低速冲击后复合材料蜂窝夹芯板的拉伸特性

对含低速冲击损伤的蜂窝夹芯板试件进行了拉伸试验, 用X 光技术、热揭层技术和外观检测等对拉伸破坏过程进行了研究, 分析了剩余拉伸强度与冲击能量的关系。结果表明: 拉伸过程中, 四种破坏形式同时存在且相互作用; 冲击损伤严重影响了蜂窝夹芯板的抗拉能力。      

Intensity of Local Effects at the Core Junctions in Sandwich Panels

Local effects that occur in the vicinity of junctions between different cores in sandwich panels subjected to the in-plane axial force and bending moment are considered. These local effects manifest themselves in a rise of locally induced bending normal stresses in the sandwich faces and shear and normal stresses in the cores in the near vicinity of the core junctions. Intensity of the local effects is measured experimentally for a representative sandwich beam subjected to both types of loadings. The numerical simulations are performed using Finite Element Analysis, and they reveal significant rates of stress concentrations in the faces and cores adjacent to the core junctions. The intensity of the local effects is dependable on the geometry and elastic properties of the sandwich faces and a degree of dissimilarity of elastic properties of the adjoined cores.     

整体中空夹层复合材料低速冲击损伤及剩余强度实验研究

简要论述了整体中空夹层复合材料低速冲击及冲击后剩余强度的研究情况,选取了三种不同规格的试件进行了不同能量下的低速冲击试验和冲击后的拉伸,压缩强度试验,得到不同能量下材料的损伤情况和强度变化曲线。实验结果与国外相关文献进行了对比,与文献结果具有一致的变化规律,对整体中空夹层复合材料的运用及推广有一定得参考意义。     

高速冲击载荷作用下钎焊蜂窝夹层板动态响应

目的 以钎焊高温合金蜂窝夹层板为研究对象,分析其在弹丸高速冲击作用下的力学性能。方法 采用轻气炮冲击加载试验结合有限元模拟,对蜂窝夹层板开展不同冲击强度下的动态响应和失效研究。开展含高速冲击损伤的蜂窝夹层板侧压试验,研究损伤模式对剩余强度的影响。结果 冲击强度对夹层板的失效过程和失效模式有着明显的影响,当冲击条件不足以使得迎弹面发生侵彻时,夹层板失效为表面压痕损伤;随着冲击强度的提高,出现不同程度的局部芯层压缩;当冲击强度大于临界值时,迎/背弹面陆续被侵彻,夹层板出现侵入损伤及贯穿损伤。结论 高速冲击损伤使得蜂窝夹层板的侧压失效模式,由理想塑性屈曲转变为局部失稳,侧压极限载荷大幅降低。     

泡沫夹层复合材料耐水性能研究进展

泡沫夹层复合材料作为一种新型轻质高强材料,目前越来越受到航天、航海及能源等领域的重视,但其应用大部分仍局限于次级结构,主要是由于其可靠性评价未得到广泛深入研究。概述了其吸水性能、吸水后静态和动态力学性能及断裂韧性变化规律,最后提出了防水措施。     

Damage Modeling of Notched Graphite/Epoxy Sandwich Panels in Compression

Open-hole honeycomb sandwich panels with woven graphite/epoxy facesheets and Nomex cores were tested uniaxially in compression to characterize their damage tolerance. A plain weave T-300 graphite fiber fabric was used for the facesheets in two stacking sequences: [45/0₂] and [0₃]. Observations of macroscopic sub-critical damage behavior were different in the two material systems. Linear damage zones (LDZ), consisting of fiber micro-buckles and extensive delamination, were typically observed in the [0₃] material. The [45/0₂] material exhibited a delamination/bulge zone (DBZ), which consisted of an out-of-plane curved deformation of the outer 45° ply accompanied by a delamination from the interior 0° plies. Modeling of these apparently distinct failure modes, and comparison to experimental data, revealed that the only mode representative of damage tolerant behavior is linear damage zone formation and propagation for both material systems, and that the delamination/bulge behavior is a secondary phenomenon.     

缝合泡沫夹层复合材料低速冲击数值模拟及实验

在ABAQUS分析平台中建立了缝合泡沫夹层复合材料在低速冲击下的动力学有限元模型,采用杆单元模拟缝线树脂柱的作用,基于Hashin破坏准则模拟层板面内损伤,通过各向同性硬化本构模型利用等效塑性变形模拟泡沫夹芯损伤演化。针对相同铺层的缝合和未缝合泡沫夹层结构,模拟了相同冲击能量下的低速冲击响应过程及面板、泡沫的损伤情况,数值结果与实验结果吻合较好,证明了该方法的有效性和准确性。研究结果表明,在低速冲击下,泡沫夹层结构引入缝线后虽然降低了泡沫缓冲吸能的作用,使得面板表面受到较大的冲击破坏,但增强了整体刚度,增大了面板抵抗弯曲变形的能力,减小了内部面板的损伤,使其在改善复合材料面板易分层缺陷的同时还依然拥有优良的面内性能。     

Laser Bending of Aluminum Foam Sandwich Panels

Aluminum foam sandwich panels were laser bent by means of a diode laser. Two panels different in thickness were used in bending tests; the effect of the main process parameters (laser power and scan velocity) on the bending efficiency was investigated as well as the contribution of the panel skin, and the protective gas. As a result, a very good formability was observed for the laser processed panels.     

复合材料蜂窝夹层板结构的多工况优化设计研究

以复合材料蜂窝夹层板结构作为研究对象,建立了多工况优化模型,对众多的材料设计变量进行必要的取舍,通过优化分析确定复合材料蜂窝夹层板面板各分层的厚度以及蜂窝芯层的厚度等,使结构满足相应的频率约束、屈曲约束,以及强度约束、位移约束和尺寸限制等,同时达到结构的重量最轻。采用序列二次规划法对某卫星的承力筒结构进行了优化设计,优化结果表明:在满足其振动特性以及静力学特性的条件下,复合材料蜂窝承力筒的各面板层厚度以及蜂窝芯层的厚度均有所减小,减重效果显著,较好地实现了复合材料蜂窝夹层板结构的多工况优化设计。     

V型折叠式夹层板横向压皱吸能特性研究

金属夹层板具有优越的力学性能,良好的吸能特性可用于船舶耐撞、抗爆防护结构设计。以V型折叠式夹芯结构为研究对象,通过试验分析夹芯层结构变形模式、压皱力历程曲线等,得到了夹芯层结构横向压皱力学性能,采用有限元软件Abaqus对其在横向受压时的力学行为进行数值仿真分析,分析结构压皱动态渐进屈曲过程、变形模式、吸能效率、平均压皱强度等。对比分析表明,V型夹芯层结构在横向压皱载荷下发生屈曲、褶皱变形模式,变形模式决定了压皱力学行为及其性能,其中单元变形模式I的吸能效率较高。采用合理的模型化技术得到的有限元计算结果与试验结果两者吻合较好,验证了有限元数值仿真的计算精度。     

泡沫铝三明治板的研究与应用进展

泡沫铝三明治板(Aluminum foam sandwich,AFS)是基于泡沫铝材料开发的一类材料-结构一体化的先进多孔复合结构。AFS是交通运输、建筑以及航空航天等装备结构轻量化的重要材料,具有广阔的应用前景。概述了AFS的几类制备技术的基本原理和研究现状,着重分析了复合预制体制备、合金成分、AFS发泡成型工艺等关键环节中存在的理论和技术难点。介绍了AFS作为结构材料和功能材料的典型应用案例;最后总结提出了AFS材料研究和工程化技术开发的关键点与突破途径。     

航天用蜂窝夹层板传热特性的研究进展

传热特性是蜂窝夹层板的一个主要性能指标。该研究结合空间应用的特殊性,介绍了蜂窝夹层板传热性能的研究方法,主要包括Swann-Pittman类方法、有限体积法、宏观热阻法、热叠层理论等效方法、有限元方法、净热流法和试验分析。讨论了它们各自存在的问题。并提出了需要进一步完善的方法:瞬态特性求解方法及不同方向/多变量的试验研究。     

Fabrication of Open-cell Al Foam Core Sandwich by Vibration Aided Liquid Phase Bonding Method and Its Mechanical Properties

The open-cell Al foam core sandwiches(AFCSs) were successfully fabricated by using a specially designed Zn-Al-Cu based filler alloy via vibration aided liquid phase bonding method.The effects of the vibration on the bonding seam were investigated and the bonding strength between Al foam core and solid Al alloy face sheet was tested by shearing tests.The results show that vibration can significantly improve the quality of the bonding and the shearing strength of the bonding seam,which implies that this joini...     

含泡沫铝芯的复合板弯曲疲劳行为的研究

应用表面位移原位分析技术对由泡沫金属铝芯和金属面板组成的三层复合板在循环弯曲载荷条件下的损伤行为进行了观察和研究。循环弯曲载荷条件下复合板失效的基本方式是表面凹陷（Indentation，ID）和泡沫铝内芯切断（Coreshear，CS）。凹陷型失效是与加载压头接触的复合板表面局部压缩密切相关，该处沿垂直方向的压缩应变最大。内芯切断型失效是泡沫铝内芯中切应变最大的区域发生的剪切破坏。在疲劳应力比R=0时，复合板凹陷型失效的疲劳极限高于内芯切断型失效的疲劳极限。     

粘接界面泡沫铝夹芯板的三点弯曲失效数值模拟

对粘接界面泡沫铝夹芯板三点弯曲载荷下的变形特性进行了实验和数值模拟方面的研究。基于有限元软件ABAQUS建立了泡沫铝夹芯板的三维有限元模型,应用内聚力模型对三点弯曲过程中典型的破坏模式——面板与芯层的界面脱粘给予了合理的模拟,模拟所得的结果与实验结果比较吻合。并在此基础上分析了面板和芯层厚度对夹芯板承载能力和吸收能量能力的影响。结果表明,增加芯层的厚度能够更大程度上提高泡沫铝夹芯板的承载能力和吸收能量的能力。     

Z 向增强泡沫夹芯复合材料冲击损伤及冲击后压缩性能

基于热压罐成型工艺, 选择了树脂柱Z向增强泡沫芯材、碳纤维Z向增强泡沫芯材、Kevlar纤维缝纫增强泡沫芯材3种Z向增强复合材料结构, 对夹芯结构进行了低速冲击损伤和冲击后压缩(CAI)性能研究, 考察了不同Z向增强方式对冲击损伤面积和破坏模式的影响。结果表明, Z向增强对泡沫芯材产生了初始损伤, 其冲击后损伤面积大于未增强泡沫夹芯结构; 但Z向增强改变了夹芯结构的压缩破坏机制。通过选用合适的Z向增强材料和Z向增强参数, 能够提高夹芯结构的压缩强度和CAI强度。其中当增强材料为碳纤维, 增强参数为10 mm×10 mm时, 压缩强度提高了13%, CAI强度提高超过40%。     

Fabrication and Testing of Carbon Fiber Reinforced Truss Core Sandwich Panels

Truss core sandwich panels reinforced by carbon fibers were assembled with bonded laminate facesheets and carbon fiber reinforced truss cores.The top and bottom facesheets were interconnected with truss cores.Both ends of the truss cores were embedded into four layers of top and bottom facesheets.The mechanical properties of truss core sandwich panels were then investigated under out-of-plane and in-plane compression loadings to reveal the failure mechanisms of sandwich panels.Experimental results indicated...     

Effects of core machining configuration on the debonding toughness of foam core sandwich panels

Core machining is often applied to improve the formativeness of foam core and the manufacturing effectiveness of sandwich panels. This paper investigates the effects of core machining configuration on the interfacial debonding toughness of foam core sandwich panels fabricated by vacuum-assisted resin transfer molding process. Several machining configurations are conducted to foam core, and skin–core debonding toughness of fabricated sandwich panels is evaluated using double-cantilever-beam tests. The sandwich panels with core cuts exhibited higher apparent fracture toughness than the panels without core cut, specifically in the case of perforated core. The relationship between core machining configuration and measured fracture toughness is discussed based on the experimental observations and the numerical analyses of energy release rates.     

等腰梯形蜂窝芯玻璃钢夹芯板的面外压缩性能EI北大核心CSCD

利用材料试验机对玻璃钢(FRP)夹芯板面外压缩性能进行实验测试与模拟研究。结果表明:夹芯板面外压缩变形可分为弹性变形与断裂两个阶段。蜂窝芯中part 2胞壁厚度t1与part 2高度h比值t1/h较大时,夹芯板以屈服方式变形;t1/h较小时,夹芯板以屈曲方式变形。蜂窝芯中part 2为夹芯板主要承载构件,蜂窝芯中part 1与part 3对part 2起到固支作用,面板对蜂窝芯起到固支作用。蜂窝芯中part 2胞壁厚度为夹芯板面外压缩抗压强度影响的主要因素,蜂窝芯胞壁边长影响次之,而蜂窝芯中part 1,part 3与面板厚度的影响较小。夹芯板总高度一定时,随着蜂窝芯层数增加,夹芯板抗压强度逐渐增大。     

复合材料蜂窝夹芯板低速冲击损伤研究

本文对蜂窝夹芯板试件进行了低速冲击试验, 然后用X 光技术、热揭层技术、断面显微技术和外观检测等对冲击后板的损伤进行了较为全面的研究, 讨论了表面布的作用, 分析了外观损伤、面板损伤、蜂窝损伤等与冲击能量的关系。