• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2025, Vol. 61 ›› Issue (12): 60-72.doi: 10.3901/JME.2025.12.060

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Experiment and Numerical Calculation Study on Damage Behaviors of Notched C/C Composites

LI Weiqi1, QI Lehua1, CHAO Xujiang1, GE Jian1, TIAN Wenlong1, LI Hejun2   

  1. 1. School of Mechatronic Engineering, Northwestern Polytechnical University, Xi'an 710072;
    2. Carbon/Carbon Composites Research Center, Northwestern Polytechnical University, Xi'an 710072
  • Received:2024-07-20 Revised:2025-01-25 Published:2025-08-07

Abstract: Carbon/Carbon (C/C) composites are indispensable strategic materials for aviation, aerospace, and nuclear energy. Various notches are inevitably introduced in C/C composites to meet the assembly and functional requirements. During loading, various damages affecting the failure load are prone to occur at the edges of the notches. Thus, the effect of the notches on the effective mechanical properties must be considered when designing C/C composite parts. A strategy combining experimental test and numerical calculation is used to helps understand the design of high-performance notched C/C composite parts. Load-bearing capacity and failure morphology of C/C composites are obtained by experiments with various notch sizes. Based on the characteristics of various damages, Hashin, Puck, and quadratic stress criterion are individually adopted to define the damage initiation of carbon fiber, pyrocarbon matrix, and the interlaminar interface. The damage evolution is defined by the energy-based method. The validity of the proposed finite element model is verified by the good agreements between the experimental and numerical ultimate loads and damage distributions. It is found that the load-bearing capacity of C/C composites is significantly affected by the size and distribution of the notches. The ultimate load of C/C composites decreases by 38.5% as the size of notches increases from 1.0 mm to 2.2 mm. The damage initiation displacement of fibers decreases by 16.1% and the ultimate load drops by 17% with the increase of distance between the notches from 0 mm to 12.8 mm. Finally, the research reveals the damage evolution mechanism of the notched C/C composites, which suggests that the composites fail completely as the interlaminar interface damage, matrix damage, and fiber damage appear sequentially during the loading. The design of notched C/C composite parts can be guided by the research results in the future.

Key words: notched C/C composite, damage behavior, load-bearing capacity, numerical calculation, experimental test

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