bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Characteristics Generated by Solidification Crack During High Strength Steel Welding
Authors: Li Z M , Chen Z L
Published: March 2020

A multiscale method was developed to elaborate weld solidification crack mechanical field. A sequential thermo-mechanical finite element method (FEM) of butt-joint was performed to provide both of geometry and loading condition of submoel. Then mechanical behaviours generated by impurity was achieved by submodelling with embedded solidification cracks in terms of elasto-plastic FEM. The solidification initial cracks were geometrical discontinuity in nature and modelled as mechanical property discontinuity. Results show that additive stress and back stress are built-up at impurity-weld matrix interface. The developed modelling method was validated by solidification crack tests, X-ray tests together with fractography. The underlying mechanisms in suppression solidification cracking by adjustment of alloy contents in flux cored wire aiming to diminish the impurity size and improve the ductility of weld metal were revealed by developed method. Results show that, given a 9 percent increase of the weld metal ductility, a 29.6 percent decrease of the additive stress is achieved; and the longitudinal oriented impurity readily propagates crossing section rather than along impurity longitudinal tip. The susceptibility to cracking is distance-dependent, heavily on fields near to impurity and little on far field.
Study on Preparation of Fluorinated Photosensitive Copolymer and Surface Wettability Light Regulation
Authors: Chen Xu , Xu Lin , Yang Xiaoyu , Zhang Lin , Liu Tongtong , Zong Chuanyong , Zhang Shuxiang
Published: March 2020

Low surface energy and micro/nano structure are two key factors affecting the construction of hydrophobic surfaces. In this paper, a series of tetrafluoropropyl methacrylate (TFPMA) and 6- [4- [2- [4- (trifluoromethoxy) phenyl] diazenyl] phenoxy] hexyl acrylate (FAzo) random copolymer [P(TFPMA-co-FAzo)] of different monomer molar ratios were prepared by free radical solution polymerization; and the chemical structure of the copolymer was characterized in detail using FTIR and 1HNMR. The introduction of long-chain flexible acrylate components with high fluorine content can effectively reduce the surface energy of the material. When the molar ratio of TFPMA is increased to 70%, the static water contact angle on the surface of the copolymer film is increased to 90°. By doping 10 wt% micron-sized PTFE particles, the water contact angle on the surface of the copolymer film can be further increased to 105°; Meanwhile, based on the cis-trans isomerization reaction of the azobenzene component in the copolymer, light irradiation with different wavelengths can realize the rapid and reversible regulation of hydrophobic/hydrophilic properties on the surface of copolymer film. This method of combining low surface energy fluorine-containing component with photosensitive azobenzene to construct light-responsive hydrophobic surface has a good research prospect.
Formulation Design of Deep Watertight Connector
Authors: Yu Kaiben , Wang Honghao , Zong Le , Meng Qingjian , Yu Shengqi , Zhang Xiaobo
Published: March 2020

In order to make the watertight connector localized, this paper mainly studies the outer insulating material neoprene 2442 (CR2442) of the watertight connector from the material, and improves the physical and mechanical properties of the CR2442 and the adhesion of the CR2442 to the brass by designing the formula. The performance and finalization of the watertight connector molding and vulcanization molds are designed to meet the molding needs of watertight connectors. Through research, it is found that the CR2442 optimized by this paper has good physical and mechanical properties and adhesive properties.
Wear Prediction Model Based on the Fractal Contact Characteristics
Authors: Yun Rui-De , Ding Bei
Published: March 2020

A new fractal wear model is proposed. The new model is based on the multi-scale fractal contact model. Studying the elastoplastic and plastic state of contact asperities, the new wear model is established. The relationship between the amount of contact surface wear and the fractal dimension D, the characteristic coefficient G and the material property constant C is studied. Besides, wear coefficient of the rough contact surface is predicted. It can be seen from the results that the influence of the scale effect on contact surface must be considered, because of the asperities with the same deformation ?? will be in different contact state. The relationship between amount of wear in the new model and amount of wear in existing model has the same trend. When D = 1.45, the amount of wear is the lowest. With the increasing of G reflecting the roughness of contact surface, the wear amount is increasing. The material constant also has a certain influence on the wear amount, and the material with high hardness has low wear. The contributions of the amount of asperity wear (elastoplastic and plastic) have the same effect to the total wear amount. Besides, the result of new fractal wear coefficient and the result of classical have the same trend, however, the new wear model is more precise than the classical wear model and closer to the actual state.
Study on the Material Mechanical Properties of Aquaculture Net Cage
Authors: Liu Haiyang , Wang Shaomin , Yuan Taiping , Hu Yu , Huang Xiaohua
Published: March 2020

Due to the typhoon impacts, aquaculture net cages may be exposed to the risk of structural failure as a far-reaching aquaculture equipment. In addition, the fatigue problem of key components due to long-term marine alternating loads can not be ignored. The method is developed independently on processing samples of cage for testing its performance parameters, among which the fatigue Wohler curve is S = -1.022ln (N) + 22.201. By adapting the following methods: Mechanical test, Equivalent load finite element simulation and Full field finite element simulation respectively is verified each other, and the error is less than 5%. The key nodes of the stress concentration of the floating frame are mainly the welding point, the mooring point and the edge area of the I-beam frame at both sides. The damage of the cage which caused by tensile and bending loads should be considered at the same time. And the tensile strength 22.12 MPa and the bending strength 30.58 MPa could be taken as the evaluation standard for the elastic to plastic deformation. Structural fracture occurs when the elongation at break exceeds 340.18%. The fatigue of the cage is mainly because the stress is much greater than the fatigue limit 3.38 MPa. The material model test combined with structural mechanics simulation provides the basis for guiding the structural optimization design of the cage.
Ferrosilicate Hydroxide/Carbon Nanotube Material for Anode of Lithium Batteries
Authors: Jiang Xiaotong , Lu Pengyi , Hou Feng
Published: March 2020

A ferrosilicate hydroxide/carbon nanotube composite was prepared by a combination of floating chemical vapor deposition and hydrothermal method as a lithium-ion battery anode. The obtained film material has a capacity superior to that of the conventional graphite negative electrode, and has a reversible capacity of 569.5 mAh g−1 at 0.05 A g−1. The material has excellent rate performance and cycle stability. The material can still maintain a capacity of 178.5 mAh g−1 after 500 cycles under a high magnification of 3 A g-1, with a coulomb efficiency is 95-100%.
Equivalent Performance Analysis of Thermal-Mechanical of 3D Lattice Structure
Authors: Bai Yang , Wei Liang
Published: March 2020

In order to achieve the efficient and accurate thermal stress analysis of 3D lattice structure, basing on the principles of statics and thermodynamics, the elastic modulus and thermal conduction equivalent calculation formula of the lattice structure are deduced. The theoretical relationship between the relative elastic modulus, relative thermal conductivity and relative density of equivalent cells is obtained. Finally, the numerical simulation method is used to compare the simulation results and experimental results of the equivalent model and the meticulous model, and the efficiency and accuracy of the equivalent model mechanical analysis and heat conduction analysis are proved. On this premise, designers can quickly determine the size and thermodynamic properties of lattice cells when using a multi-layer pyramid structure. And this research lays the foundation for the rapid analysis of structural thermo-mechanical coupling.
Optimization of Preparation Method of Molecularly Imprinted Microspheres by Uniform Design
Authors: Zhou Qiang , Zhang Hong , Wang Yanhong
Published: March 2020

This work presented a simple and effective method for the preparation of molecularly imprinted microspheres (MIMPs) through multi-step swelling polymerization. To prepare carbofuran MIMP with a uniform size, the experiment of optimizing the dosage of reagents which used during synthesis based on uniform design (UD) method was performed. Six kinds of factors, namely methacrylic acid (MAA, functional monomer), ethylene glycol dimethacrylate (EGDMA, cross linker), polyvinyl alcohol (PVA, dispersant), dibutyl phthalate (DBP, sweller), polymerization temperature and polymerization speed were taken into account based on UD to perform the optimization experiment. The micromorphology of MIMP was characterized by scanning electron microscopy (SEM) and it showed that the particle sizes were between 6-8 μm. The results indicated that MIMP possessed good selectivity and specificity for carbofuran, which was an excellent material for adsorption and testing of carbofuran residues in food and environment.
Preparation of Chiral Stationary Phase by Dynamic Grafting BSA on the Organic-Silica Hybrid Monolithic Column Based on Schiff-Base Reaction
Authors: Sun Yue-Na , Li Pan , Chen Meng-Jiao , Lv Yun-Kai
Published: March 2020

The prepared hybrid monolithic column (HMC) with epoxy groups on the surface was reacted with polyethyleneimine, and then reacted with glutaraldehyde. The chiral monolithic column was prepared by dynamically grafting bovine serum albumin (BSA) onto the newly modified HMC by Schiff-base reaction. The obtained chiral monolithic column was characterized by SEM and IR. The effects of the concentration of the BSA solution, flow rate and grafting time on the grafting amount were optimized. The properties of chiral monolithic column were tested with benzoin as the chiral object. The results showed that the obtained grafting amount of BSA was 56.1 mg/g under the optimized conditions. The chiral monolithic column had homogeneous network skeleton structure and good reusability. The method of preparing chiral monolithic column had good reproducibility.
Research on the Restricted Growth of High-Quality Large Cubic Gem Diamond Crystals
Authors: Zhang Li , Chen Kui
Published: March 2020

In this paper, cubic gem diamond crystal was grown via the temperature gradient under high pressure and high temperature, with self-made alloy solvent and through adjusting the process of assembling and synthesis appropriately. Crystal characters of large hexahedral cubic diamond crystals grown during different times were researched, and the results show that, the radial growth rate of the synthetic crystal is larger than that of the axial growth rate under the experimental conditions. The radial growth rate of the synthesis of the crystal is 3.75 times than that of the axial growth rate within 20 hours. The synthesized high quality diamond crystal has cubic hexahedral morphology and high repeatability, which will be beneficial to the industrialization of high quality cubic hexahedral diamond crystal.
Reinforcement of Notched PBX Simulant Beams with CFRP Patches-Experimental Study
Authors: Wang Shengnan , Tang Mingfeng , Zhou Hongping
Published: March 2020

Strength degradation induced by geometrical discontinuities is a primary cause of structural failure for polymer bonded explosive (PBX). To restore structural integrity and extend service life, reinforcement of weakened PBX structures is urgently demanded. In the present work, carbon fiber reinforced polymer (CFRP) patches are employed to notched PBX simulant beams. By using digital image correlation (DIC) technique, the influences of CFRP patches on mechanical behavior of the beams under bending load are explored. Results show that the CFRP patches endows the beams with increased strength and stiffness. Due to the load-sharing and deformation-confining of the patches, stress concentration at the notch is relieved, and crack propagation in PBX simulant matrix is prevented. These discoveries may provide important enlightment for the reinforcement and repair of the weakened PBX structures, and in addition, provide basis to the potential application of CFRP patches in energetic materials.
Structure Solution of ACV-GLU Cocrystal by Combined XRD Refinement, 1D Solid State NMR and DFT Calculations
Authors: Li Ping , Liang Tingting , Liu Huan , Guo Jixin , Chu Jingjing , Qiu Lingfang , Duo Shuwang
Published: March 2020

The powder sample of ACV-GLU crystal complex was prepared by formic acid-assisted grinding. 13C and 15N chemical shifts were assigned by referring to the 1D NMR spectra of raw individual components. The crystal structure was first solved by Rietveld refinement. The calculated NMR parameters were compared with the experimental results to validate the proposed structure. ACV, an important antiviral drug, can be cocrystallized with GLU into a triclinic unit cell with a molar ratio of 1:1 where each unit cell consists of two ACV molecules and two GLU molecules. Six intermolecular hydrogen-bonding interactions exist in the cocrystal. An agreement between experimental and calculated NMR parameters would give a final confirmation of the correct model among the preliminary candidates. Such synergistic approach provides efficient and convincing method to obtain the crystal structure of powder cocrystal specimens.
Novel Dopant for Conductive Polymers: Spherical Polyelectrolyte Brushes
Authors: Su Na
Published: March 2020

Conductive polymers with special structure and excellent physical and chemical properties, have become a research focus in materials science since the first discovery in 1977. While a growing body of work in recent years has concentrated on the improvement of the electrical conductivity of conductive polymers by using doping technique. The spherical polyelectrolyte brushes (SPB) consisting of polyelectrolyte chains grafted densely to the surface of the core particles, have shown great promise of novel dopant for conductive polymers due to its spherical structure, high charge density and high grafting density. After summarizing the researches of the general dopant for conductive polymers, this review mainly emphasizes on the preparation, doping mechanism and advance prospect of conductive polymers doped with spherical polyelectrolyte brushes.
Synthesis, Structure and Magnetic Property of a Tricapped Trigonal Prismatic TbIII-Based 3d-4f Complex
Authors: Zhuang Jia-Jia , Chen Ming-Guang , Sun Yan-Bing , Hang Pei , Sui Yang , Tong Jia-Ping
Published: March 2020

A novel 3d-4f CoII/TbIII cluster [Co6Tb(Pic)6O3Cl3](H2O)6 (1) (Pic = 2-Picolinic acid) has been synthesized and characterized via X-ray crystallographic and magnetic measurements. X-ray crystallographic and continued shape measurements analysis revealed that the central Terbium (III) is coordinated in TbO9 geometry with D
3h
symmetry. Magnetic studies indicated the complex presents a magnetic anisotropy with ferrimagnetic interactions.
Thermal Shock Behavior of Polymer Bonded Explosive below and above the Viscous Flow Transition Temperature
Authors: Tang Mingfeng , Wang Shengnan , Li Ming
Published: March 2020

The effect of initial cooling temperatures on the thermal shock behavior of cylindrical polymer bonded explosive (PBX) was investigated by using a combined acoustic emission (AE) and strain gauge technique in fast air-cooling tests. Dissimilarity was observed below and above the viscous flow temperature (Tf) where the PBX exhibited brittle-ductile transition and temperature dependence on material properties. We found that cooling below Tf would lead to fracture with strong AE signals and a linear strain-time response followed by a sharply decline, while above Tf would generate weaker AE events and a non-linear strain history with soften response. A segmented characterization was proposed for the calculation of thermal shock resistance and the corresponding critical fracture temperature difference. This estimation fits well with our experimental and simulation results.
Experimental Study on Mechanical Properties of Fiber Composite Material Adhesion to Metal
Authors: Li Qinghua , Jiao Yuxin , Zhang Yan , Tian Ranran , Zeng Yu
Published: March 2020

The fiber composites were impregnated at different times and bonded to metal materials; the mechanical properties of the bonded composites were measured. In this article, two kinds of materials, the carbon fiber fabric and the Kevlar fiber fabric, were compounded with epoxy resin E51 to form the fiber fabric composite material. The composite material was bonded to the surface of 45 steel by modified epoxy resin adhesive. The bond strength of composites were measured by the tensile method of determination of the bond strength between vulcanized rubber and metal, the shear strength of composites were measured by Four-plate shear method of determination of the bond strength of vulcanized rubber and rigid metal sheets by the international standard ISO 1747-1976, to obtain the maximum bond strength and shear strength of the composite material, and the corresponding optimum immersion time of the carbon fiber fabric.
Electrodeposition Assisted Dynamic Assemblies of Chitosan/Alginate Composite Multi-Membrane
Authors: Xu Feiyang , Wang Dong , Yan Kun
Published: March 2020

Electrodeposition of natural polymer as an effective approach to improve bioactivity of the conductive substrate has receives much attentions in medical and other applications. In this work, we developed a novel chitosan/alginate (CS/ALG) multi-membrane on titanium plate via the electrodeposition assisted dynamic assembly approach. Specifically, the electrical signal induced CS coating can serve as a versatile platform for layer by layer assemblies of ALG into the multi-membrane through strong electrostatic interaction. The prepared multi-membranes exhibit great swelling performance and excellent mechanical properties at dried states, with the tensile stress and strain values reaching to 58.2 MPa and 4.25 % for the 10 layers sample. In summary, we believe such green, low cost and rapid fabrication approach and mild processing environment would spur great potential for construction of multi-functional coating and smart drug elution system on the conductive implants.
Glass Transition and Stress-Strain Curve of Polyaspartic Ester Polyurea at Different Tension Condition
Authors: Zhang Jian , Zhai Junxue , Lin Jinjian , Du Aihua , Qingguo Wang , Zhao Xijuan
Published: March 2020

The tensile properties of polyurethane are related to the microstructure due to the change of hydrogen bond and hard segment domains at different temperature and velocity. In this paper, the structure and glass transition before and after tensile breakage of polyaspartate (PAE) based polyurea (PU) coatings were analyzed by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and tensile strain energy of stress - strain curve. The PAE-PU has not changed its allophanoyl (C=O in urea) and amino (N-H) hydrogen bond content apparently by the comparison of their IR absorption peak height. The PAE-PU has two glass transition temperatures related to soft and hard segments, which move to greater distance after tension. Moreover, the Enthalpy relaxation accompanied by hard segment glass transition almost disappears after tensile break. The dependency of tensile curve of PAE-PU on tensile rate at the same temperature is different from ordinary polymer materials; i.e.it has greatest yielding, strength and strain energy at medial rate of 100mm/min rather than higher ones.
The Effects of the Recycled Polyethylene on the Properties of Special Material Blends for Pipe and Final Products
Authors: Sheng Li , Lu Xiaoying , Chi Liang , Xu Chunyan , Li Shuanhong
Published: March 2020

A detail comparison between recycled polyethylene (RPE) compounds and special material for pipe in respects of mechanical properties, antioxidant performance, metal contents and rheological behaviours was performed. The results showed that the MFR, the content of ash and typical metallic element of blends increased with the RPE component, while the OIT, fracture strain and impact strength tend to decrease. However, for those unused waste PE there’s no significant difference in most performance parameters compared with the new ones, especially when the RPE content was lower. In contrast, the content of typical metallic element such as Ferrum (Fe) and Calcium (Ca) can still be a crucial indicator for distinguishing the existence of RPE. Undoubtedly, the test of pipe products proved that the introduction of RPE caused the decrease of pressure resistance and resistance to slow cracking.
Infrared and Raman Spectral Analysis of the Polycrystalline Copper Hydroxonitrates
Authors: Fu Jianlong , Liu Xiaodong , Liu Lu , Meng Huamao , Wang Xinbo
Published: March 2020

Two kinds of vibration spectra (Mid-infrared and Raman) of the magnetic geometrical frustration compound copper hydroxonitrate (hydroxyl nitrate, or hydroxide nitrate, Cu2(OH)3NO3) polycrystalline powders, which were synthesized successfully by the hydrothermal and solid-state reaction methods, respectively, have been measured at room temperature and analyzed by referring to the assigning of the Gerhardtite (natural Cu2(OH)3NO3) and α/β/γ-Cu2(OH)3Cl. The result can give some help to analyze the quality of obtained related samples for the further low temperature spectral experiments, which can reveal the underlying physics of their exotic geometric frustration phenomena from the spectral viewpoint.
Influence of Solution Treatment on Microstructure and Electrical Conductivity of Wrought Al-15Si Alloy
Authors: Liu Fang , Jian Yongchao , Yu Fuxiao , Zhao Dazhi
Published: March 2020

In the present work, the microstructures and electrical conductivity of Al-15Si alloy in casting, extruding and solution treatment conditions were investigated. The results indicate that the extruded Al-15Si alloy has higher electrical conductivity. It has been revealed that the morphology of Si, iron element and grain boundary impact on electrical conductivity of the Al-Si alloy. With the revolution of the microstructure, these factors which lead to the changing electrical conductivity of the alloy are discussed in detail.
Optimization of Cooling System for Hot Forming Based on Orthogonal Experiment
Authors: Huang He
Published: March 2020

Taking the U-shaped part of 22MnB5 ultra-high-strength steel as an example, a finite element model of hot stamping is established. The temperature field distribution characteristics of the sheet during the hot forming process are analyzed by DEFORMV11.0 software combined with the orthogonal experimental design method. The diameter of the pipe, the distance from the pipe to the mold surface, and the distance between the pipe and the pipe will affect the temperature field of hot stamping. Then, the cooling system parameters is designed and optimized.
Effects of Different Atomization Method on Powder Property, Microstructure and Low Cycle Fatigue Property of FGH97 Alloy
Authors: Tan J J , Guo J Z , Long A P , Li Q T , Xiao L
Published: March 2020

Two kinds of Ni-based superalloy powders (P-powder and A-powder) were prepared from masteralloy melted via the process of vacuum induction melting (VIM) by plasma rotating electrode process (PREP) and argon atomization (AA) method, which were used to fabricate two different alloys (P-alloy and A-alloy) using the same hot isostatic pressing process and heat treatment process. The study of microstructure and mechanical properties of FGH97 alloy were conducted to demonstrate the effect of different routes of powders preparation on the microstructure and low-cycle fatigue properties. Results show that the particle size distribution of P-powder is narrower than A-powder, and overall is larger, and the size of the inclusions in the A-powder is much smaller than P-powder. And it has been found that the grain size of A-alloy is finer and γ’ phase is more uniform, compared with P-alloy, there is no residual dendrite, grain boundary carbides are intermittent punctate distribution; the strength of A-alloy is slightly higher, and the plasticity is better than P-alloy; at the same time, the crack initiation is formed at the site of slag inclusions, but the size of inclusions of A-alloy significantly smaller; accordingly, the resistance of low-cycle fatigue crack initiation of A-alloy is superior than that of P-alloy due to the fine powder prepared by the process of argon atomization, showing a life time of much more than 150 000 cycles, far better than P-alloy (<70000 cycles); and the fatigue property of A-alloy is very stable.
Contact Performance and Thermal Stability Improvement of Amorphous InGaZnO Thin-Film Transistors by Using a Buffer/Cu/Buffer Source/Drain Electrode Structure
Authors: Li Gongtan , Zhu Feng
Published: March 2020

This paper discussed the contact characteristics and thermal stability of a-IGZO TFT with various kinds of buffer/Cu/buffer electrode structure. The work found that the a-IGZO TFTs with Cu electrode and Mo/Cu/Mo electrode show worse thermal stability than these with ITO/Cu/ITO electrode. The work speculates that the contact performance deterioration after post-anneal was due to Cu oxidation and an interface separation between Mo and Cu, respectively. The work used the G-function method to discuss the contact performance of a-IGZO TFTs with the different kinds of S/D electrodes. The a-IGZO TFT with an ITO/Cu/ITO electrode shows a smaller contact resistance than the other TFTs and had an ohmic contact between the a-IGZO and ITO. In terms of thermal stability and contact performance, ITO/Cu/ITO electrode is a better choice than Mo/Cu/Mo electrode.
Feasibility of Evaluating Acoustoelastic Coefficient of Concrete under Tensile Stress with One-Sided Ultrasonic Method
Authors: Yang Yu , Zhang Shuo , Bao Ting , Wang Yi
Published: March 2020

In this paper, an experimental study on the feasibility of evaluating acoustoelastic coefficient of concrete with one-sided ultrasonic pulse method under tensile stress is conducted. Tensile load cycles are imposed on prismatic concrete specimens and ultrasonic wave velocities are measured simultaneously. Acoustoelastic coefficients are obtained by linear fit of the test results and compared to correlate results in literature. The feasibility of evaluating acoustoelastic coefficient of concrete with one-sided ultrasonic method under tensile stress is discussed.
Prediction of the Slump of Fly Ash Blended Concrete Based on Various Numerical Models
Authors: Wang Xiao-Yong
Published: March 2020

Slump is a fundamental engineering property of fly ash blended concrete. This study proposes various numerical models, such as multiple linear regression (MLR), artificial neural network (ANN), and genetic algorithm assisted artificial neural network (GA-ANN) for estimating the slump. First, the concrete slump is regressed as a multiple linear equation of water-to-binder ratio, water content, sand ratio, fly ash replacement ratio, air-entraining agent content, and superplasticizer contents. The correlation coefficient of the MLR method is 0.63. Second, the ANN model is set up, which consists of an input layer, a hidden layer, and output layer. Based on the backpropagation (BP) training method, the optimized network is found. The correlation coefficient between analysis results and experimental results of ANN model is 0.78. Third, GA is used to assist in the optimization process of ANN. The initial value of the hidden layer of ANN is generated by using a genetic algorithm (GA). The correlation coefficient of GAANN integrated model is 0.85. GA-ANN integrated model can make more accurate prediction results than MLR model and ANN model.
Application of High Stiffness Modulus Asphalt Mixture in Longitudinal Slope of Jiqing Expressway
Authors: Yang Weigang , Wang Xiaoyan , Liu Jiarong , Ma Shijie
Published: March 2020

In this paper, according to the French LCPC asphalt mixture design method, the high modulus asphalt mixture is designed. It is found that the designed high-stiffness modulus mixture has high water stability, high temperature resistance to rutting and fatigue performance. The high-speed and long-slope section was successfully promoted and applied, which solved the problem of the structure and material durability of the long-slope section of the expressway under heavy load conditions and prolonged the service life of the road.
Research on Calculation Method of Non-Road Mobile Machinery PEMS
Authors: Yong Li , Jian Ling , Ming Gao-Zhong
Published: March 2020

In this paper, four typical non-road mobile machinery test objects were used to test the actual operation of the machine’s NOx emissions using a portable emission measuring system (PEMS). The NTE method of the United States and the European work-based window method test data were used for processing and analysis of emissions. The research results show that the NTE method cannot be applied to the actual operation emission analysis of four non-road mobile machinery, and the work-based window method can accurately evaluate the emission levels of four non-road mobile machinery.
Experimental Study on High Performance Cement in Aeolian Sand Concrete
Authors: Yang Zhengxun , Tang Binpeng , Huo Zhiqiang
Published: March 2020

In order to alleviate the current shortage of river sand resources in China, the experimentation of producing C30 concrete utilizing the aeolian sand as fine aggregate was carried out, in this experimentation, high-performance cement was used instead of ordinary cement, the basic mechanical properties of aeolian sand concrete was tested after maintenance. The results show that the flexural strength of concrete with aeolian sand content of 30% is nearly 4 MPa, the compressive strength fits the standard requirement. The high-performance cement exhibits its superior cementation ability, and the application of aeolian sand in concrete is preliminarily realized.
Experimental Study and Analysis on Compressive and Tensile Behavior of Basalt Fibre Reinforced Concrete
Authors: Zhou Hao , Jia Bin , Huang Hui , Mou Yanling
Published: March 2020

Blending a certain proportion of basalt fiber into concrete improves the toughness of concrete, which enhances the tenacity and prevents cracking, thus avoiding the brittle behaviors of concrete. In this paper, the compressive and tensile tests of the concrete with different basalt fiber contents were carried out. Then, the test phenomena, failure modes, and mechanical properties were compared and analyzed to derive the relationship between the basalt fiber contents and the mechanical properties. The results showed that the improvement effect of the basalt fiber on the compressive strength of concrete was lower than that of tensile strength. When the basalt fiber content is 0.3% and 0.4%, the improvement effect was the highest. In the meanwhile, the correlation coefficient of the fiber physical and mechanical parameters and content was introduced to establish the calculation formula for the crack width of basalt fiber reinforced concrete. Finally, the toughness and crack resistance performance of basalt fiber concrete were evaluated by the fracture energy and characteristic length proposed by Hillerborg. The results showed that basalt fiber can significantly improve the toughness and crack resistance performance of concrete.
A Review on the Geopolymer Materials Used in Grouting Piles
Authors: Peng Shengjiang , Yang Dezhou , Wang Shijun , Ping Chang
Published: March 2020

Bored cast-in-place piles are often used in power transmission projects. However, common bored cast-in-place piles with mud wall protection had some shortcomings, such as complicated construction procedure, poor quality of concrete, low bearing capacity, and pollution caused by mud wall protection. In this paper, the construction technology, quality evaluation method and design calculation of the new technology of Continuous Flight Auger pile were summarized. In addition, this technology combining geopolymer high strength concrete material was proposed, and the application of this technology in power transmission projects was prospected.
Experimental and Numerical Investigation on Global Buckling of Q690 High Strength Steel Tubes under Axial Compression
Authors: Sun Shuchang , You Qiang , Gu Xin , Peng Yiliang
Published: March 2020

Due to the excellent bearing capacity, high-strength steel (yield stress ≥ 460 MPa) is gradually utilized in the design of super high-rise buildings, long-span bridges and other important structures to reduce section size and self-weight. In the present study, the axial compression test and numerical simulation were carried out to investigate the global buckling of high strength steel tubes. Eighteen specimens of Q690 high strength circular steel welded tubes were tested under axial compression to obtain the ultimate bearing capacity and buckling mode. An effective finite element numerical model incorporating the residual stress and geometric imperfection was established to analyse the influence of slenderness ratio, diameter thickness ratio and residual stress on the global stability coefficient. According to the calculation results, the column curve of Q690 circular steel tube was obtained and compared with three different codes. Finally, a formula to calculate the global stability coefficient of Q690 welded circular steel tubes was suggested.
Effect of Line Energy Density and Wall Thickness on the Top Surface Quality of AlSi10Mg Sample Fabricated via Selective Laser Melting
Authors: Dai Shimin , Zhu Haihong , Zeng Xiaoyan
Published: March 2020

The effect of line energy density (LED) and wall thickness on the top surface quality of AlSi10Mg sample fabricated by selective laser melting (SLM) has been investigated in this paper. It is observed that the surface morphology has great evolution which the molten track turns to regular and then to irregular with the increase in LED. The line roughness (Ra) and peak height (Rz) decrease first and then increase as the LED increases. The optimal LED for low Ra/Rz increases from 0.1389 J/mm to 0.30 J/mm with the wall thickness increases from 0.1 mm to 2 mm. This work can provide a guide of manufacturing complexy geometrical thin-walled parts with a fine top surface quality.
Numerical Analysis of Piezoelectric Signal of PVDF Membrane Flapping Wing in Flight
Authors: Cheng Yun , Li Daochun
Published: March 2020

As an organic piezoelectric material, polyvinylidene fluoride (PVDF) can be utilized to fabricate thin film with high mechanical properties, and this film can be used to form flapping wing membrane. This type of wing with piezoelectric effect can solve the problems of the flight conditions measurement of flapping-wing micro aerial vehicles (FMAVs) in practical flapping flight. This study focuses on analysing the voltage outputs generated by PVDF membrane, and proposes two output voltage signal characteristics that can be used to deduce the flight conditions of FMAV, i.e. the voltage wave scale and voltage wave phase difference. The linear plate theory and unsteady aerodynamics coupling with piezoelectric equation are adopted to calculated the voltages generated by inertia and aerodynamic forces. The reasons and applications of scale and phase difference are analysed and discussed, and practical examples are demonstrated to illustrate specific impacts on these two signals.
Review of IGBT Junction Temperature Extraction and Estimation Methods
Authors: Qiu X Z , Zhang G R , Chen W J , Yu T , Hou X M , Zhang Q Z , Xu G Q
Published: March 2020

IGBT is widely used in photovoltaic power generation, aerospace, electric vehicles, ships and other power electronic equipment due to its advantages such as simple driving, high power level, low power consumption, and good thermal stability. As the core component of power electronic equipment, IGBT has always been a major concern for manufacturers and users. Excessive temperature is considered to be the main cause of IGBT failure. In order to meet the needs of high reliability in these applications, it is important to manage and control the temperature of the IGBT. Therefore, how to estimate or measure the junction temperature of IGBT is the focus of research on IGBT reliability. This article introduces several published methods for measuring junction temperature, focuses on the Temperature sensitive electrical parameters (TSEP) method and thermal resistance network method, and conducts experimental verification through the IGBT double-pulse test platform. Trying to provide help for future junction temperature detection work.
Preparation of PZT Thin Film/Ni Particle Composite Magnetoelectric Materials
Authors: Di Yongjiang , Chen Sijing , Jiang Yang , Jia Bi , Cao Pengjun
Published: March 2020

Lead Zirconium Titanate (PZT) thin film magnetoelectric materials have widely application in controllable sensing and tuneable microwave devices. The PZT film ferroelectric domain was designingly distributed and reversed by using the piezoelectric power response technique. The magnetoelectric composite of PZT film and Ni particle was prepared by the ferroelectric spontaneous polarization separation photogenerated carrier, reduction Ni atom deposition on the PZT thin film ferroelectric positive domain region. The optical morphology, XRD and SEM morphology show that the Ni particles deposited on the PZT film increase first and then become more uniform with the extension of deposition time. The deposition time closely relate to the deposition effect of Ni particles, and the deposition effect is more obvious with time. After the photo-deposition, the surface particles of the unexcited domain film are scattered after the photo-deposition, and the shape of the deposited particles region in which the Ni particles are reduced is substantially similar to the write-domain pattern, and the particle diameter is about 10-20 nm.
Design of Stealth Bulletproof Material Based on Sub-Wavelength Absorbing Structure
Authors: Zhang Han , Zhang Zekui , Li Baoyi
Published: March 2020

When stealth bulletproof materials achieve performance through simple superposition of layers and layers, there is a problem that the weigh is heavier, and the coating or patch is easy to fall off, and the absorption rate is lower. In order to reduce the weight, broaden the frequency band, and increase the absorption rate, functional integrated design method base on absorbing sub-wavelength structure is adopted. According to the design principle of the absorbing sub-wavelength structure, a lightweight ballistic material is used as its dielectric substrate. Microstructure graphics are designed on the bulletproof medium. With the fusion of stealth and ballistic performance, the design of a new wide-band stealth ballistic material was completed. Test results show that the absorbing sub-wavelength structure based on the lightweight bulletproof material has an absorption rate of more than 90% in a wide frequency band of 4GH to 18GHz and 27GHz to 40 GHz. which does not affect the ballistic performance of the ballistic material itself, and reduces the stealth material layer in the stealth ballistic material. The effect of reducing thickness and weight loss is achieved. The feasibility of this method is verified, which is of great significance for improving the combat capability of new functional vehicles.
Harmless Preexisting Crack in Structures Made of Hydrogen-Embrittlement Sensitive Materials under Monotonic Tension
Authors: Liu He , Hamada Shigeru , Noguchi Hiroshi
Published: March 2020

The interaction of hydrogen with the dislocations in the plastic zone of preexisting cracks (pre-cracks) in engineering components generally degrades the ultimate tensile strength (UTS). Hence, the crack effect coupled with hydrogen-embrittlement (HE) is widely believed to be harmful in engineering applications. However, in this study, the UTS of shallow pre-cracked structures made of interstitial-free (IF) steel, which is a hydrogen-embrittlement sensitive material, may not be wakened in hydrogen environment. Results of cylinder specimens with saturated hydrogen were experimentally and microscope-analytically compared with that of specimens without hydrogen. Then, this anti-common-sense influence of hydrogen was attributed as follows: (1) the crack propagation assisted by hydrogen enhanced localized plasticity (HELP) is stable before the onset of plastic instability because of high fracture instability toughness; and (2) the plastic strain localization at tips of the pre-crack and secondary cracks resists the onset of plastic instability. Additionally, the applicability of such a shallow crack effect coupled with HE presented by this study in engineering applications was discussed.
Study on Microstructure and Mechanical Properties of TP321 Thick-Walled Stainless Steel Tube by CMT Welding
Authors: Lu Hailong
Published: March 2020

The CMT welding process of TP321 thick-walled stainless steel pipe was analyzed. The tensile properties, microstructures and phase composition of the welded joint were tested, and the effect of welding current on the microstructures and properties was studied. The results show that for the CMT welding of TP321 thick-walled stainless steel pipe, when the optimum welding current is 110A, the maximum tensile strength of welded joints reaches 643 MPa, 92.7% of base metal, and the elongation reaches 58.7%. The fracture location of welded joints is heat-affected zone, basically ductile fracture. With the increase of welding heat input, the precipitation of ferrite and carbide gradually increases in the weld structure of TP321 stainless steel. When the current is too high, the brittle σ phase of ferrite transformation will decrease, resulting in the decrease of strength and plasticity of welded joints.
Comparative Experimental Study on Mechanical Properties of Rubber Band and Metal Spring
Authors: Huang Yan , He Songlin
Published: March 2020

The tensile tests of a metal spring and a rubber band are studied comparatively. It is found that the elastic force of rubber band is proportional to its elongation in a certain range of deformation, which satisfies Hooke’s theorem. This is same as the result of the metal spring. By comparing the vibration property of the systems composed of metal spring and rubber band respectively, it is found that the property of “intrinsic” damped vibration of the rubber band oscillator is completely different from that of the viscous damped vibration of the harmonic oscillator. It is concluded that the static mechanical property of rubber band is similar to that of metal spring, but its dynamic mechanical property is completely different from that of metal spring.
The Dry Friction Damping Model and Vibration Characteristics of a Cylindrical Shell Structure with Damping-Ring
Authors: Nie Y Q , Jiang X H , Wang Y R , Wang N M
Published: March 2020

To effectively solve the design problem of the damping ring used in the rotating thin cylindrical shell structure of aeroengine, a dynamic analysis model of the combined structure is established, based on its natural modal analysis. The analytical expression of the friction force and the critical slipping angle is derived with reference to the basic theory of mechanics of materials, and also the predicting method of damping work and damping ratio is demonstrated based on the macro sliding model. For the given structure model, the dry friction damping characteristics of the damping ring are studied. The results show that there exist a critical speed and if exceeding it, the damping ring cannot work functionally. Under an identical nodal diameter and vibration stress, the damping ratio increases first and then decreases with the increasing speed with the increase of rotating speed. When the speed is constant, the lower the nodal diameter, the higher the damping ratio it provided. For a given nodal diameter and speed, as the allowable vibration stress increases, the damping ratio rises first and then decreases. In addition, the damping ratio has a linear relationship with the cross-section width of the damping ring.
Preparation and Characterization of β-Cyclodextrin Nanosponges and Study on Enhancing the Solubility of Insoluble Nicosulfuron
Authors: Liu Xiaofang , Li Wei , Xuan Guangshan
Published: March 2020

Nicosulfuron (NSF) is a water-insoluble and unstable sulfonylurea herbicide, which is mainly used in the treatment of stems and leaves after the corn seedling stage. Nanosponges (NS) have more interaction sites and higher drug encapsulation capabilities. In this paper, three kinds of β-cyclodextrin nanosponges (CDNS) were prepared by crosslinking β-cyclodextrin with diphenyl carbonate (DPC), pyromellitic dianhydride (PMDA) and epichlorohydrin (EP), respectively. The NSF-loaded CDNS were characterized by TEM, FTIR, DSC, TGA and XRD. The solubility, stability and biological activity of NSF were studied. The results showed NSFEP-CDNS could significantly enhance the solubility of NSF. In vitro release test, the cumulative release of NSF-EP-CDNS was 90.11%. Compared with pure NSF and NSF oil suspension, NSF-EP-CDNS had the strongest inhibitory effect on acetolactate synthase (ALS). In conclusion, CDNS have beneficial effects on the solubility, stability and biological activity of NSF.
Detection of Mercury Ions in Aqueous Solution by Fluorescence Spectrometry
Authors: Wang Chenguang , Zhao Yaxin , Lv Kuilin , Zhou Ziran , Lin Peng , Lv Yuguang
Published: March 2020

This paper proposes a simpler and operable method to replace the traditional detection method and detect the mercury ion in water samples quickly and easily. Firstly, the rhodamine derivatives are synthetised, then a rhodamine derivative fluorescent molecular probe is constructed and adopted to detect mercury ions in water samples. In order to detect mercury ions in aqueous solutions, the fluorescence spectroscopy was adopted in this experiment, and rhodamine derivatives were used as fluorescent molecular probes. The rhodamine and its corresponding derivatives were used to detect mercury ions in aqueous solutions. Different metal ions and different chlorides were added to the solution of the compound. Only the one with the addition of mercury ion shows a peak at 555 nm. Therefore, it is concluded that the mercury ion derivative has a better response to metal mercury ion.
Research on Lower Extremity Exoskeleton System Based on Elastic Energy Storage Components
Authors: Guo Kai , Zhao Shasha , Liu Bin , Liu Yongfeng , Zhang Yingying , Yang Hongbo
Published: March 2020

In this paper, we study the field of rehabilitation walker technology. The passive energy storage gravity support exoskeleton is suitable for patients with lower limb dysfunction or limited function caused by lower limb joint, muscle tissue damage or bone disease. The equipment studied in this paper can assist patients to carry out normal ground walking and up and down stairs, realize patient self-care, slow down the patient’s physiological pain, and reduce the economic and energy burden of the patient’s family members. As the proportion of the elderly population continues to rise, the physiological decline during the aging process makes the elderly’s limbs less flexible, with limb motor dysfunction and lower limb motor dysfunction. Manual laborers have long been engaged in labor with repetitive and long working hours. It is easy to cause occupational chronic musculoskeletal injuries or other occupational diseases by maintaining the same or improper working posture for a long time.