超高分子量聚乙烯纤维增强中空蜂窝模压复合材料性能研究

为研制车船等壳体所用的轻质、高强复合板材,选用超高分子量聚乙烯(UHMWPE)短纤维纱,制备成单层经纬为120根/(10 cm)的平纹组织,采用多组经纱持续更替交织层的方法制成2L(1+0)型、4L(2+1)型、6L(3+2)型3种多层角联锁结构织物,采用扦插芯棒、模压成型方法制成菱形蜂窝状的热固性环氧树脂基中空板,并与2块真空吸液法制成的面板组成“三合一”复合板,同时测定了复合板材的结构特征及其平拉、平压和弯曲性能。结果表明:3种类型复合板的密度均远小于水的密度,其中6L(3+2)型最小,为0.48 g/cm³;复合板层数越多,环氧树脂越难渗透尤其是在中空板菱形交叉点处,复合板平拉、平压、抗弯曲强度则呈现递增,制成的6L(3+2)型复合板试样平压强度可达到1.03 MPa。     

梯度铝蜂窝夹芯板的力学行为

梯度分层铝合金蜂窝板是一种有效的吸能结构,本工作在梯度铝蜂窝结构的基础上根据梯度率的概念,通过改变蜂窝芯层的胞壁长度,设计了4种质量相同、梯度率不同的铝蜂窝夹芯结构。通过准静态压缩实验,并结合非线性有限元模拟准静态及冲击态下梯度铝蜂窝夹芯结构的变形情况及其力学性能,分析对比了相同质量下梯度铝蜂窝夹芯结构在准静态下的变形模式以及冲击载荷下分层均质蜂窝结构和不同梯度率的分层梯度蜂窝结构的动态响应和能量吸收特性。结果表明:在准静态压缩过程中,铝蜂窝梯度夹芯板的变形具有明显的局部化特征,蜂窝芯的变形为低密度优先变形直至密实,层级之间的密实化应变差随芯层密度的增大而逐渐减小;在高速冲击下,梯度蜂窝板并非严格按照准静态过程中逐级变形直至密实,而是在锤头冲击惯性及芯层密度的相互作用下整体发生的线弹性变形、弹性屈曲、塑性坍塌及密实化;另外,在本工作所设计的梯度率中,当梯度率为γ₁=0.0276时,梯度蜂窝夹芯板的吸能性达到最好,相较于同等质量下的均质蜂窝夹芯板,能量吸收提高了10.63%。     

高温合金蜂窝成形制造工艺及性能评价

目的 研究高温合金蜂窝成形工艺参数优化规律。方法 采用辊压成形、整形和点焊工艺制备高温合金蜂窝芯体，并对成形后的蜂窝芯体进行性能表征及失效分析。研究辊压成形工艺、整形工艺和点焊工艺参数，对采用最优工艺参数得到的高温合金蜂窝芯体样件分别进行压缩、剪切性能测试，对样件进行性能表征及失效分析，得出其最大压缩力、平面压缩强度以及失效方式。结果 选取30 t压力时，校形效果良好；当焊接电流为500 A，焊接时间为0.005 s时，焊点质量最好。结论 采用优化后的工艺参数制得的样件尺寸精度和质量较高，能够为高温合金蜂窝制造提供指导。     

Thermo-physical properties of Hastelloy X and Haynes 214 close to the melting range

ABSTRACT

The nickel-based superalloys Hastelloy X and Haynes 214 are widely used for honeycomb liners; however, thermo-physical properties at temperatures close to the melting range are poorly described in the literature. Based on the thermo-physical properties, endothermic effects between 550°C and 650°C have been observed that develop due to the formation of the short-range order in both alloys and in Haynes 214, in addition to the short-range order, an increase in the specific heat capacity due to the γ′-precipitation up to 950° was detected. At low and intermediate temperatures, the Hastelloy X is significantly better suited than the Haynes 214. At high temperatures the Haynes 214 is superior to the Hastelloy X due to the dissolution of the γ′-phase.     

Structural dimension optimization and mechanical response analysis of fabricated honeycomb plastic pavement slab

Because of favorable mechanical properties, deformation resistance and being conducive to environmental protection, honeycomb fabricated plastic pavement slabs are highly recommended these years. At present, most studies focus on the performance of plastic materials, however, the dimension optimization of fabricated plastic pavement slab is rarely mentioned. In this paper, an optimized geometry of the honeycomb pavement slab was determined through finite element analysis. Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored. Several dimension factors were taken into consideration including the side length, rib thickness, the thickness of both top and bottom slabs of honeycomb structure and the length, the width and the thickness of the fabricated plastic slab. The results showed that honeycomb pavement slab with 6 cm bottom slab, 12 cm top slab,18 cm side length and 6 cm rib thickness is recommended, additionally, an external dimension of 4 m × 4 m × 0.45 m is suggested. Then, the mechanical responses of this optimized fabricated plastic slab were further investigated. Significance of different influencing factors, including wheel load, elastic modulus of plastic material, base layer thickness, soil foundation modulus and base layer modulus were ranked.     

Effect of electrode spacing on the performance of microbial fuel cells with a honeycomb flow straightener

Microbial fuel cells (MFCs) are bioelectrochemical transducers that can be used to produce electrical power under the activity of microbes during the wastewater treatment processes. In the present study, the electrode spacing was considered as a parameter to investigate the influence on the performance of MFCs. The electrode spacing was defined as the distance of the anode electrode plate to the polymer exchange membrane in the MFCs. Three values were set at 0.0, 3.0, and 6.0 cm, respectively. In addition, a flow device, like a honeycomb type flow straightener, was introduced and implemented in the anode chamber for creating a uniform flow. The inner diameter of the honeycomb was 0.7 cm. Results showed that a higher limiting current density with 4108.7 mA/m² and a lower resistance with 2.51 Ω can be found in the case of the 0.0 cm electrode spacing. These results also indicated that the shorter electrode spacing with flow straightener devices would improve the performance of MFCs, leading to lower internal resistance and higher power density. In addition, the scanning electron microscopy was employed to analyze the biofilm thickness for MFCs with different electrode spacing. It was also found that the biofilm thickness with 0 cm electrode spacing was larger than the other two cases, leading to a lower internal resistance in the MFCs.     

相对湿度和开孔对纸蜂窝芯层抗压强度的影响

对无孔、开孔蜂窝芯纸条和5种纸蜂窝芯层进行静态压缩实验,研究了相对湿度和开孔(圆孔直径、圆孔数量)对蜂窝芯纸条纵向和横向环压强度以及纸蜂窝芯层抗压强度的影响规律,采用多元线性回归分析法和SPSS软件评估了相对湿度和圆孔直径对蜂窝芯纸条纵向和横向环压强度的影响,探讨了长度缺陷率与环压强度系数之间的经验关系。实验结果表明,无孔和开孔蜂窝芯纸条的纵向环压强度是横向环压强度的1.4~1.5倍;蜂窝芯纸条纵向和横向环压强度以及纸蜂窝芯层的抗压强度都随着相对湿度、圆孔直径和圆孔数量的增加而降低,且双孔蜂窝芯纸条的纵向环压强度和双孔纸蜂窝芯层的抗压强度更易受相对湿度的影响;在相对湿度和开孔的综合影响下,纸蜂窝芯层适合开圆孔直径为2 mm或3 mm的单孔。     

浅谈桥涵混凝土表面蜂窝麻面的防治措施

结合福山立交至福山镇公路改建工程混凝土桥涵的施工过程,从多方面分析桥涵混凝土表面产生蜂窝麻面的原因,并提出防治措施,从而避免蜂窝麻面的产生,提高桥涵的外观质量。     

新型玻璃钢蜂窝夹层结构模板的试验研究

本文提出以玻璃钢板、纸蜂窝及适当玻璃钢管制成的一种新型建筑模板。新型夹层模板的荷栽试验结果表明：在芯层中加入玻璃纤维管能有效控制夹层结构的剪切变形，提高面板材料的利用率。该种新型模板的变形及承栽能力均满足施工要求。在试验研究的基础上，本文给出新型夹层结构的应力和挠度计算公式。