近年來，應用破壞力學分析複材結構失效之方法已被驗證 具有可靠性及一致性。然而，由於此方法需要在全域模型中建構幾何複雜之三維實體模型，缺乏高效率的建模及分析工具，使其在工程實務中仍難以被廣泛應用。本研究提出適用於自動化之實用程序以預測複材結構內部疊層減縮區之幾何特徵與結構失效。本研究以Abaqus® 為平台進行程序開發。首先，本程序預測內部疊層減縮區中樹脂囊之截面幾何特徵，且利用此幾何特徵建立內部疊層減縮區之三維實體模型。隨後，利用二階段的子模型分析及膠結元素進行內部疊層減縮區之三維應力分析。最後，應用此程序預測一疊層複材板之結構失效行為。此程序能夠高效率地預測複材結構中內部疊層減縮區之幾何特徵與結構失效，並且能透過撰寫程式將其轉化為CAE工具，以利用於航太結構細部設計的評估。

Over the past decades, fracture mechanics-based approaches for failure analysis in laminated composite structures have been verified to be reliable in predicting structural failure due to stress concentration of the nature of singularity. However, the complexity of creating detailed three-dimensional (3-D) models has hindered engineering practice of the approaches due to the lack of specialized tools. This study proposes practical procedures suitable for automation to predict the geometrical characteristics and structural failure of internal ply-drops in composite laminates. The procedures run within the CAE (computer-aided engineering) environment of the commercial finite element analysis program Abaqus. The cross-sectional geometries of resin pockets in internal ply-drops are predicted by simulating the plastic deformation of the composite material during an idealized layup process. Then, the geometries are simplified and utilized to create a detailed 3-D solid model with the internal ply-drops. In the 3-D model, cohesive elements are inserted between selected plies to predict the onset of delamination. A two-stage global-local analysis is subsequently employed to predict both 3-D intralaminar failure and interlaminar failure around the internal ply-drops. To demonstrate the procedures, a composite panel with internal ply-drops between the acreage and marginal pad-ups is investigated. The value of such detailed analyses emerges in a comparison with a similar panel with external ply-drops instead. The comparison indicates substantial differences in strength and failure behavior between the two panels.

[1] 王五龍 and W.-L. Wang, "分析疊層複材結構內部高曲率與自由邊區域三維應力之CAE工具 = CAE Tools for Analysis of 3-D Stress in Internal High-curvature and Free-edge Zones of Laminated Composite Structures / 王五龍(Wu-Lung Wang)撰," CAE Tools for Analysis of 3-D Stress in Internal High-curvature and Free-edge Zones of Laminated Composite Structures, 國立成功大學航空太空工程學系, 2022.
[2] 黃英慈 and Y.-T. Huang, "複材結構外部疊層縮減區之建模程序與三維應力分析方法 = Modeling Procedure and 3-D Stress Analysis Method for External Ply-drop Zones of Composite Structures / 黃英慈(Ying-Tzu Huang)撰," Modeling Procedure and 3-D Stress Analysis Method for External Ply-drop Zones of Composite Structures, 國立成功大學航空太空工程學系, 2022.
[3] F.-Y. Huang and 黃富語, "使用膠結元素分析疊層複材結構Y形連結之實用程序 = A Practical Procedure for Analysis of Y Joints of Laminated Composite Structures Using Cohesive Elements / Fu-Yu Huang[黃富語]撰," A Practical Procedure for Analysis of Y Joints of Laminated Composite Structures Using Cohesive Elements., 國立成功大學航空太空工程學系, 2023.
[4] S.-L. Leong and 梁斯麟, "使用膠結元素分析複材結構外部曡層縮減區轉折角之實用程序 = A Practical Procedure for Analysis of Corners of External Ply-drop Zones of Composite Structures Using Cohesive Elements / Szi-Lin Leong[梁斯麟]撰," A Practical Procedure for Analysis of Corners of External Ply-drop Zones of Composite Structures Using Cohesive Elements., 國立成功大學航空太空工程學系, 2023.
[5] K. W. Gan, G. Allegri, and S. R. Hallett, "A simplified layered beam approach for predicting ply drop delamination in thick composite laminates," Materials & Design, vol. 108, pp. 570-580, 2016, doi: 10.1016/j.matdes.2016.06.105.
[6] R. B. Pipes, "Moiré Analysis of the Interlaminar Shear Edge Effect in Laminated Composites," Journal of Composite Materials, vol. 5, no. 2, pp. 255-259, 1971/02/01 1971, doi: 10.1177/002199837100500211.
[7] P. Lagace, J. Brewer, and C. Kassapoglou, "The Effect of Thickness on Interlaminar Stresses and Delamination in Straight-Edged Laminates," Journal of Composites Technology and Research, vol. 9, no. 3, pp. 81-87, 1987, doi: 10.1520/ctr10246j.
[8] I. Raju and T. O’brien, "Fracture mechanics concepts, stress fields, strain energy release rates, delamination initiation and growth criteria," in Delamination behaviour of composites: Elsevier, 2008, pp. 3-27.
[9] F. Z. Hu, C. Soutis, and E. C. Edge, "Interlaminar stresses in composite laminates with a circular hole," Composite Structures, vol. 37, no. 2, pp. 223-232, 1997/02/01/ 1997, doi: https://doi.org/10.1016/S0263-8223(97)80014-1.
[10] S. Hallett, J. Lander, M. Jones, L. Kawashita, and M. R. Wisnom, "Testing and modelling of a severely tapered composite specimen," in 5th International Conference on Composites Testing for Model Identification (CompTest), Lausanne, 2011.
[11] Hibbitt, Karlsson, and Sorensen, ABAQUS/standard: User's Manual. Hibbitt, Karlsson & Sorensen, 1997.
[12] Y. R. Larberg and M. Åkermo, "On the interply friction of different generations of carbon/epoxy prepreg systems," Composites Part A: Applied Science and Manufacturing, vol. 42, no. 9, pp. 1067-1074, 2011, doi: 10.1016/j.compositesa.2011.04.010.
[13] Toray Industries, "Carbon Fiber Selector Guide," ed: Toray Industries, , 2021.
[14] G. B. Murri, T. K. O'Brien, and S. A. Salpekar, "Tension fatigue of glass/epoxy and graphite/epoxy tapered laminates," Journal of the American Helicopter Society, vol. 38, no. 1, pp. 29-37, 1993.
[15] R. Krueger and P. J. Minguet, "Analysis of composite panel-stiffener debonding using a shell/3D modeling technique," 2006.