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基于采样云纹法的CFRP正交层合板材料的应变分布测量

王庆华,刘润芃,闫晓军   

  1. 北京航空航天大学
  • 收稿日期:2024-03-13 修回日期:2024-07-03 出版日期:2024-07-11 发布日期:2024-07-11
  • 通讯作者: 王庆华
  • 基金资助:
    国家自然科学基金

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

  • Received:2024-03-13 Revised:2024-07-03 Online:2024-07-11 Published:2024-07-11

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。本文建立了一种基于采样云纹法的测量CFRP正交层合板试样层间裂纹应变场的实验系统,该系统由三点弯曲试验加载装置、显微镜和工业相机以及贴有纳米压印光栅的CFRP试样组成。本文运用该系统对试样加载过程中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。本文开发的实验方法可以准确地测量CFRP层合板材料在裂纹萌生前的应变场,并有效地预测裂纹萌生的位置。

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

Abstract: 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. An experimental system for measuring interlaminar crack strain field of CFRP cross-ply laminate samples based on sampling moiré method is established. The system consists of a three-point bending test loading device, a microscope, an industrial camera and a CFRP sample with a nanoim-print grating. In this paper, the system is used to measure the strain field in the loading process of the specimen, and the strain con-centration degree before the specimen begins to bend to crack initiation is 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 the crack initiation, and with the increase of bending load, the strain concentration in the central region increases significantly, while the strain concentra-tion in the surrounding region does not change significantly. The experimental method developed in this paper can accurately meas-ure the strain field of CFRP laminates before crack initiation and predict the location of crack initiation effectively.

Key words: Sampling Moiré method, Carbon Fiber Reinforced Polymer, strain field measurement, crack initiation, Experimental mechanics

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