13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- 3. Conclusions and prospect Based on the test data and analysis, it can be concluded as follows: (1) The crack opening contour of AHL is typically regular, that is be the maximum value at the saw-cut tip, be zero at the crack tip, nearly remaining a constant value in the middle. And the data of crack opening contour is suitable for cubic polynomial fitting. (2) The crack opening contour becomes larger as the stress level or saw-cut length rises when the other condition is the same. (3) Delamination shape between inner aluminium alloy sheet and prepreg stays the same basically, that is be nearly zero at the crack tip, increase from crack tip to saw-cut tip, and decrease slightly near the saw-cut tip. (4) The delamination size increases as the stress level rises when the other condition is the same. The influence of saw-cut length on delamination behavior is not distinct. Because of the balance of bridging stress, crack opening contour and delamination, there is significance for the data of crack opening contour, delamination shape and size displayed in this research, which can support the creation and verification of fatigue crack propagation predict model for AHL. Acknowledgements Advanced hybrid laminates were prepared by Post Doctor Shigang Bai and Master Shiyu Wang in Harbin Institute of Technology. Specimen processing and fatigue crack propagation test were finished with great help of Engineer Shufen Li in Beijing Institute of Aeronautical Materials and Professor Liyang Xie, Professor Ruijin Zhang, Doctor Anshi Tong in Northeastern University (China). I would like to express my heartfelt gratitude to all the people mentioned above. References [1] A. Vlot, J.W. Gunnink, Fibre Metal Laminates, an introduction, Kluwer Academic Publishers, Dordrecht, The Netherlands, 2001. [2] Geert H.J.J. Roebroeks, Peter A. Hooijmeijer, Erik J. Kroon. The development of CentrAl. First International Conference on Damage Tolerance of Aircraft Structures. 2007. [3] Robert S. Fredell, J.W. Gunnink, R.J. Bucci, Jens Hinrichsen, "Carefree" hybrid wing structures for aging USAF transports, First International Conference on Damage Tolerance of Aircraft Structures. 2007. [4] R. Marissen, Fatigue Crack Growth in ARALL, A hybrid Aluminium-Aramid Composite Material, crack growth mechanisms and quantitative predictions of the crack growth rate, PhD Thesis, Delft University of Technology, 1988. [5] Y.J. Guo, X.R. Wu, A theoretical model for predicting fatigue crack growth rates in fibre-reinforced metal laminates, Fatigue Fract Eng Mater Struct, 21 (1998) 1133–1145. [6] Y.J. Guo, X.R. Wu, Bridging stress distribution in center-cracked fiber reinforced metal laminates: modelling and experiment, Eng Fract Mech, 63 (1999) 147–163. [7] Y.J. Guo, X.R. Wu, A phenomenological model for predicting crack growth in fiber-reinforced metal laminates under constant-amplitude loading, Compos Sci Technol, 59 (1999) 1825–1831. [8] T. Takamatsu, T. Matsumura, N. Ogura, T. Shimokawa, Y. Kakuta, Fatigue crack growth of a GLARE3-5/4 fiber/metal laminate and validity of methods for analysing results, 20th symposium international committee on aeronautical fatigue, Bellevue Washington, USA, 1999. [9] D.A. Burianek, Mechanics of fatigue damage in titanium-graphite hybrid laminates, PhD thesis, Massachusetts Institute of Technology, 2001. [10] Y.J. Guo, X.R. Wu, Fatigue behaviour and life prediction of FRML under CA and VA loading, Fatigue Fract Eng Mater Struct, 25 (2002) 417–432. [11] Wu XJ. A higher-order theory for fiber–metal laminates. In: Proceedings of the 23rd
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