Capillary Property of Entangled Porous Metallic Wire materials and Its Application in Fluid Buffers:Theoretical Analysis and Experimental Study

Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property entangled porous metallic wire materials(EPMWM),this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment(such as artillery,mortar,etc.).Combined with the capillary model,porosity,hydraulic diameter,maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM.The calculation model of the damping force of the composite buffer was established.The low-speed impact test of the composite buffer was conducted.The parameters of the buffer under low-speed impact were identified according to the model,and the nonlinear model of damping force was obtained.The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively,and provide a new method for the buffer design of weapon equipment(such as artillery,mortar,etc.).

Study on response of metal wire in thermoacoustic imaging

Thermoacoustic imaging(TAI)is an emerging high-resolution and high-contrast imaging technology.In recent years,metal wires have been used in TAI experiments to quantitatively evaluate the spatial resolution of different systems.However,there is still a lack of analysis of the response characteristics and principles of metal wires in TAI.Through theoretical and simulation analyses,this paper proposes that the response of metal(copper)wires during TAI is equivalent to the response of antennas.More critically,the response of the copper wire is equivalent to the response of a half-wave dipole antenna.When its length is close to half the wavelength of the incident electromagnetic wave,it obtains the best response.In simulation,when the microwave excitation frequencies are 1.3 GHz,3.0 GHz,and 5.3 GHz,and the lengths of copper wires are separately set to 11 cm,5 cm,and 2.5 cm,the maximum SAR distribution and energy coupling effciency are obtained.This result is connected with the best response of half-wave dipole antennas with lengths of 11 cm,4.77 cm,and 2.7 cm under the theoretical design,respectively.Regarding the further application,TAI can be used to conduct guided minimally invasive surgery on surgical instrument imaging.Thus,this paper indicated that results can also guide the design of metal surgical instruments utilized in different microwave frequencies.

Surface plasmon wave propagation along single metal wire

Recently, the single metal wire （SW） has become attractive for its potential applications in the terahertz and higher frequency range. However, as the most simple and typical surface plasmon polariton （SPP） transmission line, its study seems far from enough. Many important transmission behaviours have not been explained satisfactorily from the viewpoint of physics. In this paper, making use of the modified Drude model （MDM） based on the Sommerfeld theory, the transmission behaviours of SPPs along SW are systemically investigated theoretically. Some important physical phenomena such as the mode transformation, the lifetime of the radiative mode and the resonance frequency are revealed, and their mechanisms are explored. The results obtained in the paper will facilitate a general understanding of the features and the physical essence of the SPP transmission, not only for SW itself but also for other SPP transmission lines.

Mechanical behavior of entangled metallic wire materials-polyurethane interpenetrating composites

Composite materials exhibit the impressive mechanical properties of high damping and stiffness,which cannot be attained by employing conventional single materials.Along these lines,a novel material architecture is presented in this work in order to fabricate composites with enhanced mechanical characteristics.More specifically,entangled metallic wire materials were used as the active matrix,whereas polyurethane was employed as the reinforcement elements.As a result,an entangled metallic wire material-polyurethane composite with high damping and stiffness was prepared by enforcing the vacuum infiltration method.On top of that,the mechanical properties(loss factor,energy consumption,and average stiffness)of the proposed composite materials were characterized by performing dynamic tests,and its fatigue characteristics were verified by the micro-interface bonding,as well as the macro-damage factor.The impact of the density,preloading spacing,loading amplitude,and exciting frequency on the mechanical properties of the composites were also thoroughly analyzed.The extracted results indicate that the mechanical properties of the composites were significantly enhanced than those of the pure materials due to the introduction of interface friction.Moreover,the average stiffness of the composites was about 10 times the respective value of the entangled metallic wire material.Interestingly,a rise in the loading period leads to some failure between the composite interfaces,which reduces the stiffness property but enhances the damping dissipation properties.Finally,a comprehensive dynamic mechanical model of the composites was established,while it was experimentally verified.The proposed composites possess higher damping features,i.e.,stiffness characteristics,and maintain better fatigue characteristics,which can broaden the application range of the composites.In addition,we provide a theoretical and experimental framework for the research and applications in the field of metal matrix composites.

Quasi-static and low-velocity impact mechanical behaviors of entangled porous metallic wire material under different temperatures

To improve the defense capability of military equipment under extreme conditions,impact-resistant and high-energy-consuming materials have to be developed.The damping characteristic of entangled porous metallic wire materials(EPMWM)for vibration isolation was previously investigated.In this paper,a study focusing on the impact-resistance of EPMWM with the consideration of ambient temperature is presented.The quasi-static and low-velocity impact mechanical behavior of EPMWM under different temperatures(25℃-300℃)are systematically studied.The results of the static compression test show that the damping energy dissipation of EPMWM increases with temperature while the nonlinear damping characteristics are gradually enhanced.During the impact experiments,the impact energy loss rate of EPMWM was between 65%and 85%,while the temperatures increased from 25℃to 300℃.Moreover,under the same drop impact conditions,the overall deformation of EPMWM decreases in the temperature range of 100℃-200℃.On the other hand,the impact stiffness,energy dissipation,and impact loss factor of EPMWM significantly increase with temperature.This can be attributed to an increase in temperature,which changes the thermal expansion coefficient and contact state of the internal wire helixes.Consequently,the energy dissipation mode(dry friction,air damping,and plastic deformation)of EPMWM is also altered.Therefore,the EPMWM may act as a potential candidate material for superior energy absorption applications.

Numerical and experimental evaluation for density-related thermal insulation capability of entangled porous metallic wire material

Entangled porous metallic wire material(EPMWM)has the potential as a thermal insulation material in defence and engineering.In order to optimize its thermophysical properties at the design stage,it is of great significance to reveal the thermal response mechanism of EPMWM based on its complex structural effects.In the present work,virtual manufacturing technology(VMT)was developed to restore the physics-based 3D model of EPMWM.On this basis,the transient thermal analysis is carried out to explore the contact-relevant thermal behavior of EPMWM,and then the spiral unit containing unique structural information are further extracted and counted.In particular,the thermal resistance network is numerically constructed based on the spiral unit through the thermoelectric analogy method to accurately predict the effective thermal conductivity(ETC)of EPMWM.Finally,the thermal diffusivity and specific heat of the samples were obtained by the laser thermal analyzer to calculate the ETC and thermal insulation factor of interest.The results show that the ETC of EPMWM increases with increasing temperature or reducing density under the experimental conditions.The numerical prediction is consistent with the experimental result and the average error is less than 4%.

The Effect of Nanometer Size Effect on the Optical Property of Metallic Wire Grid

We mainly investigated the effect of metallic wire grid on its optical property. At first, we give one simple model to deduce an expression which can describe the relationship of the optical property with the width of metallic wire grid. This expression could be used to calculate the reflectance of the metallic wire grid. We also give the corresponding computer simulation. Our simulation shows that the reflectance would increase when the width of metallic wire grid increase. The wider the metallic wire grid is, the higher the reflectance is. The reflectance would reach the maximum value only when the width is over the free path of electronic.

The Residual Strain Measurement of Thin Conductive Metal Wire after Electrical Failure with SEM Moir

In this study, the residual strain of a thin conductive metal wire on a polymer substrate after electrical failure is measured with SEM moir′e. Focused ion beam(FIB) milling is applied to fabricate micron moir′e gratings on the surfaces of constantan wires and the random phase shifting technique is used to process moir′e fringes. The virtual strain method is briefly introduced and used to calculate the real strain of specimens. In order to study the influence of a defect on the electrical failure of the constantan wire, experiments were conducted on two specimens, one with a crack, while the other one without any crack. By comparing the results, we found that the defect makes the critical beam current of electrical failure decrease. In addition, the specimens were subjected to compression after electrical failure, in agreement with the observed crack closure of the specimen. The successful results demonstrate that the moir′e method is effective to characterize the full-field deformation of constantan wires on the polymer membrane, and has a good potential for further application to the deformation measurement of thin films.

Electrical Discharge Machining of Al2024-65 vol%SiC Composites

In the present work, the wire electrical discharge machining（WEDM） process of the 65 vol% SiCp/2024 Al composite prepared by pressure infiltration methods has been investigated. The microstructure of the machined composite was characterized by scanning electron microscope, the average surface roughness（Ra）, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy（TEM） techniques. Three zones from the surface to the interior（melting zone, heat affected zone and un-affected zone） were found in the machined composites, while the face of SiC particles on the surface toward the outside was ‘‘cut＇＇ to be flat. Increase in Al and Si but decrease in C and O were observed in the core areas of the removed particles. Si phase, which was generated due to the decomposition of SiC, was detected after the WEDM process. The irregular and spherical particles were further observed by TEM. Based on the microstructure observation, it is suggested that the machining mechanism of 65 vol% SiCp/2024 Al composite was the combination of the melting of Al matrix and the decomposition of SiC particles.

具有拉伸塑性和明显增强的β弛豫行为的高能态非晶丝

本文通过Taylor-Uitovsky方法成功制备了高质量Fe基、Ni基、Co基非晶丝.与相同成分的传统非晶合金相比,该非晶丝表现出普遍的β弛豫增强和更高的能量状态,可以认为是高回春态的非晶丝.值得注意的是,这种非晶丝的能量增强率达到了216.38%,是目前各种增强非晶合金能量状态方法中的最高值.研究发现,β弛豫的增强归因于结构异质性引起的高能量状态,从而使得非晶丝具有优良的力学性能,跟相同成分的非晶条带相比,其断裂强度提高至3240 MPa,拉伸塑性应提高至1.7%.本研究从β弛豫的角度实现了高能态的非晶合金的制备,为打破强度和拉伸塑性之间的权衡提供了一个新见解.