.The system consists of a three-point bending device,a microscope,an industrial camera and a CFRP sample with a nanoimprint grating.Using this system,a full-field measurement of the microscale strain field in the loading process of the sample,and the strain concentration level before crack occurrence was quantitatively evaluated.The results show that the initiation of interlayer cracks in CFRP is directly related to strain concentration,and obvious strain concentration occurs before crack initiation.Compared with the region around the crack,the strain concentration in the crack center is more obvious before crack initiation.With the increase of bending load,the strain concentration in the central region increases significantly,while the strain concentration in the surrounding region does not change distinctly.In the experimental method used,when the set strain of CFRP surface image is 0.1%,the root mean square error of strain measurement is less than 5×10^(-5).This allows for accurate analysis of the strain field evolution of CFRP laminates before crack initiation and effectively predicts the location of crack initiation.

关 键 词：采样云纹法 CFRP复合材料 应变场测量 裂纹萌生 实验力学 微尺度测量 

分 类 号：V254[一般工业技术—材料科学与工程]