玻璃纤维增强塑料蜂窝夹层结构材料热导率分析

玻璃纤维增强塑料蜂窝夹层结构材料是一种绝热材料,本文从蜂窝夹层结构的传热特点推导出热导率的理论计算公式,与实验值比较很符合,可供有关产品设计使用。     

Nomex蜂窝夹层复合材料的成型工艺研究

针对Nomex蜂窝填充双马树脂基复合材料夹层结构在固化成型过程中易出现的蜂窝芯边缘塌陷问题进行研究。通过采用不同的成型工艺方法,以及对共固化工艺参数进行调整,研制出相应的双马来酰亚胺树脂基碳纤维/蜂窝夹层结构层板,并且对夹层结构的力学性能、内部质量以及平面拉伸性能进行测试。在此基础上分析了成型压力参数对夹层结构质量的影响。相关工艺试验表明蜂窝芯塌陷的原因主要是固化过程中蜂窝芯边缘的滑移引起的蜂窝局部失稳,通过采取分步成型、蜂窝先胶接后修型的方法能够有效地解决Nomex蜂窝夹层结构填充双马树脂基复合材料结构成型过程中的蜂窝芯塌陷问题。     

复杂蜂窝夹层结构二次胶接校验精度影响因素研究

针对复杂蜂窝夹层结构的二次胶接工艺,通过采用不同校验压力、校验膜组合模式进行校验精度影响因素研究。结果表明:在较低压力下,校验外加压力对复杂蜂窝夹层结构的校验精度影响很小;校验膜组合方式对校验精度影响较大,板-板与板-芯胶接区域采用不同校验膜组合校验方式得到的校验结果优于板-板与板-芯胶接区域采用单一校验膜校验方式的结果。根据组合校验试验结果,建立了组合校验膜选择模型并对模型进行了验证。     

新型起圈织物增强蜂窝夹层板力学性能研究

复合材料夹层结构由于其优越的力学性能被广泛应用于当今航空工业,但是传统编织二维复合材料夹层板在厚度方向抗分层与抗剥离能力较差,起圈织物作为一种新型三维机织复合材料,可通过z方向预织的毛圈有效改善复合材料夹层板在厚度方向的力学性能。但目前国内对起圈织物增强夹层结构的力学性能研究较少。对起圈织物蜂窝夹层板的平拉力学性能进行研究,通过真空袋成型工艺制作了玻璃纤维起圈织物增强夹层板与传统玻璃纤维夹层板并完成平拉试验,获得了平拉载荷作用下的力-位移曲线与拉伸强度。试验结果表明起圈织物增强蜂窝夹层板具有更高的平拉模量与平拉强度。主要原因是固化时,起圈织物夹层板的蜂窝夹层中形成了环氧树脂胶柱体。胶柱体参与了芯材受力,增大了拉伸模量,同时嵌入胶柱体的毛圈也提高了起圈织物夹层板的平拉强度。由此可以得出结论:起圈织物可以有效提高蜂窝夹层板的平拉性能。最后就研究中出现的一些问题提出相应的改进方法与思路。     

低速冲击下铝蜂窝夹层板的动态响应研究

为了研究铝蜂窝夹层板在低速冲击下的动力学响应,通过有限元仿真软件ANSYS/LS-DYNA分析了半球头圆柱低速冲击铝蜂窝夹层板的损伤变形,建立了含蒙皮、蜂窝芯和胶层的铝蜂窝夹层板精细化仿真模型,通过与文献试验结果对比,验证了模型的准确性,并研究了铝蜂窝芯单元尺寸、高度以及金属、碳纤维增强复合材料(CFRP)两种蒙皮材料对蜂窝夹层板冲击响应的影响。结果表明:铝蜂窝芯单元尺寸越大,夹层板的刚度和稳定性越低;芯层高度对吸能的影响较小;胶层对吸能的影响不可忽略;相对于铝蒙皮,CFRP蒙皮铝蜂窝夹层板的吸能效果较好。     

一种玻纤/环氧-Nomex蜂窝夹层复合材料制备工艺与性能研究

以玻纤增强环氧预浸料、阻燃环氧结构胶膜和高密度Nomex蜂窝芯通过共固化工艺制备了夹层结构复合材料板,并对其进行了相关性能研究。通过分析预浸料蒙皮和胶膜中环氧树脂基体流变特性,以及研究共固化过程中的固化压力和升温制度对所制备夹层板力学性能的影响关系,制定出了适宜的复合材料成型工艺制度。结合上述研究成果,进一步对采用不同面重胶膜和铺层结构制备出的夹层板进行了性能测试,考核结果表明:胶膜用量的增加可以明显提高Nomex蜂窝夹层板的滚筒剥离强度和长梁弯曲性能,而对平面压缩性能影响较小,但会明显降低复合材料的整体阻燃和烟毒性能;此外,对称铺层结构的材料整体结构稳定性明显优于非对称铺层结构。     

基于高导热碳纤维复合材料的大尺寸高稳定桁架结构

正本发明公开了一种基于高导热碳纤维复合材料的大尺寸高稳定桁架结构,包括高导热碳纤维面板铝蜂窝夹层板、天线支撑桁架、高模量碳纤维面板铝蜂窝夹层板、铝面板铝蜂窝夹层板,天线支撑桁架为若干碳纤维多通接头与若干碳纤维杆件胶接装配而成的梯形立方体,天线支撑桁架下底面通过常温结构胶黏剂设有铝面板铝蜂窝夹     

树脂基复合材料蜂窝夹层结构修补技术研究

为了降低复合材料蜂窝夹层结构件制造成本及延长其使用寿命,修理技术是必不可缺的.本文主要针对面芯脱胶复合材料蜂窝夹层结构进行了平拉、侧压和疲劳试验,为修补提供依据;同时根据不同修理方法和材料体系对复合材料蜂窝夹层结构修理技术进行了研究.结果表明,复合材料蜂窝结构件受损后的修理问题基本可以得到有效地解决     

蜂窝拼接对夹层结构整体强度和刚度影响研究

蜂窝夹层结构广泛应用于航空飞行器上，但由于受到蜂窝尺寸的限制，在夹层结构大部件中，需要利用膨胀胶膜对蜂窝拼缝进行粘接，从而形成完整的蜂窝结构。对典型的铝蒙皮蜂窝夹层结构，研究蜂窝有拼缝以及对拼缝粘接后对夹层结构强度和刚度的影响，按照ASTM C393标准对试样进行四点弯曲试验，试验结果表明，典型的铝蒙皮蜂窝夹层结构蜂窝3mm拼缝以及对拼缝粘接后对夹层结构的整体强度和刚度无影响，利用有限元仿真进一步确认了夹层结构在四点弯曲情况下应力分布情况以及蜂窝芯子的具体破坏位置，从试验和仿真分析结果表明，典型夹层结构的蜂窝的3mm拼缝以及对拼缝用膨胀胶膜粘接对夹层结构强度和刚度无影响，并可基于试验验证的有限元模型对其它面板形式的夹层结构进行可靠的强度仿真分析。     

铝蜂窝复合材料的大面积粘接与应用

由铝蜂窝和铝合金面板粘接而成的蜂窝夹层结构具有质轻、比强度高、隔音、隔热、防潮和密封性好等特点，是一种很有价值的新型材料。本文所介绍的是大面积铝蜂窝夹层结构板的粘接成型与实际中的应用。     

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。     

玻璃钢蜂窝夹层结构接头试验分析及优化设计

玻璃钢蜂窝夹层结构的连接是很重要的,本文对笔者所试验过的三种接头进行强度理论分析,与试验结果很符合,并对此三种形式接头进行优化设计.     

共固化成型无人机用复合材料/蜂窝夹层结构面板的性能

针对无人机结构工程设计和工艺方案需要,通过试验比较几种预浸料在共固化成型工艺状态下制备的蜂窝夹层结构面板与在相同固化工艺条件下制备的层压板的力学性能,得出可直接采用共固化工艺制造无人机飞机机体结构的结论.性能结果显示,由所选择的适用于共固化工艺的预浸料所制备的面板与层压板试样的力学性能基本是相当的,但面板的层间剪切强度却明显比层压板的低.     

废旧纤维制备蜂窝夹层复合材料的导热性研究

利用半经验公式,对废旧纤维再生纺织品制备的蜂窝夹层复合材料的蜂窝高度、蜂格边长及蜂窝芯厚度分别与蜂窝结构导热性之间的关系进行理论预测。预测值与实验测定值进行比较,结果表明,预测值与实验测定值基本一致,所以可以通过数值计算的方法为废旧纤维再生纺织品蜂窝夹层复合材料的蜂窝芯子几何尺寸的设计提供参考。     

玻璃钢蜂窝夹层结构支撑点的设计

本文研究了某地面雷达天线罩采用的含有预埋件的玻璃钢蜂窝夹层结构支撑点的强度，把含有三种不同形式支撑点的蜂窝夹层结构试件的强度进行了对比，讨论了支撑点的形式对结构强度的影响。     

Deflection behaviors of polymer mortar sandwich panels reinforced with GFRP

This study prepared sandwich panel specimens composed of methyl methacrylate (MMA)‐modified polymer mortar at the core and reinforced with high‐tensile GFRP on both faces to propose a method to predict the deflection of polymer mortar sandwich panels under flexural load. Nine experimental specimens of different thickness at the core and face were prepared for the flexural load test to determine the moment‐deflection relationship, and the experimental results were compared with existing theoretical models. The comparison study revealed that the deflection behavior of the specimens in response to the variation in the thickness of the specimens at the core and face could be well predicted. Additionally, an analytical model, which revised a bilinear method, to explain the tension stiffening effect of the prepared sandwich panel specimens under the influence of flexural load is proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

High-velocity impact loading in honeycomb sandwich panels reinforced with polymer foam: a numerical approach study

The employment of lightweight structures is one of the most important goals in various industries. The lightweight sandwich panel is an excellent energy absorber and also a perfect way for decreasing the risk of impact. In this paper, a numerical study of high-velocity impact on honeycomb sandwich panels reinforced with polymer foam was performed. The results of numerical simulation are compared with the experimental findings. The numerical modeling of high-velocity penetration process was carried out using nonlinear explicit finite-element code, LS-DYNA. The aluminum honeycomb structure, unfilled honeycomb sandwich panel, and the sandwich panels filled with three types of polyurethane foam (foam 1: 56.94, foam 2: 108.65, and foam 3: 137.13 kg/m³) were investigated to demonstrate damage modes, ballistic limit velocity, absorbed energy, and specific energy absorption (SEA) capacity. The numerical ballistic limit velocity of sandwich panels, filled with three types of foam, was more than that of a bare honeycomb core and unfilled sandwich panel. In addition, the numerical results showed that the sandwich panel filled with the highest density foam could increase the strength of sandwich panel and the numerical specific energy absorption of this structure was 23% more than that of unfilled. Finally, the numerical results were in good agreement with experimental findings.

     

Experiments and numerical simulations of low‐velocity impact of sandwich composite panels

This article investigates the response of composite sandwich panel with Nomex honeycomb core subjected to low‐velocity impact and compression after impact (CAI) by using the methods of experiments and numerical simulations. Low‐velocity impact of sandwich panels at five energy levels is carried out to research the damage resistance and tolerance. A failure model based on Hashin failure criterion is implemented to model the intralaminar damage behavior of laminated plies in the numerical simulation. The cohesive zone model is used to simulate the delamination damage between adjacent laminated plies. The honeycomb core behavior is defined as an elastic–plastic material. Good agreements, in terms of contact‐force histories, damage shapes, and indentation depths of the sandwich panels, are observed between the experimental and numerical results. During CAI analysis, the damaged panels present a phenomenon of quick crack propagation from impact indentation location to each unloaded side after the structural strength reached. It is found that the in‐plane compressive strength of damaged sandwich panels is almost 25–35% reduction than that of undamaged panels. POLYM. COMPOS., 38:646–656, 2017. © 2015 Society of Plastics Engineers     

Shear properties of C/C-SiC sandwich structures

Carbon fiber reinforced carbon-silicon carbide (C/C-SiC) sandwich structures have been developed using the Liquid Silicon Infiltration process and the in situ joining method. They offer high mass-specific stiffness, low thermal expansion, and high environmental stability. Potential application areas are highly precise satellite structures, like optical benches. In this study, sandwich samples were manufactured using prepregs based on 2D carbon fibre fabrics and a phenolic resin precursor. Carbon fibre reinforced polymer preforms for folded and grid-cores, as well as for the skin panels were manufactured using autoclave technique. In the second step, the sandwich components were pyrolyzed, leading to C/C preforms. For the build-up of the sandwich samples, two skin panels were joined to a core structure and subsequently, the resulting C/C sandwich preform was siliconized. C/C-SiC sandwich samples were tested under shear load. Shear strength, modulus, and fracture strain were determined and compared to the results obtained by analytical calculation. The shear properties were dependent on the fiber orientation in the core structure as well as on the core type and orientation. The sandwich shear stiffness obtained in the tests was close to the expected theoretical values, calculated on the basis of the material properties and the core geometry.     

Shell91单元在复合材料蜂窝夹层结构分析中的应用

论述了蜂窝夹层结构的三种简化计算理论模型，介绍了通用有限元计算软件ANSYS中shell91单元的sandwich（夹芯）功能，通过计算与试验位移值结果的对比，相对误差小于5％，验证了该功能的工程实用性与易操作性。