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Acta Aeronautica et Astronautica Sinica ›› 2024, Vol. 45 ›› Issue (20): 429966.doi: 10.7527/S1000-6893.2024.29966

• Material Engineering and Mechanical Manufacturing • Previous Articles    

Numerical study on curing residual stresses in compression of Z-pinned composites

Shengnan ZHANG, Yingjie XU(), Weihong ZHANG   

  1. School of Mechanical Engineering,Northwestern Polytechnical University,Xi’an 710072,China
  • Received:2023-12-12 Revised:2024-01-15 Accepted:2024-04-19 Online:2024-05-07 Published:2024-04-30
  • Contact: Yingjie XU E-mail:xu.yingjie@nwpu.edu.cn
  • Supported by:
    National Key Research and Development Program of China(2021YFF0500100);National Natural Science Foundation of China(12220101002)

Abstract:

The Z-pinning technology can effectively improve the interlaminar properties of composite materials, yet the implantation of Z-pins causes fiber distortion, resin-rich zones, and reduced in-plane properties. This paper proposes a numerical method to predict the in-plane compressive properties of Z-pinned composites, with curing effects into consideration. A representative unit cell model is established by analyzing the fine morphology of the Z-pinned structure. Considering the time-dependent properties of the cure process, we develop a coupled thermo-chemo-mechanical multi-field model for Z-pinned structures. The residual stress field obtained from the previous calculation is introduced as a predefined field in the calculation of in-plane compressive performance, and the simulated results are in good agreement with the experimental results. It is found that a large amount of residual stress accumulates around the Z-pin during the cure. Therefore, under compressive loads, weaker material properties around the Z-pin will first develop crack defects, gradually extending to the resin-rich regions. The presence of fiber orientation, resin-rich regions, and cure-induced residual stresses significantly reduce the in-plane compressive performance of Z-pinned composites.

Key words: Z-pin, composites, fiber distortion, cure process, residual stress, finite element analysis, compressive properties

CLC Number: