浅谈管磨机的分仓及其隔仓板的改造

管磨机隔仓板不但分隔研磨体,还具备控制物料通过量的功能。合理的结构决定过料能力。通过优化隔仓板结构,实施磨内合理分仓,使各仓球料比趋于更合理,球径针对性强,粉磨效率提高,既增产又节电。

Effect of high-intensity ultrasonic field on process of semi-continuous casting for AZ80 magnesium alloy billets

Under the high-intensity ultrasonic field,AZ80 magnesium alloy was semi-continuously cast.The effects of ultrasonic intensity on the as-cast microstructures and mechanical properties were investigated.The results show that the microstructures of the alloy cast under high-intensity ultrasonic field are fine and uniform,and the grains are equiaxed,rose-shaped or globular with an average size of 257μm.High-intensity field significantly decreases the grain size,changes the morphologies of theβ-Mg17Al12 phases and reduces their area fraction.It is also shown that a proper increase in ultrasonic intensity is helpful to obtain fine,uniform and equiaxed as-cast microstructures.The optimum ultrasonic parameters are that frequency is 20 kHz and ultrasonic intensity is 1 368 W.The mechanical tests show that the mechanical properties of the as-cast AZ80 magnesium alloy billets cast under ultrasonic field are greatly improved,and with increasing the ultrasonic intensity,the mechanical properties of the entire alloy billets are much higher and more uniform than those of the alloy without ultrasonic field.

Improved parameter selection method for mesoscopic numerical simulation test of direct tensile failure of rock and concrete

In order to numerically simulate the failure process of rock and concrete under uniaxial tension,an improved method of selecting the mechanical properties of materials was presented for the random mechanic parameter model based on the mesoscopic damage mechanics.The product of strength and elastic modulus of mesoscale representative volume element was considered to be one of the mechanical property parameters of materials and assumed to conform to specified probability distributions to reflect the heterogeneity of mechanical property in materials.With the improved property parameter selection method,a numerical program was developed and the simulation of the failure process of the rock and concrete specimens under static tensile loading condition was carried out.The failure process and complete stress-strain curves of a class of rock and concrete in stable fracture propagation manner under uniaxial tension were obtained.The simulated macroscopic mechanical behavior was compared with the available laboratory experimental observation,and a reasonable agreement was obtained.Verification shows that the improved parameter selection method is suitable for mesoscopic numerical simulation in the failure process of rock and concrete.

Enhanced magnetocaloric performances and tunable martensitic transformation in Ni_(35)Co_(15)Mn_(35-x)Fe_(x)Ti_(15) all-d-metal Heusler alloys by chemical and physical pressures

The solid-state magnetic cooling(MC)method based on the magnetocaloric effect(MCE)is recognized as an environmentally friendly and high-energy-efficiency technology.The search or design of suitable magnetic materials with large MCEs is one of the main targets at present.In this work,we apply the chemical and hydrostatic pressures in the Ni_(35)Co_(15)Mn_(35-x)Fe_(x)Ti_(15) all-d-metal Heusler alloys and systematically investigate their crystal structures,phases,and magnetocaloric performances experimentally and theoretically.All the alloys are found to crystallize in an ordered B2-type structure at room temperature and the atoms of Fe are confirmed to all occupy at sites Mn(B).The total magnetic moments decrease gradually with increasing Fe content and decreasing of volume as well.The martensitic transformation temperature decreases with the increase of Fe content,whereas increases with increasing hydrostatic pressure.Moreover,obviously enhanced magnetocaloric performances can also be obtained by applied pressures.The maximum values of magnetic entropy change and refrigeration capacity are as high as 15.61(24.20)J(kg K)^(−1) and 109.91(347.26)J kg^(−1) withΔH=20(50)kOe,respectively.These magnetocaloric performances are superior to most of the recently reported famous materials,indicating the potential application for active MC.

Feasibility analysis of high excess pressure cockpit using material substitution based on strain energy

The design concept of high excess pressure cockpit has been proposed as a solution to solve the ergonomics problems caused by cockpit environment.To address the contradiction among mass,economy,maneuverability and environment ergonomics,considering the composite advantages of high strength and lightweight,the feasibility analysis concept of high excess pressure cockpit based on material substitution is proposed in the paper.Based on the strain energy analysis on finite element model,the iteration design method of equal stiffness and lightening effect analysis on material substitution are presented,The weight reduction effect after material substitution can be evaluated intuitively by using equal stiffness curve.The calculation result of cockpit indicates that the lightening effect can reach 35.09%.Because of the complexity of cockpit design,bi-level optimization method is proposed and performed by means of the First-Order Radio algorithm.The research shows that the method can achieve good result.The feasibility of high excess pressure cockpit is studied from the aspect of the relationship between excess pressure and mass,and the research demonstrates that,due to the utilization of T300/4211 in place of 6061 alloy,the excess pressure of cockpit increases from 35 to 45 kPa,a 28.57%increase,while the cockpit mass is decreased by 12.56%.Thus,the contradiction among mass,economy and environment ergonomics can be coordinated,which can provide a reference for the design of high excess pressure cockpit.