泡沫夹层结构复合材料的研究进展

泡沫夹层结构复合材料是由面板(蒙皮)与轻质泡沫芯材组成的层状结构复合材料。该文从泡沫夹层结构的芯材种类、泡沫夹层结构复合材料的力学性能、电性能等方面综述了泡沫夹层结构复合材料近年来的研究现状。     

短切碳纤维对GF-Fabric/EP夹层复合材料的增强作用研究

针对高速列车、新能源汽车等交通工具对高性能泡沫夹层复合材料的迫切需求，制备了玻璃纤维三维立体织物增强环氧树脂泡沫复合材料（下称GF-Fabric/EP复合材料）及其夹层结构，并重点探索短切碳纤维（Short carbon fiber,SCF）对其泡沫本身及夹层复合材料的增强作用。研究结果表明，SCF的填充通过受载时阻断环氧树脂泡沫内部裂纹的扩展，利用自身断裂及与基体脱粘等消耗能量，显著提升环氧树脂泡沫的力学性能，并可与玻璃纤维三维立体织物实现协同增强效果，在填充质量比为2%时复合材料力学性能最佳。同时，基于纤维的“桥联”作用，SCF的引入亦可有效改善铝合金面板与芯材的界面性能。     

双向格构腹板增强泡沫夹层复合材料梁弯曲性能试验

复合材料夹层结构具有比强度高、比刚度高、可设计性强、耐腐蚀等特点,以聚氨酯泡沫为芯材,以玻璃纤维增强复合材料为面板和格构腹板,采用真空导入成型工艺,制备双向格构腹板增强泡沫夹层复合材料梁。对无格构泡沫夹芯复合材料梁,不同腹板高度、腹板间距双向格构增强泡沫夹层复合材料梁进行三点弯曲试验,研究其破坏模式和机理。基于泡沫填充矩形蜂窝芯材的等效十字模型,预估试件的抗弯刚度和挠度,计算值与试验值吻合较好。     

格构增强型复合材料夹层结构的制备与受力性能

真空导入成型工艺是一种新型的适合大型/异型复合材料结构件成型的技术.选用H-60 PVC泡沫、四轴向玻璃纤维布以及乙烯基酯树脂,通过在泡沫芯材上、下表面开槽,同时沿芯材厚度方向剖开,采用真空导入成型工艺制备出在结构上具有创新构型的格构增强型复合材料夹层结构.研究结果表明,真空导入成型工艺充模速度快、成型效益高;格构增强型复合材料夹层结构的剪切、平压与抗弯性能均较传统夹层结构得以提高;其格构腹板可有效抑制泡沫芯材剪切裂纹的扩展,避免面板与芯材的剥离破坏;阐明了格构增强型复合材料夹层结构的受弯极限承载能力.     

含圆形脱粘缺陷复合材料夹层结构侧向压缩破坏载荷与破坏模式分析

为分析含脱粘缺陷复合材料夹层结构侧压破坏载荷与破坏模式,采用损伤起始判据和损伤演化准则模拟面板与胶层的损伤及破坏过程,建立了考虑材料失效的三维渐进损伤分析模型。针对两种典型复合材料夹层结构,基于所建立的模型完成了破坏载荷预估和破坏模式分析,并将有限元分析与试验结果进行了对比。结果表明:面板较弱时,中部含圆形脱粘缺陷夹层结构侧压破坏模式通常为材料失效压缩破坏,随着载荷的增加,面板中部及脱粘区域周围发生损伤并沿板宽度方向向两侧扩展,直至材料完全损伤发生破坏;面板较强时,侧压破坏模式通常为整体失稳破坏,屈曲后结构基本不再具有继续承载的能力而迅速发生破坏。分析结果破坏载荷预估值与试验吻合较好,破坏模式与试验结果一致。     

芯材密度对复合材料夹层梁弯曲力学性能影响

研究了聚氨酯泡沫密度对复合材料夹层梁弯曲力学性能的影响。首先,对5种不同密度(48~413kg/m3)泡沫芯材复合材料夹层梁进行三点弯试验研究,结果表明,夹层梁极限承载力随芯材密度的增大而增大;当芯材密度大于等于199kg/m3时,继续增大泡沫密度,夹层梁极限承载力增加速度变慢;随着芯材密度的增加,夹层梁破坏模式由芯材压陷变为面板受压屈服破坏。其次,基于考虑芯材竖向压缩变形的高阶剪切变形理论,对不同试验梁弯曲受力机理进行弹性分析,得到夹层梁上、下面板挠度变化及应变分布规律,并与试验结果对比,验证了理论分析方法的正确性。最后,对试验过程中夹层梁典型的破坏模式进行极限承载力分析,提出其极限承载力计算公式,并与试验结果对比,结果吻合良好。     

PMI泡沫夹层碳纤维复合材料的制备及力学表征

由于具有较好的力学性能和工艺稳定性,聚甲基丙烯酰亚胺(PMI)泡沫夹层结构在航空领域得到了大量的应用。目前飞机上通常采用预浸料与泡沫热压罐固化制造夹层结构,这种工艺成本较高且只能保证贴模面的表面质量。本文中采用闭模液体成型工艺制备了质量稳定的泡沫夹层结构,对比了同时注胶与交替注胶的制备方法,结果表明交替注胶可以得到更好的成型质量。并对泡沫芯材的力学性能进行了测试,在此基础上建立了泡沫材料的失效模型,并通过有限元分析了其三点弯曲、侧压屈曲等力学性能,有限元模型分析结果与实际测试结果基本一致,有限元模型可揭示在这些加载条件下夹层结构的破坏机理及渐进损伤过程,研究结果可推动高性能的航空用复合材料夹层结构的低成本化制备以及结构服役的虚拟试验。     

NACA构型泡沫夹层复合材料空气风门的结构强度分析

泡沫夹层复合材料具有比强度、比刚度大,保温隔热性能优异等优点,广泛应用于航空航天等诸多领域,在飞机上则应用于一些载荷不大而厚度较小的部件或结构。研究的NACA构型泡沫夹层复合材料空气风门以其材料的特殊性,在组合工况下受力情况复杂,目前对其在多工况下进行强度分析的相关研究较少。以NACA构型的泡沫夹层碳纤维复合材料空气风门为研究对象,建立了有限元模型。通过重点对多工况下风门壳体的等效应力分布情况进行对比和分析,并对夹层结构各层的应力危险区域进行强度校核,得到了各工况下复合材料面板层和泡沫芯材层的应力敏感区域和失效情况,以及载荷对模型应力影响的规律。     

航天航空泡沫夹层结构的设计

<正>1夹层结构的介绍夹层结构是一种层合复合材料的特殊形式,它是由不同材料相互粘接组合,通过利用各个组分的性能特点达到整个系统组成的结构优势。夹层结构一般是由上面板、上面板与芯材的粘结层、芯材、下面板与芯材的粘结层以及下面板所构成,这五个要素组成了一个整体的夹层结构。在构造上通常是采用厚度较薄、强度高、刚度大的材料作为面板,而用密度小、厚度较     

全高度泡沫夹芯结构胶接共固化制造工艺

采用德固赛的ROHACELL PMI结构泡沫为芯材,通过实验验证PMI泡沫的膨胀量为5%,发明了一种刚性泡沫夹层结构"软-硬模"共固化成型的工艺方法,分析了成型压力对泡沫及全高度泡沫的产品性能的影响。此工艺借助复合材料软模,可以整体制造无人机全高度泡沫夹芯舵面类结构,已经通过飞行验证。     

The impact response of aluminum foam sandwich structures based on a glass fiber-reinforced polypropylene fiber-metal laminate

The fracture properties and impact response of a series of aluminum foam sandwich structures with the glass fiber–reinforced polypropylene-based fiber-metal laminate (FML) skins have been studied. Initially, the manufacturing process for producing the FML skins was optimized to obtain a strong bond between the composite plies and the aluminum layers. The degree of adhesion between the composite plies and the aluminum was characterized by conducting single cantilever beam tests. Here, it was found that the composites could be successfully bonded to the aluminum using a simple short stamping procedure. A detailed examination of the fracture surfaces indicated that crack propagation occurred within the composite ply in the fiber-metal laminates and along the composite-aluminum foam interface in the sandwich structures. The low velocity impact response of the FMLs and the sandwich structures was investigated using an instrumented drop-weight impact tower and a laser-Doppler velocimeter. The energy absorption characteristics of the sandwich structures were investigated along with the failure processes. Finally, a series of tensile tests on the damaged FMLs and thermoplastic sandwich structures showed that both systems offer promising residual load-bearing properties. Here, shear failure in the aluminum foam was observed in the sandwich structures, indicative of a strong bond between the FML skins and the aluminum core. Polym. Compos. 25:499–509, 2004. © 2004 Society of Plastics Engineers.     

Peel strength improvement of foam core sandwich beams by epoxy resin impregnation on the foam surface

The interfacial adhesion characteristics between foam cores and faces affect much the structural integrity of foam core sandwich structures. The peel strength between the face plate and the foam core is one of the appropriate parameters for the interfacial characteristics of sandwich structures and its peel energy is also measured for the interfacial characterization. The peel strength is the first peak force per unit width of bondline required to produce progressive separation, and the peel energy is the amount of energy per unit bonding area associated with a crack opening. In this study, to improve the peel strength between the foam core and the face plate of foam core sandwich beams, the surfaces of foam core sandwich beams were resin-impregnated. Then the peel strength as well as peel energy of resin impregnated polyurethane foam core sandwich beams were measured by the cleavage peel test and compared with those of the same sandwich beams without surface resin impregnation on the foam surface.     

复合材料泡沫夹层结构力学性能与试验方法

本文讨论纤维增强复合材料与聚合物泡沫组成的夹层结构的刚度、强度及弯曲性能试验方法;分析了复合材料面层的弹性常数、泡沫芯层的模量和夹层结构的刚度;阐述了夹层结构的应力分布和常见的5种破坏模式;对夹层结构的疲劳强度和冲击时的力学行为进行了探讨.     

Analytical method for determination of temperature-induced interfacial shear stress in foam-core composite sandwich materials

Composite sandwich materials with glass fibre-reinforced plastic (GFRP) skins and a foam core have been widely used in civil engineering. However, the interfacial delamination is the main failure mode in practice, especially at elevated temperatures. Temperature-induced interfacial shear stress can be generated because of the different coefficients of thermal expansion of GFRP skin and foam core, which can weaken the interfacial bond strength of sandwich materials. In this study, to investigate the distribution of temperature-induced interfacial strain, an analytical model was developed by using the infinitesimal method. In the meantime, a series of foam-core composite sandwich materials were tested via a kind of non-direct test method at different temperatures to validate the accuracy of the proposed analytical model. Finally, the comparison between experimental and analytical results demonstrates that the proposed analytical model can predict the interfacial strain distribution of sandwich structures at elevated temperatures.     

Comparison of foam core sandwich panel and through‐thickness polymer pin–reinforced foam core sandwich panel subject to indentation and flatwise compression loadings

Through‐thickness polymer pin–reinforced foam core sandwich (FCS) panels are new type of composite sandwich structure as the foam core of this structure was reinforced with cylindrical polymer pins, which also rigidly connect the face sheets. These sandwich panels are made of glass fiber–reinforced polyester face sheets and closed‐cell polyurethane foam core with cylindrical polymer pins produced during fabrication process. The indentation and compression behavior of these sandwich panels were compared with common traditional sandwich panel, and it has been found that by reinforcing the foam core with cylindrical polymer pins, the indentation strength, energy absorption, and compression strength of the sandwich panels were improved significantly. The effect of diameter of polymer pins on indentation and compression behavior of both sandwich panels was studied and results showed that the diameter of polymer pins had a large influence on the compression and indentation behavior of through‐thickness polymer pin–reinforced FCS panel, and the effect of adding polymer pins to FCS panel on indentation behavior is similar to the effect of increasing the thickness of face sheet. The effect of strain rate on indentation behavior of FCS panel and through‐thickness polymer pin–reinforced FCS panel were studied, and results showed that both types of composite sandwich panels are strain rate dependent structure as by increasing strain rate, the indentation properties and energy absorption properties of these structures are increased. POLYM. COMPOS., 37:612–619, 2016. © 2014 Society of Plastics Engineers     

不同增强方式下泡沫夹芯复合材料三点弯曲性能研究

研究了缝合及加强筋增强方式下泡沫夹芯复合材料的三点弯曲性能.采用万能试验机分别进行了缝合与未缝合碳纤维、玻璃纤维、玻碳混杂纤维泡沫夹芯复合材料的三点弯曲实验,分别得出各自的载荷-挠度曲线,再引入加强筋的方式进一步研究缝合碳纤维泡沫夹芯复合材料的弯曲性能.结果表明,玻碳混杂纤维泡沫夹芯复合材料较玻璃纤维泡沫夹心复合材料性...     

VARI成型不同处理方法泡沫夹芯复合材料工艺及性能研究

采取泡沫芯刻槽和泡沫芯导孔两种处理方法预制备泡沫芯材,采用VARI工艺成型泡沫夹芯复合材料,对复合材料进行无损检测,并对其成型效率、质量和力学性能进行研究。结果表明:刻槽和导孔处理可以有效地提高泡沫夹芯复合材料的成型效率,且其表面质量良好;三种泡沫夹芯复合材料泡沫与复合材料面板间均结合紧密,不存在贫胶、分层等缺陷;经刻槽处理后,泡沫夹芯复合材料的剥离强度有所下降,而弯曲强度和侧压强度略有上升;经导孔处理后,泡沫夹芯复合材料的剥离强度、弯曲强度和侧压强度均小幅下降。总的来看,不同处理工艺对VARI泡沫夹芯结构力学性能影响不大。     

A study on the compressive characteristics of co‐cured foam‐composite sandwich structures according to the crimp angle variations

A foam‐composite sandwich column composed of two‐ply carbon/epoxy fabric prepreg as a skin and PVC foam for a core material was investigated to determine the effect of crimp angle variations of the fabric prepreg on the compressive characteristics of the sandwich column. The crimp angle of the composite skin was observed and measured in terms of the forming pressure and the foam density as correlated with the foam deformation regimes. End compression tests for the foam‐composite sandwich columns were carried out to obtain the values of the compressive modulus and strength depending on the crimp angle variations. From the tests and observation results, it was found that the crimp angle and compressive strength were highly correlated; as the crimp angle increased, the compressive strength decreased as a large‐crimp angle caused the composite skin to fail due to simple microbuckling of the longitudinal tows. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers