Composites Research

The Korean Society for Composite Materials (한국복합재료학회)
권호 표지
DOI QR코드

DOI QR Code

The Study on the Characteristics of Mode I Crack for Cross-ply Carbon/Epoxy Composite Laminates Based on Stress Fields

응력장을 이용한 직교적층 탄소섬유/에폭시 복합재 적층판의 모드 I 균열 특성 연구

  • Kang, Min-Song (Department of Aerospace Engineering, Chungnam National University) ;
  • Jeon, Min-Hyeok (Department of Aerospace Engineering, Chungnam National University) ;
  • Kim, In-Gul (Department of Aerospace Engineering, Chungnam National University) ;
  • Woo, Kyeong-Sik (School of Civil Engineering, Chungbuk National University)
  • Received : 2019.03.22
  • Accepted : 2019.12.23
  • Published : 2019.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

The delamination is a special mode of failure occurring in composite laminates. Several numerical studies with finite element analysis have been carried out on the delamination behavior of unidirectional composite laminates. On the other hand, the fracture for the multi-directional composite laminates may occur not only along the resin-fiber interface between plies known as interply or interlaminar fracture but also within a ply known as interyarn or intralaminar fracture accompanied by matrix cracking and fiber bridging. In addition, interlaminar and intralaminar cracks appear at irregular proportions and intralaminar cracks proceeded at arbitrary angle. The probabilistic analysis method for the prediction of crack growth behavior within a layer is more advantageous than the deterministic analysis method. In this paper, we analyze the crack path when the mode I load is applied to the cross-ply carbon/epoxy composite laminates and collect and analyze the probability data to be used as the basis of the probabilistic analysis in the future. Two criteria for the theoretical analysis of the crack growth direction were proposed by analyzing the stress field at the crack tip of orthotropic materials. Using the proposed method, the crack growth directions of the cross-ply carbon/epoxy laminates were analyzed qualitatively and quantitatively and compared with experimental results.

층간분리는 복합재 적층판에서 발생하는 특수한 파손 모드이다. 유한요소해석기법을 활용하여 균열 성장방향이 확실히 예측되는 일방향 복합재 적층판의 층간분리 거동과 관련된 많은 수치적 연구가 수행되었다. 반면에 여러 방향으로 적층된 복합재 적층판의 층간분리는 층간 균열 뿐 만 아니라 기지재료 파손 및 섬유 브릿징을 수반하는 층내 균열이 발생한다. 또한 층간 균열과 층내 균열이 불규칙적인 비율로 나타나고 층내 균열도 임의의 각도로 성장한다. 이러한 직교적층 복합재 적층판의 균열 성장 방향에 대한 예측은 확정론적 해석 방법 보다는 확률론적 해석 방법이 유리하다. 본 논문에서는 직교적층 탄소섬유/에폭시 복합재 적층판에 모드 I 하중이 가해질 때 균열 경로를 분석하여 향후 확률론적 해석의 기반 자료로 사용할 수 있는 확률 데이터를 수집하고 분석하였다. 직교이방성 재료의 균열선단에서의 응력장 해석결과를 활용하여 균열 성장 방향을 분석할 수 있는 두 가지 기준을 제안하였다. 제안한 방법을 이용하여 직교적층 탄소섬유/에폭시 복합재 적층판의 균열 성장 방향을 정성적, 정량적으로 분석하고 실험값과 비교분석하였다.

Keywords

References

  1. Kang, M.S., Jeon, M.H., Kim, I.G., and Woo, K.S., "The Characteristics for Mode I Interlaminar and Intralaminar Fractures of Cross-ply Carbon/epoxy Composite Laminates Based on Energy Release Rate," Composites Research, Vol. 32, No. 1, 2019, pp. 6-12.
  2. ASTM D5528-13, Standard Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites, ASTM International, West Conshohocken, PA, 2013.
  3. ASTM D7905 / D7905M-14, Standard Test Method for Determination of the Mode II Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites, ASTM International, West Conshohocken, PA, 2014.
  4. Reeder, J.R., and Rews, J.H., "Mixed-mode Bending Method for Delamination Testing," AIAA Journal, Vol. 28, No. 7, 1990, pp. 1270-1276. https://doi.org/10.2514/3.25204
  5. Borg, R., Nilsson, L., and Simonsson, K., "Simulating DCB, ENF and MMB Experiments Using Shell Elements and a Cohesive Zone Model," Composites Science and Technology, Vol. 64, No. 2, 2004, pp. 269-278. https://doi.org/10.1016/S0266-3538(03)00255-0
  6. Harper, P.W., and Hallett, S.R., "Cohesive Zone Length in Numerical Simulations of Composite Delamination," Engineering Fracture Mechanics, Vol. 75, No. 16, 2008, pp. 4774-4792. https://doi.org/10.1016/j.engfracmech.2008.06.004
  7. Camanho, P.P., Davila, C.G., and De Moura, M., "Numerical Simulation of Mixed-mode Progressive Delamination in Composite Materials," Journal of Composite Materials, Vol. 37, No. 16, 2003, pp. 1415-1438. https://doi.org/10.1177/0021998303034505
  8. De Morais, A., De Moura, M., Marques, A., and De Castro, P., "Mode-I Interlaminar Fracture of Carbon/epoxy Cross-ply Composites," Composites Science and Technology, Vol. 62, No. 5, 2002, pp. 679-686. https://doi.org/10.1016/S0266-3538(01)00223-8
  9. Chalivendra, V.B., "Mode-I Crack-tip Stress Fields for Inhomogeneous Orthotropic Medium," Mechanics of Materials, Vol. 40, No. 4-5, 2008, pp. 293-301. https://doi.org/10.1016/j.mechmat.2007.09.001
  10. Anderson, T.L., Fracture Mechanics: Fundamentals and Applications, CRC Press, 2017.
  11. Krenk, S., "On the Elastic Constants of Plane Orthotropic Elasticity," Journal of Composite Materials, Vol. 13, No. 2, 1979, pp. 108-116. https://doi.org/10.1177/002199837901300202
  12. Wei, Y., "A Stochastic Description on the Traction-separation Law of an Interface with Non-covalent Bonding," Journal of the Mechanics and Physics of Solids, Vol. 70, 2014, pp. 227-241. https://doi.org/10.1016/j.jmps.2014.05.014
  13. De Moura, M., Campilho, R.D., Amaro, A., and Reis, P., "Interlaminar and Intralaminar Fracture Characterization of Composites under Mode I Loading," Composite Structures, Vol. 92, No. 1, 2010, pp. 144-149. https://doi.org/10.1016/j.compstruct.2009.07.012