Influence of iron powder content on the electromagnetic and mechanical performance of soft magnetic geopolymer composite

In the induction heating of airport pavement to remove snow and ice,soft magnetic geopolymer composite(SMGC)can be used to gather the dissipated electromagnetic energy,thus enhancing the energy utilization efficiency.The aim of this work is to analyze the influence mechanism of iron powder content on the electromagnetic and mechanical performance of SMGC,so as to provide theoretical guidance for the design of soft magnetic layer within airport pavement structure.The results show that the increase of iron powder content reduces the resistance and magnetoresistance of SMGC by decreasing the content of non-magnetic phases between iron powder.However,the reduction of iron powder spacing also provides a shorter transmission path for the inter-particle eddy currents in the SMGC specimen,which enhances the exchange coupling between iron powder,thus increasing the electromagnetic loss.Therefore,the compatibility between magnetic permeability and electromagnetic loss should be considered comprehensively in the mix design of SMGC.In addition,although iron powder can enhance the mechanical properties of SMGC by improving the density of geopolymer matrix,the excessive amount of iron powder can lead to a weak interfacial transition zone between geopolymer matrix and iron powder.According to the induction heating results,optimized SMGC can improve the energy transfer efficiency of induction heating by 24.03%.

Enhancement of the Mechanical Performance of SiCf/Phenolic Composites after High-temperature Pyrolysis Using ZrC/B_(4)C Particles

The composites were prepared by modifying silicon carbide fiber with particles of zirconium carbide(ZrC)and boron carbide(B_(4)C)and incorporating them into a phenolic resin matrix.The influence of ZrC and B_(4)C on the mechanical performance of SiCf/phenolic composites after high-temperature pyrolysis was studied through flexural performance test.The results show that the composite material has good thermal stability and high-temperature mechanical properties.After static ablation at 1400℃ for 15 minutes,the flexural strength of the composite material reaches 286 MPa,which is still 7.3%higher than at room temperature,indicating that the composite material still has good mechanical properties even after heat treatment at 1400℃.

Influence of Erosion Induced by NaCl on the Mechanical Performances of Alkali-Activated Mineral Admixtures

In this paper,the influence of NaCl freeze-thaw(F-T)cycles and dry-wet(D-W)alternations on theflexural,com-pressive and bonding strengths of alkali-activatedfly ash(FA)and a blast furnace slag powder(BFS)is investi-gated.The considered NaCl concentration is 3%.The effect of polypropylenefibers on the mechanical strengths is also examined.Scanning electron microscopy(SEM),thermogravimetry(TG)and X-ray diffraction(XRD)are selected to discern the mechanisms underpinning the NaCl-induced erosion.The obtained results indicate that the best results in terms of material resistance are obtained with admixtures containing 60%BFS and 40%FA in terms of mass ratio and 3%polypropylenefibers in terms of volume ratio.The maximum rates of decrease of theflexural,compressive and bonding strengths after 300 NaCl F-T cycles are 21.5%,20.3%and 22.6%,respec-tively.The corresponding rates of decrease due to NaCl D-W alternations are 28.1%,26.1%and 31.5%,respec-tively.The TG curves show that the alkali-activating activity of BFS is higher than that of FA.Moreover,in thefirst case,the microstructure of the hydration products is more compact.The results also show that NaCl F-T cycles lead to increasing cracks in the alkali-activated BFS.

Analysis of mechanical performance of braided esophageal stent structure and its wires

This paper aims to find the relationship between the structural parameters and the radial stiffness of the braided stent and to understand the stress distribution law of the wires. According to the equation of the space spiral curve, a three-dimensional parametrical geometrical model is constructed. The finite element model is built by using the beam-beam contact elements and 3D beam elements. The constituent nitinol wires are assumed to be linear elastic material. The finite element analysis figures out that the radial stiffness of the stent and the stress distribution of the wires are influenced by all the structural parameters. The helix pitch of the wires is the most important factor. Under the condition of the same load and other structural parameters remaining unchanged, when the number of wires is 24, the stress of the wire crosssection is at the minimum. A comparison between the vitro experimental results and the analytical results is conducted, and the data is consistent, which proves that the current finite element model can be used to appropriately predict the mechanical performance of the braided esophageal stents.

Effect of alloy composition and heat treatment on mechanical performance of 6xxx aluminum alloys

The effect of alloy composition and heat treatment, including natural ageing and pre-ageing, on the mechanical performance of eight 6xxx alloys designed with systematically varying Si, Mg and Cu contents was studied. The results show that not only the alloy composition and heat treatment before forming influence the formability, but also they have an effect on the paint bake response of the alloys. Increasing the alloy Si content, decreasing Mg/Si ratio and adding 0.3% Cu （mass fraction） were generally found to improve the tensile ductility and formability of the alloys studied, while pre-ageing was found to decrease these properties. A full property profile of these alloys in terms of strength, tensile ductility, work hardening, strain rate sensitivity, forming limit and paint bake response was presented.

Effect of Cerium on Mechanical Performance and Electrical Conductivity of Aluminum Rod for Electrical Purpose

The effect of rare earth element Ce on mechanical performance and electrical conductivity of aluminum rod for electrical purpose were studied under industrial production condition. Using optical microscope, SEM, TEM, EDS and X-ray diffractometer, the microstructure and phase composition of aluminum rod were measured and analyzed. The results indicate that the content of rare earth element Ce is between 0.05% -0.16% in the aluminum rod for electrical purpose. Its tensile strength is enhanced to some extent. The research also discovers that the tensile strength is enhanced remarkably with impurity element Si content increases. Because influence of Si is big to the conductivity, the Si content should be controlled continuously strictly in the aluminum for electrical purpose. Adding rare earth element Ce reduces the solid solubility of Si in the aluminum matrix, and the negative effect of Si on the aluminum conductor reduces effectively. So the limit of in Si content in aluminum rod for electrical purpose can be relaxed moderately.

Influence of bismuth on microstructure,thermal properties,mechanical performance,and interfacial behavior of SAC305−xBiCu solder joints

This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−xBiCu solder joints were investigated.Bi-doping modified the microstructure of the solder joints by refining the primaryβ-Sn and eutectic phases.Bi-doping below 2 wt.%dissolved in theβ-Sn matrix and formed a solid solution,whereas Bi additions equal to or greater than 2 wt.%formed Bi precipitates in theβ-Sn matrix.Solid solution strengthening and precipitation strengthening mechanisms in theβ-Sn matrix increased the ultimate tensile strength and microhardness of the alloy from 35.7 MPa and 12.6 HV to 55.3 MPa and 20.8 HV,respectively,but elongation decreased from 24.6%to 16.1%.The fracture surface of a solder joint containing 2 wt.%Bi was typical of a brittle failure rather than a ductile failure.The interfacial layer of all solder joints comprised two parallel IMC layers:a layer of Cu6Sn5 and a layer of Cu3Sn.The interfacial layer was thinner and the shear strength was greater in SAC305−xBiCu joints than in SAC305Cu solder joints.Therefore,small addition of Bi refined microstructure,reduced melting temperature and improved the mechanical performance of SAC305Cu solder joints.

Preparation and Mechanical Performance of Rare Earth- Containing Composite Elastomer

Rare earth -containing PSBR sheet was prepared by reaction of rare earth alkoxide with quaternary ammonium salt of pyridine modified SBR (PSBR) latex, and then it was blended with natural rubber (NR) to produce rare earth - containing composite elastomer. It is found that mechanical performance can be improved remarkably. Analyzed by infrared spectrometry (IR), differential scanning calorimetry (DSC) and cross-linking densitometry, the relationship between structure and performance was discussed.

Eliminating shrinkage defects and improving mechanical performance of large thin-walled ZL205A alloy castings by coupling travelling magnetic fields with sequential solidification

ZL205 A alloys with large thin-walled shape were continuously processed by coupling travelling magnetic fields(TMF)with sequential solidification,to eliminate the shrinkage defects and optimize the mechanical performance.Through experiments and simulations,the parameter optimization of TMF and the influence on feeding behavior,microstructure and properties were systematically studied.The results indicate that the magnetic force maximizes at the excitation current of 20 A and frequency of 200 Hz under the experimental conditions of this study,and increases from center to side-walls,which is more convenient to process thin-walled castings.TMF can break secondary dendritic arm and dendrites overlaps,widen feeding channels,prolong the feeding time,optimize the feeding paths,eliminate shrinkage defects and improve properties.Specifically,for as-cast state,TMF with excitation current of 20 A increases ultimate tensile strength,elongation and micro-hardness from 186 MPa,7.3%and 82.1 kg/mm^(2) to 221 MPa,11.7%and 100.5 kg/mm^(2),decreases porosity from 1.71%to 0.22%,and alters brittle fracture to ductile fracture.

Effects of Frost-damage on Mechanical Performance of Concrete

The aim of this study is to provide the quantificational change laws of strength,stiffness,and deformation capacity of frost-damaged concrete relating to a united index,the data were obtained by different researchers.Then the index of relative compressive strength（RCS） was introduced as the indicator of frost damage and a large number of mechanical performance testing data of frost-damaged concrete were collected and analyzed.By curve fitting,the correlations between RCS and the initial elastic modulus,the strain at peak compressive stress,and biaxial compressive strength,and tensile strength,and the strain at peak tensile stress were established.Thereafter,the analytical stress-strain response of frost-damaged concrete under monotonic loading was presented using RCS and compared with that of the experimental data.Moreover,an isotropic elastoplastic damage model of frost-damaged concrete subjected to repeated loading was established.Finally,we can systematically estimate the effects of frost-damage on the mechanical performance of concrete,which can be provided for the numerical simulation of frost-damaged concrete structures.

Full-scale multi-functional test platform for investigating mechanical performance of track–subgrade systems of high-speed railways

Motivated by the huge practical engineering demand for the fundamental understanding of mechanical characteristics of high-speed railway infrastructure,a fullscale multi-functional test platform for high-speed railway track–subgrade system is developed in this paper,and its main functions for investigating the mechanical performance of track–subgrade systems are elaborated with three typical experimental examples.Comprising the full-scale subgrade structure and all the five types of track structures adopted in Chinese high-speed railways,namely the CRTS I,the CRTS II and the CRTS III ballastless tracks,the double-block ballastless track and the ballasted track,the test platform is established strictly according to the construction standard of Chinese high-speed railways.Three kinds of effective loading methods are employed,including the real bogie loading,multi-point loading and the impact loading.Various types of sensors are adopted in different components of the five types of track–subgrade systems to measure the displacement,acceleration,pressure,structural strain and deformation,etc.Utilizing this test platform,both dynamic characteristics and long-term performance evolution of high-speed railway track–subgrade systems can be investigated,being able to satisfy the actual demand for large-scale operation of Chinese high-speed railways.As examples,three typical experimental studies are presented to elucidate the comprehensive functionalities of the full-scale multi-functional test platform for exploring the dynamic performance and its long-term evolution of ballastless track systems and for studying the long-term accumulative settlement of the ballasted track–subgrade system in high-speed railways.Some interesting phenomena and meaningful results are captured by the developed test platform,which provide a useful guidance for the scientific operation and maintenance of high-speed railway infrastructure.

Structure and Mechanical Performance of Nitrogen Doped Diamond-like Carbon Films

Nitrogen doped diamond-like carbon （DLC：N） films were prepared by electron cyclotron resonance chemical vapor deposition （ECR-CVD） on polycrystalline Si chips. Film thickness is about 50 nm. Auger electron spectroscopy （AES） was used to evaluate nitrogen content, and increasing N2 flow improved N content from 0 to 7.6%. Raman and X-ray photoelectron spectroscopy （XPS） analysis results reveal CN-sp^3C and N-sp^2C structure. With increasing the N2 flow, sp^3C decreases from 73.74% down to 42.66%, and so does N-sp^3C from 68.04% down to 20.23%. The hardness decreases from 29.18 GPa down to 19.74 GPa, and the Young＇s modulus from 193.03 GPa down to 144.52 GPa.

Nonlinear Finite Element Analysis of Mechanical Performance of Reinforced Concrete Short-Limb Shear Wall

On the basis of test, nonlinear finite element analysis of reinforcedconcrete (R. C) short-limb shear walls under monotonic horizontal load are carried out by ANSYSprogram in order to understand the evolution of cracking, deformation and failure course of thespecimens. At the same time, the results of numerical calculation are compared with the results oftest. The results indicate that, under monotonic horizontal load the failures of the specimens withflange wall and without flange wall all occur at the intersections of lintel bottom and limb ofwall, the failures also occur at the bottom of limb; the load-displacement curve of wall withoutflange is steeper than that of wall with flange, and the ductility is worse than that of wall withflange; the results, such as cracking, deformation, yield load and so on of finite element analysisagree well with the results of test. These results provide theoretical basis of study andapplication of R. C short-limb shear wall.

Effect of High-temperature Annealing on Mechanical Performance and Microstructures of Different Oxygen SiC Fibers

In order to explore the effect of high-temperature annealing on the mechanical performances and microstructures of different oxygen SiC fibers, two types of silicon carbide（SiC）-based fibers, specified as XD-SiC fibers（low oxygen） and Nicalon-201 fibers（high oxygen）, were annealed in Ar for 1 h at 800 ℃, 1 000 and 1 200 ℃, respectively. Mechanical properties of these fibers were characterized via a monofilament tensile method, with observation of the damaged monofilament by SEM. Also, the effects of annealing on the microstructure and chemical compositions of the fibers were studied. The experimental results indicated that the tensile strength decreased with the increase of annealing temperatures,after annealing-treatment at 1200℃, XD-SiC fibers remained 84% of its original strength, while Nicalon-201 fibers remained only 58% of its original strength. Crystallization and chemical composition of the fibers are the dominating factors for their mechanical performance at high temperatures. The microstructure changes of XD-SiC fibers are mainly composed of the growth of β-SiC, for Nicalon-201 fibers, evaporation of gases is the main change for microstructure.

Research of dynamic mechanical performance of cement rock

As Daqing Oilfield is developing oil layer with a big potential, the requirement for the quality of well cementation is higher than ever before. Cement rock is a brittle material containing a great number of microcracks and defects. In order to reduce the damage to cement ring and improve sealed cementing property at the interface, it is necessary to conduct research on the modification of the cement rock available. According to the principle of super mixed composite materials, various fillers are added to the ingredients of cement rock.Dynamic fracture toughness of cement rock will be changed under the influence of filler. In order to study the damage mechanism of the cement circle during perforation and carry out comprehensive experiments on preventing and resisting connection, a kind of comprehensive experiment equipment used to simulate perforation and multi-functional equipment for testing the dynamic properties of the material are designed. Experimental study of the dynamical mechanical performance of original and some improved cement rock and experiment used to simulate the well cementation and perforation are carried out. Standard for dynamical mechanical performance of the cement rock with fine impact resistance and mechanical properties of some improved cement rock are also given.

Biomimetic design of highly flexible metal oxide nanofibrous membranes with exceptional mechanical performance for superior phosphopeptide enrichment

Developing free-standing and mechanical robust membrane materials capable of superior enrichment of phosphopeptides for analyzing and identifying the specific phosphoproteome of cancer cells is significant in understanding the molecular mechanisms of cancer development and exploring new therapeutic approaches,but still a significant challenge in materials design.To this end,we firstly constructed highly flexible ZrTiO_(4) nanofibrous membranes(NFMs)with excellent mechanical stability through a cost-effective and scalable electrospinning and subsequent calcination technique.Then,to further increase the enrichment capacity of the phosphopeptide,the biomimetic TiO_(2)@ZrTiO_(4) NFMs with root hair or leaf like branch microstructure are developed by the hydrothermal post-synthetic modification of ZrTiO_(4) NFMs through growing unfurling TiO_(2) nanosheets onto the ZrTiO_(4) nanofibers.Importantly,remarkable flexibility and mechanical stability enable the resulting TiO_(2)@ZrTiO_(4) NFMs excellent practicability,while the biomimetic microstructure allows it outstanding enrichment ability of the phosphopeptide and identification ability of the specific phosphoproteins in the digest of cervical cancer cells.Specifically,6770 phosphopeptides can be enriched by TiO_(2)@ZrTiO_(4) NFMs(2205 corresponding phosphoproteins can be identified),and the value is much higher than that of ZrTiO_(4) NFMs(6399 phosphopeptides and 2132 identified phosphoproteins)and commercial high-performance TiO_(2) particles(4525 phosphopeptides and 1811 identified phosphoproteins).These results demonstrate the super ability of TiO_(2)@ZrTiO_(4) NFMs in phosphopeptide enrichment and great potential for exploring the pathogenesis of cancer.

Effect of synthetic fibers on the mechanical performance of asphalt mixture:A review

Numerous studies showed that synthetic fibers are effective for reinforcing the mechanical performance of the asphalt mixture due to their high strength properties,ductility,and durability characteristics.In this paper,the objective is to present a review of the reinforcement effect of synthetic fiber on the mechanical performance of the asphalt mixture.This paper reviews the relevant literature on the characterizations and applications of synthetic fibers to improve different mechanical properties of asphalt mixes,which can provide a reference for the applications and development of synthetic fibers in asphalt pavement.The characteristics of common synthetic fibers are introduced and the utilization of synthetic fibers in asphalt mixture is discussed.Different surface treatment methods for fiber are reviewed and it is found that surface treatment can improve the performance of the synthetic fibers in asphalt mixtures,especially the chemical surface treatment method.The influence of synthetic fiber addition on the mechanical properties of the asphalt concrete such as rutting resistance,tensile strength,water stability performance,and cracking resistance are then discussed.The research results show that aramid,glass,and polyester fibers improve the fatigue cracking resistance of asphalt mixture.Polyester fibers,polyamide fibers,and carbon fibers are used to improve resistance to the permanent deformation of asphalt pavement.

Influence of heat treatment on microstructure,mechanical and corrosion behavior of WE43 alloy fabricated by laser-beam powder bed fusion

Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility.

Classification of inelastic deformation and material-intrinsic indices about mechanical performance of general solid matter

The present article is aimed to detect material-intrinsic indices that can be used to supervise the mechanical performance of general solid matter.The novelty carried in this article can be summarised as follows.Firstly,an inelastic deformation state of almost any solid matter can be treated as the combination of two fundamental modes due to different microscopic causation:Mode I inelastic distortion due to the movement of sliding types of defects and Mode II inelastic dilation due to the evolution of voids/bubbles.Secondly,each inelastic deformation mode is characterised by a single principal inelastic deformation descriptor(PIDD):Mode I by a newly introduced quantity of maximum distortional angle changeαand Mode II by the logarithm of dilating magnificationω.In particular,the concept of maximum distortional angle change gives rise to a geometrically intuitive yield criterion ofα>α_(c),which in situations of small deformation,is shown to asymptote von Mise's,and to become Tresca's in cases of plane stress.Thirdly,the deformation process of a solid matter under monotonic and ambient loads is formulated by means of trajectories of thermodynamic equilibria with respect to the PIDD pair.Then a pair of physical quantities which measure the stresses needed to change the local PIDD state are singled out.Being termed as inelastic deformation resistances(IDRs),these two quantities are shown to depend only on the onsite atomic configurations.It is also shown that key descriptive properties about the mechanical behaviours of materials,such as ductility,are encoded in IDRs as functions of PIDDs.Hence the IDR pair may serve as material performance indices that may be more intrinsic than conventional stress-strain relationships.

Surface Deposition of Ni(OH)_(2) and Lattice Distortion Induce the Electrochromic Performance Decay of NiO Films in Alkaline Electrolyte

NiO,an anodic electrochromic material,has applications in energy-saving windows,intelligent displays,and military camouflage.However,its electrochromic mechanism and reasons for its performance degradation in alkaline aqueous electrolytes are complex and poorly understood,making it challenging to improve NiO thin films.We studied the phases and electrochemical characteristics of NiO films in different states(initial,colored,bleached and after 8000 cycles)and identified three main reasons for performance degradation.First,Ni(OH)_(2)is generated during electrochromic cycling and deposited on the NiO film surface,gradually yielding a NiO@Ni(OH)_(2)core-shell structure,isolating the internal NiO film from the electrolyte,and preventing ion transfer.Second,the core-shell structure causes the mode of electrical conduction to change from first-to second-order conduction,reducing the efficiency of ion transfer to the surface Ni(OH)_(2)layer.Third,Ni(OH)_(2)and NiOOH,which have similar crystal structures but different b-axis lattice parameters,are formed during electrochromic cycling,and large volume changes in the unit cell reduce the structural stability of the thin film.Finally,we clarified the mechanism of electrochromic performance degradation of NiO films in alkaline aqueous electrolytes and provide a route to activation of NiO films,which will promote the development of electrochromic technology.