Mechanical property of cylindrical sandwich shell with gradient core of entangled wire mesh

To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components,the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed in this paper.Firstly,the gradient cores of entangled wire mesh in the axial and radial directions were prepared by using an in-house Numerical Control weaving machine,and the metallurgical connection between skin sheets and the gradient core was performed using vacuum brazing.Secondly,to investigate the mechanical properties of cylindrical sandwich shells with axial or radial gradient cores,quasi-static and dynamic mechanical experiments were carried out.The primary evaluations of mechanical properties include secant stiffness,natural frequency,Specific Energy Absorption(SEA),vibration acceleration level,and so on.The results suggest that the vibration-attenuation performance of the sandwich shell is remarkable when the high-density core layer is at the end of the shell or abuts the inner skin.The axial gradient material has almost no influence on the vibration frequencies of the shell,whereas the vibration frequencies increase dramatically when the high-density core layer approaches the skin.Moreover,compared to the conventional sandwich shells,the proposed functional grading cylindrical sandwich shell exhibits more potential in mass reduction,stiffness designing,and energy dissipation.

Mass transfer enhancement and hydrodynamic performance with wire mesh coupling solid particles in bubble column reactor

It is of vital significance to investigate mass transfer enhancements for chemical engineering processes.This work focuses on investigating the coupling influence of embedding wire mesh and adding solid particles on bubble motion and gas-liquid mass transfer process in a bubble column.Particle image velocimetry(PIV)technology was employed to analyze the flow field and bubble motion behavior,and dynamic oxygen absorption technology was used to measure the gas-liquid volumetric mass transfer coefficient(kLa).The effect of embedding wire mesh,adding solid particles,and wire mesh coupling solid particles on the flow characteristic and kLa were analyzed and compared.The results show that the gas-liquid interface area increases by 33%-72%when using the wire mesh coupling solid particles strategy compared to the gas-liquid two-phase flow,which is superior to the other two strengthening methods.Compared with the system without reinforcement,kLa in the bubble column increased by 0.5-1.8 times with wire mesh coupling solid particles method,which is higher than the sum of kLa increases with inserting wire mesh and adding particles,and the coupling reinforcement mechanism for affecting gas-liquid mass transfer process was discussed to provide a new idea for enhancing gas-liquid mass transfer.

Effect of wire mesh interlayer in explosive cladding of dissimilar grade aluminum plates

Explosive cladding of Al 5052–Al 1100 plate, interfaced with a stainless steel wire mesh interlayer, is attempted. Loading ratio and standoff distance were varied. An increase in loading ratio (R) and standoff distance (S) enhances the plate velocity (Vp), dynamic bend angle (β) and pressure developed (P). The interface morphology of the explosive clads confirms strong metallurgical bond between the wire mesh and aluminum plates. Further, a smooth transition from straight to undulating interlayered topography is witnessed. The introduction of a wire mesh, as interlayer, leads to an improvement in mechanical strength with a slender reduction in overall corrosion resistance of the “explosive clads”.

Effect of silicon carbide and wire-mesh reinforcements in dissimilar grade aluminium explosive clad composites

Aluminium composites are inevitable in the manufacture of aircraft structural elements owing to less weight,superior corrosion resistance and higher specific properties.These composites reduce the weight of the aircraft,improve the fuel efficiency and enhance the maintenance duration.This study proposes the development of dissimilar grade aluminium(aluminium 1100-aluminium 5052)composites with different reinforcement’s viz.,stainless steel wire-mesh,silicon carbide(SiC)powders and SiC powder interspersed wire-mesh,by explosive cladding technique.Wire-mesh enhances the friction and restricts the movement of flyer plate to craft a defect free clad,while SiC particles form a band on the interface.Highest strength is obtained when SiC powder interspersed wire mesh is employed as reinforcement.The dissimilar aluminium explosive clad with SiC particle reinforcement results in lower strength,which is higher than that of the weaker parent alloy and that of the conventional dissimilar aluminium explosive clads without any reinforcement.

Performance evaluation of the incorporation of different wire meshes in between perforated current collectors and membrane electrode assembly on the Passive Direct methanol fuel cell

Passive Direct methanol fuel cells(DMFC)are more suitable for charging small capacity electronic devices.In passive DMFC,the fuel and oxidant are supplied by diffusion and natural convection process on the anode and cathode sides respectively.Current collectors(CC)play a vital importance in fuel cell performance.This paper presents the combined impact of perforated and wire mesh current collectors(WMCC)on passive DMFC performance.Three types of open ratios of perforated current collectors(PCC),such as 45.40%,55.40%and 63.40%and two types of wire mesh current collectors with open ratios of 38.70%and 45.40%were chosen for the experimental work.A combination of TaguchiL9 rule is considered.A combination of three PCC and two WMCC on both anode and cathode was used.Methanol concentration was varied from 1 mol·L^(-1)-5 mol·L^(-1)for nine combinations of PCC and WMCC.From the experimental results,it is noticed that the combination of PCC and WMCC with an open ratio of 55.40%and 38.70%incorporated passive DMFC produced peak power density at 5 mol·L^(-1)of methanol concentration.The passive DMFC performance was evaluated in terms of maximum power density and maximum current density.The combined current collectors of PCC and WMCC open ratios of 55.40%+38.70%have more stable voltage than single PCC of open ratio 63.40%at 4 mol·L^(-1)of methanol concentration.

Anping County Shangchen Wiremesh Products CO.,LTD.

Anping County Shangchen Wiremesh Products CO.,LTD. is found in 2010, it is a modem enterprise which set research and development,foreign trade into a whole. The head office is located in “Hometon of Wire Mesh in China” Anping County is famous as hometown of wire mesh. Anping County Shangchen Wiremesh Products CO.,LTD. main products and sales: Gabion Mesh, Wire Mesh Fence, Perforated Metal, Welded Wire Mesh, Filter Mesh, Window Screen, Plastic Net, Filter Cartridge, Metal Basket, Barbecue Wire Mesh, Metal Cage, Fiberglass Mesh, Steel Grating, Metal Wire. Our products are widely used in industry, agriculture, cultivation, construction, transport and mining.By now we have already established friendly business relations with more than 80 countries from Southeast Asia, Europe, America, Middle East,Africa, and the sales amount and customers quadruple annually.

INVESTIGATION OF PULSED-WIRE TECHNIQUE FOR WALL PARAMETERS MEASUREMENT IN SEPARATED FLOWS

A pulsed-wire wall probe measurement system was developed in this paper,which can be used for measuring wall Parameters in separated flow- The operating princi-ple was described and the way of probe calibration was given. Wall parameters of back-ward-facing and forward-facing step flow were measured,and the wall nows structure andcharacters were revealed.

Estimate the Ventilation Effect from Wire Mesh Screen Assisted Solar Chimney

In 1750s European houses, chimneys are used to remove smoke and dust particle from the fire place to the ambient. At present the applications of chimneys are extended for house ventilation, which is known as solar chimney assisted ventilation system. In this paper, the effect of wire mesh screen on chimney assisted ventilation system is studied and presented. Natural draft chimney integrated with solar heating system that is known as solar chimney, can be used for building ventilation. Number of research works had been conducted on different types of solar chimney to enhance the building ventilation performance. In this study a solar chimney model is designed and modified with wire mesh screens. An electric heating system is installed in the models to replace the solar absorber in the solar chimney. The airflow rates and the exit air temperatures are also measured and compared for normal chimney and modified chimneys under different heat loads. The performances of the chimneys are evaluated to determine the effects of wire mesh screen on the solar chimney. Experimental results indicated the solar chimney model with 0.64 mm × 0.64 mm pore size wire mesh screen at the exit is able to enhance velocity and the exit air temperature are about 54% and 41%, respectively. It has been concluded that the wire mesh screen has significant effect of model solar chimney and is able to enhance the performance.

基于动网格技术的CMT-WAAM熔池温度场与流场数值模拟

针对基于冷金属过渡(CMT)技术的镁合金摆动电弧增材制造(WAAM)过程,采用流体体积(VOF)法和动网格(DM)技术建立了分别考虑熔滴和熔池受力情况的三维瞬态数值模型,研究了熔滴过渡和熔池流动过程中的温度场和速度场变化.结果表明,相应试验结果验证了所建立数值模型的有效性,熔池和熔滴尺寸参数模拟的误差均在10%之内.在CMT-WAAM开始阶段,基板表面和焊丝在电弧热作用下熔化分别形成熔池和熔滴.在焊丝向熔池送进过程中,熔滴不断长大,并在表面张力作用下长成球形.熔滴金属的热量主要通过热传导的形式向熔池传递,熔池最高温度随着熔滴金属的过渡而升高,熔池最高温度可达2100.0K;随着焊丝的回抽,熔池最高温度降低至1763.6K.随着焊丝向熔池送进,熔滴的最大速度从1.87 m/s逐渐减小到1.07 m/s,而熔池的最大速度仅为0.87 m/s.当熔滴金属前端与熔池发生接触后,液态金属的最大速度可达到4.21 m/s;随着焊丝的机械回抽,液态金属的最大速度在1.69~4.90 m/s范围内波动.当熔滴与熔池接触发生短路时,熔滴金属从熔池表面流向熔池底部和熔池两侧,增强了对熔池底部和熔池两侧的搅拌作用,使得熔池体积增加;当熔滴从焊丝端部脱离后,熔池中液态金属从熔池底部流向熔池表面和熔池两侧,熔池温度和流体速度随之降低,从而减缓了熔池体积的增加.此外,熔池自由表面在摆动电弧作用下呈现波浪式变形.

Mesh网络中实用有效的多信道分配方法

多信道多接口可以明显提高Mesh网络的吞吐量,然而已有的多信道分配算法和协议基本上都没有考虑无线信道的隔离度,这样便造成了路径间干扰。提出了一种基于信道隔离度的启发式多信道分配算法(CSCA),有效地减少了路径间干扰。所构建的森林拓扑一方面方便了信道分配,另一方面也改善了流量均衡。模拟实验结果表明,CSCA算法有效地降低了Mesh网络中的干扰,提高了网络吞吐量。

玻璃纤维-钢丝网增强复合材料拉伸性能研究

采用真空辅助树脂灌注成型(VARI)工艺,双向编织玻璃纤维和矩形不锈钢钢丝网制备了10种不同丝径和孔间距的复合材料试件。研究了不同钢丝网参数对复合材料拉伸性能的影响,并结合数字图像相关技术揭示了其失效机制。研究结果表明,材料的变形在拉伸初始阶段受到钢丝网的约束,随着荷载的增加,试件被钢丝网分割为更多的应变单元,最后钢丝网和纤维发生相对滑移,一侧纤维发生断裂并向另一侧迅速撕裂开从而导致试件破坏,试件的失效全部为脆性失效。引入钢丝网显著提高了玻璃纤维-钢丝网增强复合材料的刚度、峰值荷载和极限应变等参数,相较于无钢丝网试件,极限荷载最大提升了61.18%,最大位移提升了37.17%;此外钢丝网在试件内表现出了良好的延性。研究结果为复合材料加固的工程应用提供了一定的参考。

WEDM oriented micro gear design and mesh simulation

For the design of gears manufactured with wire electrical discharge machining （WEDM） technology, determination of the primary gear parameters is discussed considering the characteristics of the machining method. Some constraint conditions on gear parameters are abnegated, which makes micro gear design more flexible. Based on gear mesh theory, the algorithm of generating gear tooth profiles is studied, which includes involute and non-involute curve segments. The phenomena of tooth profile interferences during gear mesh are analyzed, and a gear mesh simulation algorithm is designed. Based on ACIS, the WEDM oriented software for the design and mesh simulation of micro gears is developed, by which the modeling, mesh simulation and interference check can be implemented. An experiment is carried out to design and manufacture a pair of micro involute gears, and the proposed method is proved feasible.

基于无线Mesh接入服务技术的校园网设计与实现

无线Mesh网简称WMN,是一种新型的无线通信网络;这是一种高容量、高速率、多跳的分布式宽带无线网络.以某体育学院校园网工程为背景,对原有校园网进行分析,提出了全新的整体规划,包括各层交换机和路由器的配置、无线接入的配置等;设计中采用三层交换结构,即接入层、汇聚层和核心层,在各个层上采用相应的配置策略;新的设计提高了校园网数据交换速率和整体性能.

无线mesh网络中学习资源的最优复制策略

以移动学习中的课件点播为应用背景,提出了以连接代价最小的学习资源复制策略,将选择的最优资源预先复制到无线mesh网络(WMNs)中的骨干节点上,当学习者需要某一资源时,可通过Peer-to-Peer(P2P)方式,从最近的节点中获得所需学习资源,从而提高用户的连接速度和播放质量,同时缓解WMNs中网关节点的负载压力.针对所求问题是一个特殊的多维0-1背包问题,提出了一种改进的分布式遗传算法对问题进行了求解.仿真结果说明了改进算法的优越性.

船用洗涤塔除尘效率试验研究

针对船舶双燃料主机的废气除尘要求,综合成本、布置以及除尘效率需求,使用填料洗涤塔更加便捷。本文研究基于填料洗涤塔除尘效率的试验装置设计,通过引主机后的废气进入洗涤塔,使用离心泵抽取循环柜中的淡水在板式热交换器中进行换热后通过喷嘴喷淋至塔内,填料塔内设置规整填料、螺旋喷嘴喷淋、除雾器,使用滤纸烟度计测量该试验装置中洗涤塔在主机燃油和燃气模式下的除尘效率,设计两种不同的除尘结构试验装置,并在此基础上进行试验验证和对比,验证在不同喷淋水量、不同主机燃烧模式和不同除雾型式下的洗涤塔除尘效率,从而得到在燃油模式下更加适合应用的丝网除尘结构和适合的喷淋水量。

无线Mesh网络中的骨干网络部署的优化

在满足用户需求情况下,优化无线Mesh网络中接入点(TAPs)放置以及布线线路以减小布线成本。首先,把该问题中的布线问题模型化为欧氏空间中准组Steiner树问题。解决传统的组Steiner树问题的算法在该问题上并不适用。其次,针对该问题特有的特征给出了一种近似算法。最后,为了达到最小化网络布线的成本的目的,在布线的基础上使用线性规划达到最小化TAPs数目。模拟实验的结果表明,该方法能够显著降低布线成本。优化方法对于无线Mesh网络的骨干网络的部署具有重要指导意义。

Experimental testing of low-energy rockfall catch fence meshes

Flexible catch fences are widely used to protect infrastructure like railways, roads and buildings from rockfall damage. The wire meshes are the most critical components for catch fences as they dissipate most of the impact energy. Understanding their mechanical response is crucial for a catch fence design. This paper presents a new method for testing the wire meshes under rock impact. Wire meshes with different lengths can be used and the supporting cables can be readily installed in the tests. It is found that a smaller boulder causes more deformation localisation in the mesh. Longer mesh length makes the fence more flexible. Under the same impact condition, the longer mesh deforms more along the impact direction and shrinks more laterally. Supporting cables can reduce the lateral shrinkage of the mesh effectively. Most of the impact energy is dissipated by stretching of the wires.Wire breakage has not been observed.

Corrosion considerations in the capacity of welded wire mesh

Ground control in underground mines employs rock reinforcement and surface support to maintain the integrity of excavations for their anticipated working life.The performance of a ground support system,however,is more complex and relies on effective load distribution between reinforcement and surface support elements.Typically,failure of the ground support system is along its weakest link,often the surface support.Consequently,the degradation of any ground support element over time will compromise the structural integrity of the ground support system.Degradation of ground support can be due to multiple factors.This paper focuses on the role of corrosion in the long-term performance of mesh.It presents a comprehensive methodology for quantifying the impact of degradation on bolted welded wire mesh over time.This is an important aspect,as the mesh is often the first element that fails in a ground support system.This paper combines information from extensive field and laboratory studies on mesh corrosion with calibrated numerical models to capture the long-term performance of different bolting patterns under a range of corrosion environments.A series of three-dimensional(3D)distinct element models(DEM)were constructed to quantify the impact of different corrosion rate scenarios on the loading capacity,displacement,and failure mechanisms of bolted welded wire mesh in diamond and square bolting patterns.This work can contribute to the management of long-term hazards associated with corrosion of mesh in corrosive environments under non-seismic mining conditions.

Performance of Flexible Warp Knitting Metal Mesh with Notch

Three different kinds of notch involving single edge notch （ SEN）, double edge notch （ DEN ） and central notch （ CEN ） were preset in flexible warp knitting metal mesh, and the tensile properties of notch samples were tested. Three kinds of notch samples＇ sensitivity were investigated through different notch lengths. Then failure process and tensile properties were contrasted and analyzed between intact and notch samples. Experiment and analysis results showed that positive Poisson＇s ratio effect gave rise to obvious waist binding and special inverted triangle loading area. All samples were sensitive to three kinds of notches. And notch sensitivity was closely related to notch form and notch length. The notch procession obviously deteriorated the mechanical properties of flexible warp knitting metal mesh. Sample with different notch lengths and breakage locations determined different tensile strengths that sample could bear. The fitting function of waist binding track satisfied the parabolic equation.

Preparation of Hydrophobic Fly Ash by Surface Modification and Oil-water Separation Devices

A simple and effective superhydrophobic mesh was designed and made to separate oil-water mixture. Alkali-activated fly ash reacted with 1-bromooctadecane to prepare superhydrophobic modified fly ash (MFA) with low surface energy through Williamson ether synthesis. The MFA powder was then coated uniformly on a stainless steel mesh (SSM) along with the epoxy resin E44 and curing agent T31 to give the superhydrophobic MFA-modified stainless steel mesh (MFA-SSM). The MFA-SSM has a high static water contact angle (CA) of 150.1°and can separate various oil or organic solvent from water with>95%separation efficiency. The oil-water separation efficiency remained high after 30 runs of petroleum ether/water separation.The developed superhydrophobic stainless steel mesh is expected to have wider use in oil-water separation.