检索结果-南通市图书馆

Fracture Characterization of High-Density Polyethylene materials Using the Energetic Criterias

在线全文

学校读者我要写书评

暂无评论

Computers, materials & Continua 2016年第3期51卷 187-201页

作者： m.n.D.Cherief m.Elmeguenni m.Benguediab University Djilali Liabès of Sidi Bel AbèssAlgeria

Impact behavior of polymers has received considerable attention in recent years,and much work based on fracture mechanic approaches has been carried *** this paper,fracture behavior in large deformation of a high density polyethylene(HDPE)materials was investigated through experim.n.al impact testing on single edge notched specim.n.SEnB)and by using theoretical and analytical fracture criteria ***,a review of the main fracture criteria is given in order to characterize the toughness of this polymer in the both cases(static and dynamic).The fractured specim.n. obtained from the Charpy impact test were characterized with respect to their fracture *** zones of the fracture surface can be assigned to different stages and mechanisms of the fracture ***,for a better understanding of fracture and damage mechanisms and to provide the best estimation of fracture toughness in impact,an experim.n.al approach based on microscopic observations(SEm)was used.

关键词： Impact Fracture toughness High-density polyethylene Brittle fracture Ductile fracture

Simulation of wheel and rail profile wear:a review of numerical models

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Railway Engineering Science 2022年第4期30卷 403-436页

作者： n.Bosso m.magelli n.Zampieri Departm.n. of mechanical and Aerospace Engineering Politecnico Di TorinoC.so Duca degli Abruzzi 2410129 TurinItaly

The developm.n. of numerical models able to compute the wheel and rail profile wear is essential to improve the scheduling of maintenance operations required to restore the original profile *** work surveys the main numerical models in the literature for the evaluation of the uniform wear of wheel and rail *** standard structure of these tools includes a multibody simulation of the wheel-track coupled dynamics and a wear module implem.n.ing an experim.n.al wear ***,the models are classified according to the strategy adopted for the worn profile update,ranging from models perform.n. a single computation to models based on an online comm.n.cation between the dynamic and wear ***,the most comm.n.strategy nowadays relies on an iteration of dynamic simulations in which the profiles are left unchanged,with co-simulation techniques often adopted to increase the computational *** is still needed to improve the accuracy of the current *** experim.n.al campaigns should be carried out to obtain refined wear coefficients and models,while strategies for the evaluation of both longitudinal and transversal wear,also considering the effects of tread braking,should be implem.n.ed to obtain accurate damage models.

关键词： Wear Wheel and rail profiles Wheel-rail contact Railway vehicle dynamics multibody simulation Co-simulation

The effect of positive/negative ion on the dust grain charging process in a Vasyliunas-Cairns (VC)-distributed dusty plasma system

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2019年第6期21卷 58-62页

作者： n AHmAD A A ABID Y AL-HADEETHI m.n.S QURESHI Saqib REHmAn Departm.n. of Engineering and Applied Physics University of Science and Technology of China Hefei 230026 People's Republic of China CAS Key Laboratory of Geospace Environm.n. Department of Geophysics and Planetary ScienceUniversity of Science and Technology of China Hefei 230026 People's Republic of China Departm.n. of Physics Faculty of Sciences King Abdulaziz Unniversity Jeddah 21589 Saudi Arabia Departm.n. of Physics GC University Lahore 54000 Pakistan Departm.n. of Chemical Physics University of Science and Technology of China Hefei 230026People's Republic of China

Charging mechanism of dust particles has been considered as a growing research area in dusty plasma physics because of its exciting *** this paper,we consider a low-temperature non-equilibrium multispecies plasma model,which consists of Vasyliunas-Caims (VC) distributed electrons,negative/positive stream.n. ions,and negatively-charged dust grains to explain the charging mechanism of dust *** main theme of this work is to derive expressions of currents for negatively-charged dust grains (considering an equilibrium state position) in the plasma environm.n. comprised of electrons and positive/negative stream.n. ions using the VC distribution *** proposed model shows that the dust grain surface potential is significantly affected by different plasma parameters such as the negative ion stream.n. velocity (Sn),positive ion stream.n. velocity (Si),spectral indices of VC distribution,negative ion charging state (Zn),positive ion charging state (Zi),and negative ion number density (ρ).

关键词： dust grain surface potential vasyliunas-cairns power law velocity distribution function multi species plasma

Experim.n.al study on microstructural and corrosion behaviors of friction stir processed steel with CoCrFeCuTi HEA reinforcem.n. and effect of annealing

在线全文

学校读者我要写书评

暂无评论

Science China Technological Sciences 2025年第1期 233-250页

作者： S.Aravind KRISHnA n.RADHIKA Alokesh PRAm.n.K n.JEYAPRAKASH Departm.n. of mechanical Engineering Amrita School of EngineeringAmrita Vishwa Vidyapeetham School of Civil and mechanical Engineering Curtin University School of mechanical and Electrical Engineering China University of Mining and Technology

The ability to perform against extreme corrosion environm.n.s in stainless steel depreciates under challenging conditions in industrial applications. This can be resolved by employing surface modification techniques to modify the surface with the required characteristics. The present study investigates the outcomes of friction stir processing of SS304 with CoCrFeCuTi high entropy alloy(HEA) as reinforcem.n. and the property enhancem.n.s post-annealing. The synthesized CoCrFeCuTi HEA exhibited irregular fragm.n.s with 17 μm mean particle size and body centred cubic(BCC) phase. The microstructure of the processed surface revealed ultra-refined grains with a uniform distribution of HEA filler. The microstructures of the samples annealed at 400℃, 550℃, 700℃ and 850℃ for 2 h also showed significant grain growth and grain refinem.n.s. The processed sample with HEA reinforcem.n. annealed at 700℃ exhibited enhanced microhardness and tensile strength by 63% and 0.88 times than that of the processed sample with HEA pre-annealing. The subsequent electrochemical corrosion test displayed better corrosion resistance for the HEA-processed and annealed sample. Hot corrosion tests at 900℃ showcased excellent resistance for the HEA processed and annealed samples by 14.92%, 12.75%, and 14.83% against the samples pre-annealed under three different salt mixtures, and the corroded surface was analyzed.

关键词：

Chirping instabilities produced by a runaway electron beam at a spherical tokamak

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Plasma Science and Technology 2023年第7期25卷 19-24页

作者： I m BALACHEnKOV n n BAKHAREV V K GUSEV m V ILIASOVA E m KHILKEVICH P S KOREnEV A E KOnKOV V B m.n.EV Yu V mITRIZHKIn m I PATROV Yu V PETROV n V SAKHAROV A E SHEVELEV O m SKREKEL Ioffe Institute Saint-Petersburg 194021Russia Lom.n.sov moscow State University Moscow 119991Russia

Two different types of mHD instabilities with rapidly chirping frequency were found to arise in the Globus-m2 spherical tokamak in substantially different frequency *** first type arises at frequencies of an order of 1 mHz in ohmic plasmas at relatively low density(n_(e))m^(-3) in a wide range of toroidal magnetic fields and plasma *** type of instability was identified as compressional Alfven waves,driven by electrons,accelerated during a sawtooth *** was found that the mode frequency is sweeping in time,according to the Berk-Breizm.n.hole-clump nonlinear chirping *** second type of wave arises in a specific single-swing regime of the central solenoid current with a very narrow plasma column,when the plasma tends to decay at extremely low density(n_(e))m^(-3) and,in fact,is an instability of the runaway electron *** exited modes cover the whole observed frequency range and are divided into several(two or three)frequency regions:approximately 0-30 mHz,60-120 mHz and sometimes 30-60 *** of the branches was also *** chirps are more rapid than for 1 mHz Alfven instability and follow an exponential *** paper,to our knowledge,is the first report of frequency chirping instabilities excited by accelerated electrons at a spherical tokamak.

关键词： Alfvén waves chirping instability spherical tokamak runaway electrons

Progressive failure analysis of notched composite plate by utilizing macro mechanics approach

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2021年第3期15卷 623-642页

作者： Seyed m.n.GHOREISHI mahdi FAKOOR Ahmad AZIZI Faculty of new Sciences and Technologies University of TehranTehran***Iran Departm.n. of mechanical Engineering Science and Research BranchIslamic Azad UniversityTehran***Iran

In this study,gradual and sudden reduction methods were combined to simulate a progressive failure in notched composite plates using a macro mechanics *** the presented method,a progressive failure is simulated based on a linear softening law prior to a catastrophic failure,and thereafter,sudden reduction methods are employed for modeling a progressive *** combination method significantly reduces the computational cost and is also capable of simultaneously predicting the first and last ply failures(LPFs)in composite *** proposed method is intended to predict the first ply failure(FPF),LPF,and dom.n.nt failure modes of carbon/epoxy and glass/epoxy notched composite *** addition,the effects of mechanical properties and different stacking sequences on the propagation of damage in notched composite plates were *** results of the presented method were compared with experim.n.al data previously reported in the *** comparing the numerical and experim.n.al data,it is revealed that the proposed method can accurately simulate the failure propagation in notched composite plates at a low computational cost.

关键词： progressive failure notched composite plate Hashin failure criterion macro mechanics approach finite elem.n. method

High-temperature deformation behaviour of duplex stainless steel with hard boronised layer

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2021年第2期28卷 244-253页

作者： n.m.Sultan I.Jauhari R.Saidan m.F.m.Sabri Departm.n. of mechanical Engineering Faculty of EngineeringUniversity MalayaKuala Lumpur 50603Malaysia

In order to understand the high-temperature deformation behaviour of alloy having hard surface layer,thermo-mechanically treated duplex stainless steel(DSS)is boronised for 0.75-6 h at 1223 K and subsequently deformed under compression mode at the same temperature under strain rate condition of 1×10^(-3),2×10^(-4) and 6×10^(-5) s^(-1) until strain of *** substrate microstructure is almost isotropic with grain size after boronising with layer thickness between 1.61 and 2.74μm.X-ray diffraction results confirm the formation of boride on DSS *** surface hardness of DSS increases from 387 to 1000-2400 HV after *** boronised layer with thickness of 20-40μm is formed at DSS *** results show that the flow stress of the deformation increases with the strain rate and boronising *** the boronised samples,the flow stress range is between 5 and 89 *** determ.n. the actual effect of the boronised layer on the flow stress,the results are also compared with those from un-boronised samples having similar *** results suggest that at a constant grain size,even with the hardest layer,the effect of hard surface layer on the flow stress almost could be negligible when the deformation rate is slow,but at faster deformation rate,even in the layer with the least hardness,the flow stress shows a significant *** is also observed that the hard boride surface disintegration could be avoided at a sufficiently low deformation flow stress that could be attributed to superplasticity.

关键词： High-temperature deformation Superplasticity Duplex stainless steel Hard boride layer Surface integrity Grain size effect Strain rate effect

Water Resource m.n.gem.n. in the Intermountain Izeh Plain,Southwest of Iran

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of mountain Science 2009年第1期6卷 25-41页

作者： Kalantari.n Pawar.n.J Keshavarzi.m.R Geology Departm.n. Shahid Chamran UniversityAhvazIran Geology Departm.n. University of PunePune-411 007India

Ever growing dem.n. for water for agricultural activities in the Izeh Plain has enhanced the use of groundwater. Due to enormous groundwater abstraction since 1985, the overall static water level has receded by more than 5 meters reflecting that the aquifer is under stress condition. As a result, interest is focused on application of artificial recharge as an option for groundwater m.n.gem.n. to augm.n. water supply in this area. Therefore, in the present investigations, suitable sites for artificial recharge were selected by an integrated surface and sub-surface assessm.n. of the area. On the basis of the data collected from four target points, it was realized that the selected sites for artificial recharge could not meet water dem.n. of the area. In this study attention was also paid to utilization of the existing miangran Lake water as an alternative to combat water shortage for irrigation. The study further indicated that the available miangran Lake water could be used for irrigation of the reclaimed agricultural land and enabling to convert 20o0 hectares of rain-fed land into irrigation. The total cost to utilize lake water is US$ 2,756,729 and it was estimated that the project could recoup the investm.n. within 5 years which is quite reasonable in this water scarcity prone area.

关键词： Artificial recharge stream miangranLake groundwater Izeh Plain

Jacobian-free newton-Krylov subspace method with wavelet-based preconditioner for analysis of transient elastohydrodynamic lubrication problems with surface asperities

在线全文

学校读者我要写书评

暂无评论

Applied mathematics and mechanics(English Edition) 2020年第6期41卷 881-898页

作者： n.m.BUJURKE m.H.KAnTLI Departm.n. of mathematics Karnatak UniversityDharwad 580003India Departm.n. of mathematics Biluru Gurubasava Mahaswamiji Institute of TechnologyMudhol 587313India

This paper presents an investigation into the effect of surface asperities on the over-rolling of bearing surfaces in transient elastohydrodynamic lubrication(EHL) line contact. The governing equations are discretized by the finite difference method. The resulting nonlinear system of algebraic equations is solved by the Jacobian-free newtongeneralized m.n.mal residual(GmRES) from the Krylov subspace method(KSm). The acceleration of the GmRES iteration is accomplished by a wavelet-based *** profiles of the lubricant pressure and film thickness are obtained at each time step when the indented surface moves through the contact region. The prediction of pressure as a function of time provides an insight into the understanding of fatigue life of *** analysis confirms the need for the time-dependent approach of EHL problems with surface asperities. This method requires less storage and yields an accurate solution with much coarser grids. It is stable, efficient, allows a larger time step, and covers a wide range of parameters of interest.

关键词： transient elastohydrodynamic lubrication(EHL) surface roughness bearing newton-Krylov method generalized m.n.mal residual(GmRES) wavelet preconditioner