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Research on tool wear based on multi-scale simulation in high speed cutting Inconel 718

Fan Y. H., Wang T., Hao Z. P., Lan H., Cui R. R.

Archives of Civil and Mechanical Engineering

2018

Vol. 18, no. 3

928--940

Nickel-based superalloy Inconel718 has excellent properties such as good fatigue resistance, creep resistance, oxidation resistance and corrosion resistance. It has been widely used in aerospace industry. However, nickel-based superalloy is a kind of typical difficult-to process-material. The alloying elements which enhanced material exist in the form of high hardness compound (TiC, NbC and other interphase hard point). These high hardness compounds led to complicate cutting deformation, high cutting temperature, large cutting force and severe tool wear. According to the characteristics in cutting Inconel718 and the microstructure of cemented carbide tool, the wear properties and mechanism of carbide tool in cutting Inconel718 process are revealed by multi-scale analysis method. The main wear forms that wear debris peeled from the tool substrate are given and the evolution mechanism of tool wear caused by the crack in the cutting process is deeply studied.

Rapid NEGF-based calculation of ballistic current in ultra-short DG MOSFETs for circuit simulation

Hosenfeld F., Horst F.., Graef M., Farokhnejad A., Kloes A., Iniguez B., Lime F.

International Journal of Microelectronics and Computer Science

2016

Vol. 7, nr 2

65--72

Shrinking gate length in conventional MOSFETs leads to increasing short channel effects like source-to-drain (SD) tunneling. Compact modeling designers are challenged to model these quantum mechanical effects. The complexity lies in the set-up between time efficiency, physical model relation and analytical equations. Multi-scale simulation bridges the gap between compact models, its fast and efficient calculation of the device terminal voltages, and numerical device models which consider the effects of nanoscale devices. These numerical models iterate between Poisson- and Schroedinger equation which significantly slows down the simulation performance. The physicsbased consideration of quantum effects like the SD tunneling makes the non-equilibrium Green’s function (NEGF) to a stateof-the-art method for the simulation of devices in the sub 10 nm region. This work introduces a semi-analytical NEGF model for ultra-short DG MOSFETs. Applying the closed-form potential solution of a classical compact model, the model turns the NEGF from an iterative numerical solution into a straightforward calculation. The applied mathematical approximations speed up the calculation time of the 1D NEGF. The model results for the ballistic channel current in DG-MOSFETs are compared with numerical NanoMOS TCAD [1] simulation data. Shown is the accurate potential calculation as well as the good agreement of the current characteristic for temperatures down to 75 K for channel lengths from 6 nm to 20 nm and channel thickness from 1.5 nm to 3 nm.

The multi-scale FEM simulation of the drawing processes of high carbon steel

Milenin A., Muskalski Z., Wiewiórowska S., Kustra P.

Journal of Achievements in Materials and Manufacturing Engineering

2007

Vol. 23, nr 2

71-74

Purpose: The influence of cementite lamellas orientation on mechanical and technological properties of wire experimentally show up during investigation of drawing processes with change the direction of drawing between passes. The purpose of this paper is to develop a mathematical model of cementite and ferrite deformation during drawing processes and receive an information about transformation of a pearlitic structure of wire during drawing. Design/methodology/approach: The wire drawing processes was investigated in two levels - using the 2-dimensional rigid-plastic finite element method (macro-level) and modelling of a microstructure change (micro-level). In micro-level the process of deformation of representative volume element (RVE) is considered. The pearlitic colony deformation and stress-strain state in RVE is modelled with help of the FEM. Research limitations/implications: The influence of initial cementite lamellas orientation on triaxity factor and localization of deformation in micro-level is investigated. The numerical simulation is shown a maximal non-uniform deformation of pearlite phases for the canting positions of the cementite lamellas relative the drawing direction. Practical implications: The results of article will be helpful for a fundamental understanding of pearlitic deformation during development of high strength steel wires for tire cord applications. Originality/value: A new model of two-phase grain deformation for wire drawing is proposed. The new conception of simulation of the boundary conditions for the RVE is based on the penalty method and uses a solution of the problem on macro-level.