A reinforcing technique for the adhesive bonded composite joints using metallic wires

One of the strengthening methods of composite connection is the employment of reinforcing elements in the adhesive layer. Using of additional elements in the adhesive layer make uniform stress distribution and improves the strength and toughness of the connection. In this paper, metal wires were used to reinforce the adhesive joints of composites. The effects of the number of wires, wire diameter, wire stiffness, angle of wire and the adhesive type on the strength of the adhesive reinforced bonded composite joints were investigated experimentally and numerically. A finite element model was developed to study the stress distribution in the reinforced adhesive joints. The numerical results showed a good agreement with the experimental observation. It was found that increasing the number of wires and wire diameter, choosing a stiffer material for the wire and increasing the wire angle, uniform the stress distribution and reduced the maximum and average stress values in the adhesive layer. For the appropriate reinforcing wire parameters, the joint strength increased more than 90% in this study. It also observed that the using metal wires as a reinforcing element was more effective in the ductile adhesion than the brittle ones.     

Tensile loading behavior of carbon nanotube wires

The mechanical behavior of four carbon nanotube (CNT) wires, comprised of 1-yarn, 30-yarn, 60-yarn, and 100-yarn, was investigated under constant tension at two loading rates of 0.02 mm/s and 2 mm/s. Tests were conducted with both as-fabricated and pre-stressed wires. The ultimate tenacity or apparent ultimate tensile strength of all four wires was found to be independent of loading rate, with those for the single-yarn wire about twice those of the multiple-yarn wires. Strain at a given stress level and failure strain of the multiple-yarn wires before pre-stressing were almost an order of magnitude larger than those for the single-yarn wire, and this difference was reduced considerably after pre-stressing. The failure mechanisms of 1-yarn wire or twisted individual yarns in multiple-strand wires involved ductile (necking) deformation and fibrillar breakage. Inner yarns in multiple-yarn wires initially failed at the same location, followed by outer yarns failing at different locations. Additionally, sliding occurred between individual yarns, and twisting of the yarns accompanied by surface wear took place in the multiple-yarn wires, which contributed to their failure at a lower load compared to the single-yarn wire.     

Failure analysis of carbon nanotube wires

A failure analysis of four carbon nanotube (CNT) wires comprised of 1-, 30-, 60-, and 100-yarns was conducted when subjected to constant tension and cyclic tension–tension loading conditions. Each wire had different controlling mechanisms of failure. Tensile and cyclic load-induced failures were related to the movement within yarns and/or among yarns in the CNT wires. The 1-yarn CNT wire exhibited a ductile fracture when constant tensile load was applied; recoverable deformation bands were observed on bending and straightening. The 30-yarn CNT wire showed a variant/independent fibrillar failure under constant tensile loading condition, while it failed by biaxial rotation, bend and twist under cyclic loading condition. The 60-yarn CNT wire resulted in a stake and socket fibre fracture when loaded to failure in constant tension; however, in the cyclic loading condition, the wire failed by kink band process. The 100-yarn wire failure mechanism was controlled by the surface wear in both constant tension and fatigue loading conditions. This failure analysis study presents detailed fracture surface features that can be used to diagnose the cause of failure, develop failure mechanisms, and improve the properties of CNT wires when used in real-life applications.     

Wire bond behavior during molding operations of electronic packages

This paper presents some modeling work on the behavior of wire bonds during a typical transfer molding operation. In order to fill up the small recesses in a production size mold, transfer pressures as high as 1.000 psi are commonly required. The large driving pressure is potentially harmful to the fragile wire bonds. Lit the worst case scenario, the highly viscous melt front may cause enough shearing action to lift off the wire bonds completely. More often, however, wire sweeping is reported as one of the major causes of shorts in devices where long interconnect wires are looped between bond pads. Several interdependent factors govern the extent of wire sweep in a mold cavity of arbitrary geometry. The dimensions of the cavity, for instance, dictate the velocity of the melt front profile with the corresponding flow stresses and shear rates. The location of the chip to be encapsulated similarly influences the plastic filing pattern. So does the configuration of the particular chip design (e.g. planar vs recessed lead frames). Naturally, the severity of the problem is also controlled by the nature of the wires used during the bonding. For example, wire sweep may be controlled to a certain degree by tailoring the wire modulus to offer resiliency and spring- back after the melt front has swept across, but prior to curing. Furthermore, a low drag coefficient would also be obtained if some measure of control on the shape of the wire (e.g. circular vs rectangular cross-section) or the pro- file exposed (e.g. angle of orientation of the wires with respect to the flow) is exerted.     

水平条件下管内加丝的脉冲热管性能测试及分析

传统脉冲热管在0°倾角条件下传热性能低或不能正常运行,应用范围受到严重制约。采用4个弯管数为3,充液比为50%,工质为去离子水的闭式脉冲热管进行不同倾角条件下的启动和传热性能对比实验。4个试件中一个为传统的脉冲热管,其余3个管内分别插入一根0.7 mm,一根0.5 mm和两根0.35 mm的镍铬丝,镍铬丝与脉冲热管长度相同。结果发现,加丝后的脉冲热管对倾角的敏感度降低,水平方向上更容易启动,启动后运行更加平稳,而且传热性能得到大幅度提高。同时分析了丝在紫铜管中的位置对传热方式和传热性能的影响。     

螺纹克氏针与普通克氏针内固定治疗锁骨骨折的临床疗效对比研究

目的比较螺纹克氏针与普通克氏针内固定治疗锁骨骨折的临床疗效。方法将60例锁骨骨折患者随机分为两组,每组30人,分别行螺纹克氏针与普通克氏针切开复位内固定术。结果两组切口均甲级愈合。螺纹克氏针组的优良率明显高于普通克氏针组,两者相比差异显著。在两组患者中,分别有1例和3例出现克氏针滑脱。结论螺纹克氏针应用于锁骨骨折的内固定效果确切,而且术后可早期进行功能活动,值得临床推广应用。     

A Parametric Study of a Portable Magnetic Separator for Separation of Nanospheres from Circulatory System

A portable magnetic separator was proposed for in-vivo biomedical applications. In this prototype design, a matrix of alternating, parallel magnetizable wires, and biocompatible tubing is immersed into an externally applied magnetic field. The wires are magnetized and high magnetic fields as well as field gradients are created to trap blood-borne flowing magnetic nanospheres in the tube. In this paper, a parametric investigation was carried out to evaluate the capture efficiency of flowing magnetic nanospheres by a separator unit consisting of single tubing and four wires. The parameters include: mean blood velocity (1 to 20 cm/s); magnetic field strength (0.1 to 2.0 T); sphere size (500 nm to 1000 nm in radii); sphere magnetic material (iron, two types of magnetite) and magnetite content in the spheres (0.05 to 0.8 by weight); wire material (nickel, stainless steel 430, and Wairauite); wire length (2.0 to 20 cm); wire size (0.125 to 1.0 mm in radii); tubing size at a fixed ratio of tubing to wire diameter of unity. The results show that capture efficiencies of the spheres of well over 90% were achievable under reasonable human physiological conditions, provided that the mean blood velocities were below about 5.0 cm/s. The results also show that the magnetic separator performance could be improved by maximizing the applied magnetic field strength up to about 1.0 T and by reducing the size of the unit with tubing and wires of equal radii. The results help further optimize a prototype magnetic separator suitable for rapid sequestration of magnetic nanospheres from the human blood stream while accommodating necessary clinical boundary conditions.     

Interface Phonons and Polaron Effect in Quantum Wires

The theory of large radius polaron in the quantum wire is developed. The interaction of charge particles with interface optical phonons as well as with optical phonons localized in the quantum wire is taken into account. The interface phonon contribution is shown to be dominant for narrow quantum wires. The wave functions and polaron binding energy are found. It is determined that polaron binding energy depends on the electron mass inside the wire and on the polarization properties of the barrier material.     

碳原子线磁学性质的研究

碳原子线的制备是从马铃薯淀粉为固态碳源以Fe（NO3）3为催化剂前驱体,高温裂解制得。它的磁滞回线呈＂S＂形,一般只有铁磁性物质的磁滞回线才表现出＂S＂,但一般铁磁性物质在常温下的饱和磁矩很大,大约为300 emu/g是碳原子线的300倍,我们把碳原子线的这种磁学性质称之为类铁磁性。通过碳原子线的顺磁共振谱图计算得到每个碳原子有4.78个自由电子,说明碳原子线中有大量的未成对电子。     

Anomalous length-independent frontier resonant transmission peaks in armchair graphene nanoribbon molecular wires

Molecular wires constitute the building blocks for nanoscale interconnects. However, the exponential decrease in conductance with wire length severely limits their applications. We predict, using first principles calculations, that armchair graphene nanoribbon (AGNR) wires, connected by transverse zigzag edges to wider AGNR electrodes, can exhibit anomalous resonant transmission peaks that are nearly independent of the wire length. We propose a new model to explain the unusual length independence of peak energies from the locally repeating property of the wavefunction in the middle-AGNR. We further uncover that this locally repeating pattern originates from states of a perfect AGNR with infinite length. The pattern can be well preserved when the AGNR is connected to wider AGNR leads because of the zigzag edges serving as electron sources and drains. The length independence of peak widths results from the zigzag edges absorbing most of the wavefunction renormalization as the length increases, so that the coupling strength to the electrodes does not change significantly. These anomalous properties arising from intrinsic wavefunction properties of the AGNRs are in sharp contrast to typical transmission properties of traditional molecular wire junctions, which suggests promising potential application as “molecular wire” interconnects in nano-electronics.     

Metallurgical characterisation of high resilience stainless steel orthodontic wires

Nominally 0.4 mm diameter high resilience stainless steel orthodontic spring wires, as used in appliances (or braces) for the correction of children's malaligned teeth, are notoriously inconsistent in their clinical behaviour. This is principally due to a lack of compositional control and to the severe work hardening of the wire drawing process. A selection of the spring wires in clinical use has been investigated here to characterise them by means of spectrochemical analysis, tensile testing, potentiostatic polarisation, and ferromagnetic measurements. The study of these interrelating factors is suggested as a method of characterisation for the wires to ensure greater clinical consistency. The effects of bending and low temperature heat treatment on the wires have also been investigated.     

电线电缆阻燃化研究现状

分析了电线电缆火灾的成因和危害;简要介绍了低烟低卤阻燃聚氯乙烯电线电缆料的发展现状和方向;重点介绍了低烟无卤阻燃聚烯烃电线电缆料的阻燃机理和研究现状;提出了阻燃剂的无卤化、抑烟和低毒是当前和今后电线电缆阻燃研究领域的前沿课题,但在阻燃电缆的应用上还需进一步深入研究。     

Fabrication and Properties of High-Temperature Superconducting Wire by the Green-Fiber Method

Continuous silver-clad Y-123 wire has been fabricated from cofired green fibers produced by melt-spinning polymers loaded with Y-123 powders. Metal claddings are provided by coating with silver-alloy powder slurries. The sintered polycrystalline Y-123 wires have 77 K self-field critical current density ( J _c) values up to 2900 A/cm², with typical ranges in long lengths of about 1000 A/cm², but are weak linked. High- J _c wire is made by continuous melt texturing of the presintered wires. Values of J _c above 10 000 A/cm² at 77 K have been achieved.     

Bond strength between C3S paste and iron,copper or zinc wire and microstructure of interface

Bond strength between C₃S paste and iron, copper or zinc wire and microstructure of the interfacial region were examined by pull-out test and scanning electron microscope respectively. The bond strength between C₃S paste and iron wire at 28-day curing is larger than that between C₃S paste and copper or zinc wire. In the case of iron and copper wires, CSH and Ca(OH)₂ are formed in the paste at the interface. On the other hand, Ca[Zn(OH)₃·H₂O]₂, CSH and Ca(OH)₂ are formed in between C₃S paste and zinc wire. The relation between the development of bond strength and curing time is characteristic according to the kind of metal wires.     

Raman Light Scattering in System of Oriented Wires in Porous Silicon

Raman-light scattering in porous silicon samples with oriented quantum wires was studied. It was shown, that the experimental data depends on the type of organization of wire system. The explanation of observed effect is discussed.     

用于可焊性漆包线漆的聚酯多元醇的合成及性能测定

发展了一种聚酯多元醇,可望应用于制备新型的直焊性耐热漆包线漆。采用间苯二甲酸、己二酸、乙醇胺或乙二醇、三乙醇胺或甘油,通过熔融共缩聚合成一系列聚酯多元醇,然后用甲醚化氨基树脂及溶剂混合、配制成溶液,再涂制成漆包线。研究结果表明系列聚酯多元醇的分子量、酸值均符合漆包线漆制备的技术要求;采用乙醇胺代替乙二醇、三乙醇胺代替甘油在聚酯多元醇的合成反应中具有较高的缩聚反应活性,由此制备的聚酯多元醇具有在350℃至400℃的范围内更快速分解和分解残渣较少的特点,采用此聚酯多元醇作为主要成分、涂制的漆包线在400℃至460℃范围内下可直焊,介质损耗曲线的拐点温度可达到162℃、意味着耐热等级较高。     

高效电除雾器的研制和应用

介绍用于冶炼烟气和硫铁矿制酸过程的高效塑料电除雾器的研制。利用压缩空气用规定粒度的石英砂对PVC管内壁进行喷砂预处理,再经滚磨达到所要求的表而粗糙度,使PVC管在运行过程中表面形成一层连续的水膜,大大提高了导电性能。设计了一套极线试验装置,并根据试验结果研制出6种改进型的阴极极线。采用刚性框架固定极线,以防止其在高气速下摆动。高效电除雾器设计气速高达1．2-2．2m/s,二次电压为50-60 kV,比电流高达0．8-1．0 mA/m。在新厂建设和老厂改造中均有良好的应用前景。     

Phtocrosslinking of polyethylene for production of thin wall insulated wire

A photocrosslinking precess for polyethylene and its industrial irradiation apparatus has recently been developed and used successfully in the manufactre of thin wall crosslinked polyethylene-insulated wires. Polyethylene (PE) resin with the desired amounts of additives, such as photoinitiator, multifunctional crosslinker, and antioxidant is mixe homogeneously. The amixture of PE is granulated, and then extruded on a conductor wire. The coated PE layer in the melt is subsequently irradiated in a specially designed UV irradiation apparatus for 5 to 10 s. The studies show that the photocrosslinked PE-insulation high voltage television wires produced by this new technique possess excellent electrical and mchanical properties and much lower operating cost compared with wires produced by the electron beam crosslinking technique.     

Experimental study of flame spread over PE-insulated single copper core wire under varying pressure and electric current

In this study, the flame spread over a thin wire with overload current (0-16 A) has been experimentally investigated at both normal pressure (Hefei: altitude 50 m, 100 kPa) and reduced pressure (Lijiang: altitude 2400 m, 76 kPa; Lhasa: altitude 3650 m, 64 kPa). Polyethylene-insulated single-core wires, comprising Cu as the inner core of diameter 0.30, 0.50, and 0.80 mm and insulation thickness 0.15 and 0.30 mm, are used as samples. The experimental results clearly indicate that the height of the flame increases with the electric current and ambient pressure, but the flame width changes only slightly. At identical conditions, the finer the wire, the faster the flame spreads. The flame spread rate increases with the electric current and ambient pressure. A simplified thermal balance analysis concerning the load current is developed to calculate the flame spread rate, and the calculated flame spread rates are shown to be fairly consistent with the experimental values at different electric currents for different wires at both ambient pressures. In addition, the coupled effect of electric current and ambient pressure on the flame spread is discussed. These results may be meaningful for promoting the research process of wire fire safety.     

Characteristics of classical Kirchhoff's superposition law in carbon atomic wires connected in parallel

The classical Kirchhoff's superposition law is hard to realize in the molecular scale devices because the coupling between the juxtaposed molecules can lead to constructive or destructive quantum interferences [Vazquez et al. nature nanotechnology 2012, 7, 663; Zhu et al. Phys. Rev. B 2014, 89, 085427]. In view of this, we try to eliminate the quantum interference between the juxtaposed molecules by increasing the distance between them. Simple junctions of carbon atomic wire(s) coupled to zigzag graphene nanoribbon electrodes are chosen as our model. Interestingly, fine Kirchhoff's superposition law phenomenon is found when the distance between the two carbon atomic wires reaches 15.5 Å. At the distance 15.5 Å, the conductance for the double carbon atomic wire (DCAW) configuration is 1.96 times of that for single carbon atomic wire (SCAW) configuration and the current across the DCAW configuration keeps nearly two times of that across the SCAW configuration at the applied biases. In addition, the conductance superposition effect becomes better when the distance between the two wires increases further and the spin filtering effect is enhanced in the DCAW configuration.