In situ investigation of failure in 3D braided SiCf/SiC composites under flexural loading

Changqi Liu, Yang Chen, Duoqi Shi, James Marrow, Xin Jing, Xiaoguang Yang

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21 Citations (SciVal)

Abstract

The mechanical failure of three-dimensional (3D) 4-step braided SiCf/SiC composites, processed by precursor infiltration pyrolysis, has been studied under flexural loading to investigate the condition at failure. The investigation integrated the advantages of continuous data acquisition by optical imaging and 3D reconstruction of internal structure in X-CT imaging, for in situ investigation of microstructure-related failure mechanisms. Optical imaging with digital image correlation acquired the surface displacements. X-ray computed tomographs, obtained in situ, were analysed by digital volume correlation to measure the 3D displacement fields. Image subtraction, informed by the 3D displacements, was used to detect and visualize crack development. Curvature measurement, via the displacement fields, monitored the change in effective flexural modulus. The observed failure modes included matrix cracking, inter- and intra-bundle debonding and fibre breakage. Tensile cracks were arrested by the heterogeneous microstructure, and the ultimate failure under flexural loading was due to multiple cracking in compression.

Original languageEnglish
Article number114067
JournalComposite Structures
Volume270
Early online date6 May 2021
DOIs
Publication statusPublished - 15 Aug 2021

Bibliographical note

Funding Information:
This work was supported by the National Natural Science Foundation of China [grant numbers 51772009 and 51911530201 ]. We acknowledge EPSRC Grant EP/M02833X/1 “University of Oxford: experimental equipment upgrade” that supported the Xradia Versa 510 microscope and facilities for data analysis and visualization. The authors want to express their gratitude to Camille Chateau and Michel Bornert from Laboratoire Navier/Ecoles des Ponts ParisTech for the software support relating to image subtraction calculation. The work was conducted at the University of Oxford, with Beihang University support for Liu Changqi as a recognised student. The first and second generation fibres (KD-1 and KD-2) were produced by the National University of Defense Technology, who also provided the Series 1 specimens. The Series 2 specimens were provided by the School of Physics and Nuclear Energy Engineering of Beihang University.

Keywords

  • Braided composites
  • Digital image correlation
  • Failure
  • Flexural loading
  • SiC/SiC
  • X-ray computed tomography

ASJC Scopus subject areas

  • Ceramics and Composites
  • Civil and Structural Engineering

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