为了揭示轴向压缩载荷与径向冲击载荷共同作用下复合材料壳体开孔处裂纹的产生机理,开展了含圆孔复合材料圆柱壳冲击试验,并对冲击试验进行了有限元仿真分析。提出复杂冲击载荷作用下的动态响应分析方法,运用LS-DYNA对冲击载荷作用下含圆孔复合材料圆柱壳动态响应过程进行了模拟,采用含刚度退化的Chang-Chang失效准则预测复合材料圆柱壳破坏过程,得到的冲击加速度响应曲线及破坏区域与试验结果一致,验证了本文方法的正确性。对有限元模型进行动力学及静力学破坏分析,结果表明,径向冲击引起的环向拉应力是圆孔边缘破坏区域90°铺层纤维断裂与基体开裂的主要原因,而拉应力只引起0°铺层基体开裂。由破坏起始分析可知,将复合材料圆柱壳90°铺层含量由20%提高至50%,可使结构承载能力增加56%。
Impact tests of composite cylindrical shells are performed and a finite element analysis is applied to reveal the damage mechanism of composite cylindrical shells with a circular hole subjected to axial compressive and transverse transient dynamic loads. The method of dynamic response analysis is established. First, the LS-DYNA FEM package is used to simulate the mechanical behaviors of composite cylindrical shells under complex impact loads. Subsequently, damage propagation is predicted by the implementation of the Chang-Chang criterion, which reduces the stiffness components of the corresponding failed elements. A good agreement is achieved between the numerical analysis and experimental results. Both the dynamic and static damage analysis indicates that, along the axial edge of the hole, the damage of the 90? layers, including fiber breakage and matrix cracking, is caused mainly by the circumferential tensile stress induced by transverse impact. However, the tensile stress only causes matrix cracking in the 0? layers. The first-element damage analysis shows that the structure bearing capacity of a composite cylindrical shell may be enhanced by 56% if the contents of the circumferential layers are increased from 20% to 50%.
[1] Khalili S M R, Soroush M, Davar A, et al. Finite element modeling of low-velocity impact on laminated composite plates and cylindrical shells. Composite Structures, 2011, 93(5): 1363-1375.
[2] Tarfaoui M, Gning P B, Hamitouche L. Dynamic response and damage modeling of glass/epoxy tubular structures: numerical investigation. Composites Part A: Applied Science and Manufacturing, 2008, 39(1): 1-12.
[3] Jafari A A, Khalili S M R, Azarafza R. Transient dynamic response of composite circular cylindrical shells under radial impulse load and axial compressive loads. Thin-Wall Structures, 2005, 43(11): 1763-1786.
[4] Azarafza R, Khalili S M R, Jafari A A, et al. Analysis and optimization of laminated composite circular cylindrical shell subjected to compressive axial and transverse transient dynamic loads. Thin-Wall Structures, 2009, 47(8-9): 970-983.
[5] Luo R K, Green E R, Morrison C J. Impact damage analysis of composite plates. International Journal of Impact Engineering, 1999, 22(4): 435-447.
[6] Green E R, Morrison C J, Luo R K. Simulation and experimental investigation of impact damage in composite plates with holes. Journal of Composite Materials, 2000, 34(6): 502-521.
[7] Luo R K. The evaluation of impact damage in a composite plate with a hole. Composites Science and Technology, 2000, 60(1): 49-58.
[8] MD NASTRAN 2010. Quick reference guide. Santa Ana, CA: MSC.Software Corporation, 2010: 2141-2142.
[9] de Moura M F S F, Goncalves J P M. Modeling the interaction between matrix cracking and delamination in carbon-epoxy laminates under low velocity impact. Compo-sites Science and Technology, 2004, 64(7-8): 1021-1027.
[10] Hou J P, Petrinic N, Ruiz C, et al. Prediction of impact damage in composite plates. Composites Science and Technology, 2000, 60(2): 273-281.
[11] Swanson S R. Limits of quasi-static solutions in impact of composite structures. Composites Engineering, 1992, 2 (4): 261-267.
[12] Wardle B L, Lagace P A. Behavior of composite shells under transverse impact and quasi-static loading. AIAA Journal, 1998, 36(2): 1065-1073.
[13] Luo G M, Lee Y J. Simulation of constrained layered damped laminated plates subjected to low-velocity impact using a quasi-static method. Composite Structures, 2009, 88(2): 290-295.
[14] Zheng X X, Zheng X T, Shen Z, et al. Damage equivalent of composite laminates subjected to drop-weight impact and quasi-static indentation force. Acta Aeronautica et Astronautica Sinica, 2010, 31(5): 928-933. (in Chinese) 郑晓霞, 郑锡涛, 沈真, 等. 低速冲击与准静态压痕力下复合材料层合板的损伤等效性. 航空学报, 2010, 31(5): 928-933.
[15] Khan S U, Iqbal K, Munir A, et al. Quasi-static and impact fracture behaviors of CFRPs with nanoclay-filled epoxy matrix. Composites Part A: Applied Science and Manufacturing, 2011, 42(3): 253-264.
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