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Finite Element Study of Thermal Effect on Fibrous Composite Structures during Curing
|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:|| 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.  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.  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.  X. Niu, Process Induced Residual Stresses and Dimensional Distortion in Advanced Laminated Composites, Ph.D. Dissertation, University of Florida, Gainesville, 1999.  S. Timoshenko and S. Woinowsky-krieger, theory of Plates and shells, new york: mcgraw-hill, 1959,pp.120,143,202,206.  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.  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  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.  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.  P. Hubert, Aspects of flow and compaction of laminated composite shapes during cure, Ph.D. Thesis, The University of British Columbia, Vancouver, 1996.  C. A. Felippa, A Solid Shell Element, Report to Center for Aerospace Structure, University of Colorado, Boulder.  J. N. Reddy, Mechanics of Laminated composite plates theory and analysis, Florida: CRC Press, Boca Raton, 1997, pp. 297-445.  JM. Svanberg, Predictions of manufacturing induced shape distortions – high performance thermoset composites, ph.D. Thesis, Lulea University of Lulea, Sweden, 2002.  H. T. Hahn and N. J. Pagano, ”curing stresses in composite laminates,” journal of composite materials, vol. 9, no. 1, 1975, pp. 91-106.  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.  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:||
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.
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