Electromechanical dynamics analysis and simulation on rollforming equipment with both sides variable cross-section

Electromechanical dynamics analysis and simulation on a rollforming equipment with both sides variable cross-section are discussed in this study.The system includes mechanical parts and electromagnetism parts,and it is a strongly coupled electromechanical system.Based on a virtual work principle and given power,generalized forces of this system are obtained.By using Lagrange-Maxwell equations,a model of electromechanical dynamics is established.Differential equations of two-phase winding on d-q axis are obtained by Park transformation,which comes from three-phase winding equations on the A-B-C axis.This system is solved with the 4th order Runge-Kutta's method,and discrete solutions of all variables are obtained.Finally,by using Matlab language,the system is simulated.The results show that the proposed method works very well.

Integration of axiomatic design and theory of inventive problem solving for conceptual design

Axiomatic design (AD) and theory of inventive problem solving (TRIZ) are widely used in conceptual design. Both of them have limitations, however. We presented an integrated model of these two methods to increase the efficiency and quality of the problem solving process for conceptual design. AD is used for systematically defining and structuring a problem into a hierarchy. Sometimes, the design matrix is coupled in AD which indicates the functional requirements are coupled. TRIZ separation principles can be used to separate non-independent design parameters, which provide innovative solutions at each hierarchical level. We applied the integrated model to the heating and drying equipment of bitumen reproduction device. The result verifies that the integrated model can work very well in conceptual design.

Fabrication of ultrahigh density ZnO-Al_2O_3 ceramic composites by slip casting

The conditions of ZnO-Al2O3 aqueous suspensions and slip casting were optimized to obtain dense green compacts and further to obtain high density ZnO-Al2O3 ceramic composites.The Zeta potential of raw powders was measured.ZnO and Al2O3 powders have lower Zeta potential than-45 mV commonly at pH 8-10.3 with polyacrylic acid(PAA)added.The influence of pH and the mass fraction of the additives on the stability and fluidity of the suspensions added with PAA and polyethylene glycol(PEG) was investigated by experiments of viscosity and sedimentation.The suspensions have the lowest viscosity and the best stability at pH 9 with 0.2%PAA(mass fraction).The maximum density of green compacts is 66.6%of theoretical density(TD)with compacting and homogeneous green particles.An ultrahigh density sintered compact(>99.6%TD)could be obtained after pressureless sintering at 1 400℃for 2 h.

Work hardening of adhesively bonded pure copper single lap joints

To explain the reason why work hardening occurs in epoxy adhesive bonded zone of pure copper adherends after tensile shear strength testing, an elasto-plastic finite element model was established to analyze the effect of different adherends thickness of 2mm and 4mm on the shear strength as well as the level of work hardening in copper adherends of single lap joint. The numerical simulation results show that the axial or equivalent stress overrun the yield strength of the pure copper adherend is the main reason why the work hardening occurs on the bonded zone of the adherends after the shear strength testing. The elasto-plastic finite element simulation results are agreed with the experimental ones. The thicker its adherends are, the more serious the work hardening is.

Effect of Curing Procedure on the Properties of Copper-Powder-Filled Conductive Adhesives

By means of testing the shear strength with single lap joint, measuring electrical resistivity for cured products and the curing strain with strain gauges, the effect of cure parameters on the properties of HT1012 conductive adhesive filled with copper powder was investigated, and the residual stress in the conductive adhesives was also estimated. The experimental results show that the properties such as shear strength of the adhesives, electrical resistivity of products as well as the residual stress of cured HT 1012 copperfitted conductive adhesive were evidently affected by curing temperature and time. The diagrams of scanning electron microscopy （SEM） and Fourier transform infrared （FT-IR） were also used to determine the properties. The higher mechanical property was achieved under the condition of curing the adhesive 3 h at 60 ℃ as the density of the hydrogen links or linkages existed in the adhesive was relatively higher and the lower electrical resistivity occurred at 80 ℃.

Evaluation of properties for lubricant filter in diesel engines

The properties of lubricant filters in diesel engines directly affect operation of the lubricant system, and lubricant filters are apt to be impacted by many factors. Therefore, scientific and sensible methods evaluating the properties for lubricant filter diesel engines are necessary to monitor filter properties on line and dynamically. This paper applies ferrographic techniques and adopts sampling methods that oil specimens are synchronously obtained in front of and behind filter elements to monitor the filters of ISUZU DA-220 diesel engine in two FD50 forklifts. Results show that the combination of ferrographic techniques and above sampling methods is effective in analyzing the whole operating process of filters used in diesel engines. The service life and ruined type of filter can be estimated through the relationship between ferrographic readings in front and behind of filter and operation time. Furthermore, through a great deal of tests, a series of experimental curves of readings and time and characteristic parameters for filters used in different machines can be gained, which has guiding significance to the selection and maintenance of the filters. But because of the limitation of the ferrographic technique, the debris on the substrate prevents determination of sizes. It is difficult to judge accurately the size of debris that a filter can filter.

Effect of fillet on bi-adhesive bonded aluminum lap joints

The effect of fillet formed from structural adhesive differing in elastic modulus on the stress distribution along the length of bi-adhesive bonded single lap aluminum joints was studied under the condition of one adhesive or bi-adhesive arranged along the bondline by an elastic finite element model. The results obtained from the numerical simulation show that the fillet can reduce the peak value of stress obviously. It is not recommended to arrange a higher modulus adhesive with a lower one along the bondline for the peak stress may be maintained nearly the same. The lower the fillet formed by the elastic modulus adhesive is, the lower the stress concentration towards the end of a bonded lap joint is. It may be benefit to raise the shear strength of aluminum single lap joint.

Geometries and electronic structures of the hydrogenated diamond （100） surface upon exposure to active ions： A first principles study

To elucidate the effects of physisorbed active ions on the geometries and electronic structures of hydrogenated diamond films, models of HCO3, H3O^＋, and OH^- ions physisorbed on hydrogenated diamond （100） surfaces were constructed. Density functional theory was used to calculate the geometries, adsorption energies, and partial density of states. The results showed that the geometries of the hydrogenated diamond （100） surfaces all changed to different degrees after ion adsorption. Among them, the H3O^＋ ion affected the geometry of the hydrogenated diamond （100） surfaces the most. This is well consistent with the results of the calculated adsorption energies, which indicated that a strong electrostatic attraction occurs between the hydrogenated diamond （100） surface and H3O^＋ ions. In addition, electrons transfer significantly from the hydrogenated diamond （100） surface to the adsorbed H3O^＋ ion, which induces a downward shift in the HOMO and LUMO energy levels of the H3O^＋ ion. However, for active ions like OH^- and HCO3^, no dramatic change appears for the electronic structures of the adsorbed ions.

Device performance limit of monolayer SnSe_(2) MOSFET

Two-dimensional(2D)semiconductors are attractive channels to shrink the scale of field-effect transistors(FETs),and among which the anisotropic one is more advantageous for a higher on-state current(I_(on)).Monolayer(ML)SnSe_(2),as an abundant,economic,nontoxic,and stable two-dimensional material,possesses an anisotropic electronic nature.Herein,we study the device performances of the ML SnSe_(2) metal-oxide-semiconductor FETs(MOSFETs)and deduce their performance limit to an ultrashort gate length(L_(g))and ultralow supply voltage(V_(dd))by using the ab initio quantum transport simulation.An ultrahigh I_(on) of 5,660 and 3,145µA/µm is acquired for the n-type 10-nm-L_(g) ML SnSe_(2) MOSFET at V_(dd)=0.7 V for high-performance(HP)and low-power(LP)applications,respectively.Specifically,until L_(g) scales down to 2 and 3 nm,the MOSFETs(at V_(dd)=0.65 V)surpass I_(on),intrinsic delay time(τ),and power-delay product(PDP)of the International Roadmap for Device and Systems(IRDS,2020 version)for HP and LP devices for the year 2028.Moreover,the 5-nm-L_(g) ML SnSe_(2) MOSFET(at V_(dd)=0.4 V)fulfills the IRDS HP device and the 7-nm-L_(g) MOSFET(at V_(dd)=0.55 V)fulfills the IRDS LP device for the year 2034.

High-performance sub-10-nm monolayer black phosphorene tunneling transistors

Moore＇s law is approaching its physical limit. Tunneling field-effect transistors （TFETs） based on two-dimensional （2D） materials provide a possible scheme to extend Moore＇s law down to the sub-10-nm region owing to the electrostatic integrity and absence of dangling bonds in 2D materials. We report an ab initio quantum transport study on the device performance of monolayer （ML） black phosphorene （BP） TFETs in the sub-10-nm scale （6-10 nm）. Under the optimal schemes, the ML BP TFETs show excellent device performance along the armchair transport direction. The on-state current, delay time, and power dissipation of the optimal sub-10-nm ML BP TFETs significantly surpass the latest International Technology Roadmap for Semiconductors （ITRS） requirements for high- performance devices. The subthreshold swings are 56-100 mV/dec, which are much lower than those of their Schottky barrier and metal oxide semiconductor field-effect transistor counterparts.