基于FBG传感技术的复合材料加筋板低速冲击损伤监测

针对碳纤维增强树脂基复合材料低速冲击损伤的实时监测,本文设计将布拉格光纤光栅(FBG)传感器埋植在复合材料加筋板结构的三角填充区,在线监测复合材料T型加筋板冲击损伤过程。分别将FBG传感器埋植于复合材料层合板内部和复合材料T型加筋板的三角填充区,对比FBG传感器的埋入对复合材料层合板与复合材料T型加筋板对力学性能的影响,结果表明内埋FBG传感器的复合材料层合板试样的拉伸强度比未埋植传感器的层合板试样降低了约5%,但在FBG传感器的破坏应变范围内,FBG传感器可以准确、实时地监测复合材料的应变信号。将FBG传感器埋入复合材料T型加筋板的三角填充区,内埋FBG传感器的加筋板样件压缩破坏载荷与未埋植的样件基本一致。通过对比加筋板蒙皮上冲击位置、冲击能量对FBG传感器测得的冲击过程持续时间和最大应变值的影响,表明冲击过程持续时间随着冲击能量增加而延长,最大应变值随着冲击距离的增加呈下降趋势,而最大应变值随着冲击能量的增加呈上升趋势。利用FBG传感器测得的应变信号可初步实现对复合材料T型加筋板蒙皮冲击损伤位置及冲击能量的实时监测。国家重点研发计划(2016YFD0700603);;航空科学基金(2016ZF68011);;江苏省重点研发计划(BE2015007);;福建省科技创新平台建设计划(2014H2006

酚酞聚芳醚酮-双马来酰亚胺体系流变行为时间-温度依赖性

采用流变仪对酚酞聚芳醚酮(PEKC)-双马来酰亚胺(BMI)树脂体系的流变特性的时间和温度依赖性进行了研究,发现:BMI树脂凝胶点对频率有依赖性,而tanδ对频率无依赖性;PEKC-BMI复合树脂体系的黏度增大主要是由于BMI对PEKC的溶解与BMI的热固化。相比较110℃和130℃两种条件,在较高温度时复合树脂体系的黏度增大主要是热固化的影响;随注胶温度提高,复合体系的凝胶时间随PEKC含量的增加而快速缩短,在较高注胶温度下凝胶模量增大较慢,在较低注胶温度下凝胶时模量随PEKC含量的增加而提高较快;随着复合树脂体系中PEKC含量的增加,该体系的凝胶活化能由4.9kJ/mol增大到65.9kJ/mol,表明该体系的凝胶化作用对温度的敏感性增大

the thinking of commercial airplane composites technology which lead fiber industry to develop

以波音、空客两大商用飞机制造公司复合材料技术现状为例,就纤维复合材料在大型飞机中的应用技术进行阐述与分析.表明大型飞机中纤维复合材料的用量已成为评价航空技术先进程度的一项重要指标.结合我国大飞机项目在纤维产业方面所面临的问题,提出一些思考

结构化增韧层增韧RTM复合材料性能

从复合材料离位增韧思想出发,选用具有高孔隙率的尼龙无纺布(PNF)作为结构化增韧层,采用RTM工艺制备了PNF层间增韧改性的U3160碳纤维增强环氧3266树脂基复合材料(U3160-PNF/3266),并研究了其韧性相关性能和增韧机制。结果表明:U3160-PNF/3266复合材料层间仍保持其原有的结构形式,同时与层间树脂相互贯穿形成了一种非反应诱导相分离的双连续结构,并且这种双连续结构表现出显著的增韧效果。U3160-PNF/3266复合材料的Ⅰ型层间断裂韧性和Ⅱ型层间断裂韧性分别提高了1.1倍和1.4倍,冲击后压缩强度由212MPa提高到281MPa

Research of Processing Characteristics and Mechanical Properties of Semi-prepreg RTM Composites

针对rTM成型工艺中的定型、预制问题,提出了一种新型的贫胶预浸料-rTM成型工艺。采用湿法预浸工艺制备了贫胶预浸料及正常胶含量的预浸料,对比了贫胶预浸料-rTM工艺成型的复合材料及预浸料模压工艺成型的复合材料的力学性能。实验结果表明,rTM工艺过程中,树脂的流动充模过程可以有效排除附着于贫胶预浸料中的气体,减少孔隙等缺陷出现的概率,复合材料的内部质量能够得到有效地保证。同时,力学性能测试表明,贫胶预浸料-rTM工艺成型的复合材料的层间剪切性能及冲击后压缩性能优于预浸料模压工艺成型的复合材料。A novel semi-prepreg resin transfer molding( RTM) process was developed to address difficulties associated with RTM process and to improve the mechanical properties of the resulting composites.Unidirectional semi-prepregs exhibiting relatively good overlay characteristics were prepared via prepolymerization of bismaleimide resin followed by wet winding.The processing characteristics and mechanical properties of composites fabricated via semi-prepreg RTM technology were compared with those of composites produced using a normal-prepreg compression molding process.The results show that the laminates fabricated by the semi-prepreg RTM process are of better internal quality and have superior mechanical properties as compared with laminates fabricated by the normal-prepreg compression molding process.国家自然科学基金(51203144;51103121); 航空科学基金(20115221003;20125268002); 国家973课题(2010CB631101

Permeability of toughened RTM composite preforms by structural toughening layer

选用尼龙无纺布(POlyAMIdE nOnWOVEn fAbrIC,Pnf)作为结构化增韧层,研究了增韧层的引入对纤维预成型体在树脂传递模塑成型(rTM)工艺过程中渗透特性的影响。结果表明:在径向非饱和流动模式下,层间增韧预成型体沿纤维方向的渗透率为5.2x10-12 M2,略低于非增韧预成型体的7.1x10-12 M2,而沿垂直于纤维方向的渗透率为2.3x10-12 M2,略高于非增韧预成型体的1.6x10-12 M2。此外,层间增韧预成型体的单向饱和流动渗透率为2.6x10-12 M2,较非增韧预成型体的1.9x10-11 M2下降了约1个数量级,z向饱和流动渗透率较非增韧预成型体的1.3x10-13 M2下降至2.5x10-14 M2,同样下降了约1个数量级。对复合材料层间微观形貌的分析结果表明:造成预成型体渗透率下降的主要原因首先是Pnf引入至层间之后将阻碍层间树脂的快速流动,同时增韧层将使层内纤维含量明显升高,由55.3VOl%上升到63.7VOl%。The nylon nonwoven fabric(Polyamide Nonwoven Fabric,PNF)was selected as structural toughening layer to investigate its effect on the permeability of fiber preforms during resin transfer molding(RTM)process.Results show that under unsaturated radial flow pattern,the permeability of the interlaminar toughened preform along the direction of fiber(5.2×10-12 m2)is lower than that of the untoughened preform(7.1×10-12 m2).On the contrary,the permeability of the toughened preform perpendicular to the fiber direction(2.3×10-12 m2)is higher than that of the untoughened preform(1.6×10-12 m2).Moreover,the unidirectional saturated flow permeability of interlaminar toughened preform is 2.6×10-12 m2,which is much lower than that of untoughened preform(1.9×10-11 m2),decreased by an order of magnitude.The z-directional saturated permeability also dramatically decreases from 1.3×10-13 m2(untoughened preform)to 2.5×10-14 m2,decreased by an order of magnitude.The interlaminar morphology analysis results reveal that the decrease of the permeability of preform mainly results from the inhibition of rapid flow of resin,introduced by PNF as structural layers and the increment of interlaminar fiber contents rising from 55.3vol%to 63.7vol%.国家自然科学基金(51203144

CARBON NANOTUBE FILM INTERLAYER TOUGHENED CARBON FIBER REINFORCED EPOXY RESIN HYBRID COMPOSITES

采用碳纳米管膜作为碳纤维/环氧树脂复合材料的层间改性材料,应用液态成型树脂传递模塑工艺制备了碳纳米管膜/碳纤维/环氧树脂混杂复合材料,利用Ⅰ型层间韧性与Ⅱ型层间韧性表达了其韧性相关性能,并分析了改性机理.碳纳米管膜在混杂复合材料层间仍然保持其原有连续网格结构形式,这种形式对张开型Ⅰ型层间断裂韧性没有明显的改性作用,但对于滑移型Ⅱ型层间断裂韧性具有显著的改性效果.碳纳米管膜/碳纤维/环氧树脂混杂复合材料的Ⅱ型层间断裂韧性从碳纤维/环氧树脂复合材料的1292 J/M2提高到了2869 J/M2,提高了120%.材料微观形貌分析表明,这种由碳纳米管相互交叠、缠结而形成的网络结构有效地阻碍了层间微裂纹的扩展.Carbon nanotube film(CNTF) interlayer toughened carbon fiber(CF) reinforced epoxy resin(EP) hybrid composites were fabricated via resin transfer molding(RTM) processing in this paper.Multiwalled carbon nanotubes were prepared by chemical vapour deposition,and carbon nanobute films were prepared through vacuum filtration.Model I interlaminar fracture toughness G IC of laminates and model II interlaminar fracture toughness G IIC of laminates are used to characterize the fracture toughness of the RTM laminates.Furthermore,the toughening mechanism is discussed through microstructure of the fracture surface combining mechanical properties.The compact degree of the carbon nanotube films was influenced by the ratio of the multi-walled carbon nanotubes,which led to different impregnation of the carbon nanobute films to the epoxy resin.Experimental results indicated that the carbon nanotube films from carbon nanotubes of large aspect ratios exhibited better impregnation effect than those films from carbon nanotubes of small aspect ratios.The carbon nanotube films intercalated in the interlayer of the composites between the carbon fiber and the matrix resin as a whole laminated structure,and they still kept a continuous grid structure in the CNTF/CF/EP hybrid composites.As to the model I interlaminar fracture toughness GIC of laminates,the carbon nanotube films have no obvious improvement on the GIC value.However,the carbon nanotube films laid between the carbon fiber layers changed the failure mode of the CF/EP composites,leading to increased initial failure load and breaking load.As to model Ⅱ interlaminar fracture toughness GⅡC of laminates,experimental results exhibited that the reinforcing efficacy on the sliding mode shear failure was remarkably increased for the CNTF/CF/EP hybrid composites.Model Ⅱ interlaminar fracture toughness GⅡC of laminates has increased from 1292 J/m2 of the CF/EP to 2869 J/m2 of the CNTF/CF/EP hybrid composites.There is 120% amplification in GⅡC testing value.Microstructures of the CF/EP composites and the CNTF/CF/EP hybrid composites were characterized through scanning electron microscope(SEM) for understanding the prominent improvement on the toughening properties.SEM pictures showed that there was strong shear history of the carbon nanotube films via the sliding mode failure.The carbon nanotubes absorbed a great deal of energy through shear sliding and hindered crack growth,leading to increase of the GⅡC value outstandingly.国家自然科学基金(基金号51103121;51203144); 航空科学基金(基金号20115221003;20125268002); 高等学校博士学科点专项科研基金(基金号20090121120036); 厦门市科技计划项目(项目号2010S0720); 福建省重大科技平台建设基金(基金号2009J1009)资助项