Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2904
標題: 纖維複材固化之熱效應的有限元素研究
Finite Element Study of Thermal Effect on Fibrous Composite Structures during Curing
作者: 鄭登勳
Cheng, Teng-Hsun
關鍵字: 有限元素;finite elements;纖維殼元素;熱壓爐影響;fiber shell element;autoclave thermal effect
出版社: 機械工程學系所
引用: [1] A. Johnston, An integrated model of the development of process induced deformation in autoclave processing of composite structures, Ph.D. thesis, University of British Columbia, 1997. [2] G. Twigg, A. Poursartip and G. Fernlund, ” Tool-part interaction in composites processing. Part I: experimental investigation and analytical model,” Composites Part A-applied Science And Manufacturing, vol.35, no.1, 2004, pp. 121–133. [3] G. Fernlund and A. Poursartip, “The Effect of Tooling Material, Cure Cycle, and Tool Surface Finish on Spring-in of Autoclave Processed Curved Composite Parts,” Proceedings of the 12th International Conference on Composite Materials, Paris, France, 1999, pp. 5-9. [4] X. Niu, Process Induced Residual Stresses and Dimensional Distortion in Advanced Laminated Composites, Ph.D. Dissertation, University of Florida, Gainesville, 1999. [5] S. Timoshenko and S. Woinowsky-krieger, theory of Plates and shells, new york: mcgraw-hill, 1959,pp.120,143,202,206. [6] B. L. Wong, T. Belytschko and H. Stolarskl, ”Assumed strain stabilization procedure for the 9-node lagrange shell element,” International Journal for Numerical Methods in Engineering, vol. 28, no. 2, 1989, pp. 385-414. [7] A. M. Farid and C. Alain, “ locking-free formulation for the stabilized enhanced strain solid shell Element (shb8ps): geometrically non-linear applications,” Proceedings of 6th international conference on Computation of shell & spatial structure, Ithaca, New York, USA, 2008, pp.1-4 [8] R. H. MacNeal and R. L. Harder, “ A proposed standard set of problems to test finite element accuracy,” Journal of Finite Elements in Analysis and Design, vol. 1, 1985, pp. 3–20. [9] W. K. Liu, Y. Guo, S. Tang, T. Belytschko, ” A multiple-quadrature eight-node hexahedral finite element for large deformation elastoplastic analysis,” Computer Methods in Applied Mechanics and Engineering, vol. 154, no. 1, 1998, pp. 69–132. [10] P. Hubert, Aspects of flow and compaction of laminated composite shapes during cure, Ph.D. Thesis, The University of British Columbia, Vancouver, 1996. [11] C. A. Felippa, A Solid Shell Element, Report to Center for Aerospace Structure, University of Colorado, Boulder. [12] J. N. Reddy, Mechanics of Laminated composite plates theory and analysis, Florida: CRC Press, Boca Raton, 1997, pp. 297-445. [13] JM. Svanberg, Predictions of manufacturing induced shape distortions – high performance thermoset composites, ph.D. Thesis, Lulea University of Lulea, Sweden, 2002. [14] H. T. Hahn and N. J. Pagano, ”curing stresses in composite laminates,” journal of composite materials, vol. 9, no. 1, 1975, pp. 91-106. [15] E. Carrera and S. Brischetto, “Analysis of thickness locking in classical, refined and mixed theories for layered shells,” Composite structures, vol. 85, no. 1, 2008, pp. 83–90. [16] Luo Yunhua, “Explanation and elimination of shear locking and membrane locking with field consistence approach,” Computer Methods in Applied Mechanics and Engineering, vol. 162, no. 1, 1998, pp. 249-269.
摘要: 
近年來航空器的機體次結構大量地採用複合材料,以增加結構強度與減輕重量,因而該複材結構的製造品質成為各製造廠有待精進的一個主要的設計主題。通常,複材結構的進爐成化製程會由於金屬模具以及成型纖維之間的應力互制行為而使得成型結構與原有的設計形狀產生差距,亦或至於產生殘留應力而影響到成型結構件的品質。如何準確分析這種合成結構的成化應力行為就變成一項很重要的設計主題。
纖維複材是一種非常薄的板殼件,利用一般的有限元素板殼元素來模擬這種纖維複材,並無法得到實際的結構行為了解。而模具則是一個很大型的實體結構。當這兩種結構體結合在一起使用有限元素法分析的時候,會由於兩者元素的力學行為無法吻合,經常會造成困擾,而且計算結果的爭論性也很高。本研究主要是研發一種可與實體元素行為相容的纖維複材薄板殼元素,來分析複材結構與模具膠合結構的出爐冷卻過程所產生的冷縮應力。瞭解這些冷縮應力以後,設計人員可以對纖維複材構件予以適當的修改,使得成型的結構件在使用的時候可以正確發揮設計的運作功效。
本研究首先探討前述的纖維薄殼元素的理論以及有限元素公式的推導。然後寫成電腦程式連結本實驗室自行發展的有限元素分析軟體FEAST系統,再從事一系列之模擬分析測試,以了解固體元素與這種纖維薄板元素的精準度與特性。最後我們建立模具以及複材纖維結構的有限元素模式。再用FEAST軟體執行分析。所得結果可提供該複材結構設計及製造之參考。

In recent years, many of the fibrous composite materials have been applied to aircraft structures in order to increase the structural strength and reduce weights. The quality and function of such composites parts become important in aircraft designing/manufacturing fields. The constrained effect in stresses between metallic molds and the composite fibers during curing in autoclave may cause the geometry unexpectedly changed on composites parts. Moreover, the residual stresses may also generate and affect the quality of the fibrous structures. Correct way of predicting the mechanical behavior on such synthetic structures becomes a very important design and manufacturing subject.
In the finite element analysis, the fiber composite material is a layered and very thin shell structure which is usually simulated by general shell/plate elements directly. Alternately, the mold is a very large structure generally simulated by solid brick element. The discrepancy of characteristics of these two elements may cause structural behavior inconsistency while connected. The computational results appear high controversy. In the study, a fiber composite thin shell element has developed which keeps a compatible nodal behavior with the solid elements. The element may be used for analyzing the contraction stress between the fibrous composites structure and molds in cooling process. Thus, the aircraft structure designers can appropriately modify the design of fiber composite parts to ensure structural operational function and safety.
Here, the fundamental theory of fiber thin shell elements is introduced and the corresponding finite element formula is derived. A specifically designed computer program written in F95 is implemented which links to FEAST system, a FEM software system developed by our laboratory. A series of numerical tests are demonstrated to understand the characteristics and ensure the accuracy of such composite structures. A finite element model of molds and composite fiber parts in aero-curing is built and analyzed by the software developed here. The computational results can provide significant information for aero-structure designers and manufacturers and even other related fields.
URI: http://hdl.handle.net/11455/2904
其他識別: U0005-2708201323322700
Appears in Collections:機械工程學系所

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