Abstract
The effect of lay-up on the open-hole shear (OHS) strength of quasi-isotropic carbon fibre/epoxy composite laminates was investigated. It was found that laminates with equivalent specific stiffness but different laminate lay-up, i.e. with different arrangements of plies and ply thicknesses, exhibit significant differences in ultimate OHS strength of up to 16.3% and 27.9% for the prepreg material systems IM7/8552 and T800/epoxy, respectively. Using Digital Image Correlation (DIC), X-ray Computed Tomography (CT), and Finite Element Analysis (FEA), it is shown that the lay-up dependent OHS strengths were associated with distinctly different failure modes. These lay-up dependent failure modes are challenging to predict. It is therefore proposed that the OHS test could be used for material screening, and as a new benchmark case for the development and validation of advanced progressive damage modelling frameworks for laminated composites, complementing the commonly used open-hole tensile (OHT) test.
| Original language | English |
|---|---|
| Article number | 110044 |
| Pages (from-to) | 110044 |
| Number of pages | 10 |
| Journal | Composites Science and Technology |
| Volume | 239 |
| Early online date | 30 Apr 2023 |
| DOIs | |
| Publication status | Published - 11 May 2023 |
Bibliographical note
Funding Information:The combined experimental and numerical analysis presented in the paper provides novel insights into the effect of ply thickness and relative shear loading direction, i.e. into the effect of laminate lay-up, on the strength and failure modes of laminated composite materials. Furthermore, the strong lay-up dependency of the OHS strength makes the OHS experiment suitable for the further development and validation of progressive failure models for advanced composites. Historically, open-hole tension (OHT), and to a lesser extent open-hole compression (OHC), experiments have predominantly been used for the development and validation of progressive damage models, due to their complex lay-up dependent failure behaviour. However, these tests do not trigger all failure mechanisms in composites, and thus models validated against OHT tests alone are not sufficient. The OHS test is therefore a useful additional validation experiment, which can elucidate and critically scrutinise previously unchallenged aspects of the modelling of damage and failure in composites, and thus serve to complement the already established tensile and compressive open-hole testing. Lastly, the experimental data [37] supporting this paper is freely available from the University of Bristol data repository (https://doi.org/10.5523/bris.hlo8uvij8yu02oh26rifpy6ju) and can be widely used for the development and quantitative validation of progressive composite damage models, as well as for the development of novel validation approaches based on full-field DIC data.The research presented was supported by the EPSRC Programme Grant ‘Certification for Design – Reshaping the Testing Pyramid’ (CerTest, EP/S017038/1) and the Faculty of Engineering, University of Bristol. The μ-VIS X-Ray Imaging Centre of the University of Southampton is acknowledged for providing the X-ray CT facilities used. The authors also thank Dr Geir Ólafsson, Bristol Composites Institute, for his help in conducting initial experiments, and Dr Khong Wui Gan, University Southampton – Malaysia Campus, for their inputs in interpreting the results.
Funding Information:
The research presented was supported by the EPSRC Programme Grant ‘Certification for Design – Reshaping the Testing Pyramid’ (CerTest, EP/S017038/1 ) and the Faculty of Engineering, University of Bristol . The μ-VIS X-Ray Imaging Centre of the University of Southampton is acknowledged for providing the X-ray CT facilities used. The authors also thank Dr Geir Ólafsson, Bristol Composites Institute, for his help in conducting initial experiments, and Dr Khong Wui Gan, University Southampton – Malaysia Campus, for their inputs in interpreting the results.
Publisher Copyright:
© 2023 The Authors