scholarly journals DEM Simulation to Determine the Influence on the Experimental Results of Tests of Iron Pellets When the Dimensions of the Test Device Are Varied

2021 ◽  
Vol 10 (02) ◽  
pp. 65-80
Author(s):  
Yerko Aguilera-Carvajal ◽  
Yonathan Tapia Robledo ◽  
Sebastián Perez Cortes
Keyword(s):  
Experimental Results ◽  
Test Device ◽  
Dem Simulation

Vibration Suppression Device Having Variable Inertia Mass by MR-Fluid

2011 ◽  
Author(s):  
Taichi Matsuoka
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Vibration Suppression ◽  
Experimental Results ◽  
Inertia Force ◽  
Test Device ◽  
Piston Cylinder ◽  
New Type ◽  
Vibration Tests ◽  
Force Characteristics

Authors have proposed a new type of vibration suppression device that utilizes variable inertia mass by fluid which acts as a series inertia mass. The series inertia mass is proportional to not only square of a ratio between a diameter of a piston cylinder and a by-pass pipe, and also a density of the fluid. The resisting force characteristics in case of water or turbine oil were measured. To confirm the proposed theory and investigate effects of vibration control, vibration tests of frequency response and seismic response of one-degree-of-freedom system with the test device were carried out. The experimental results were compared with the calculated results, and the effects of vibration suppression are confirmed experimentally and theoretically. In this paper, in order to derive the effect of a variable inertia mass by using a magnet-rheological fluid, resisting force characteristics of the test device are measured in several cases of magnetic field. The orifice of the by-pass pipe can be changed in virtual, since some rare-earth magnets are installed around the by-pass pipe. It can be seen from experimental results that the inertia force is increasing as stronger magnetic fields. It is pointed out that the variable inertia mass can be derived since clustered magnetic particles in the by-pass pipe act as a virtual orifice under strong magnetic field. The relation between magnetic flux and variable inertia mass are estimated experimentally.

scholarly journals Experimental and Numerical Studies on the Direct Shear Behavior of Sand–RCA (Recycled Concrete Aggregates) Mixtures with Different Contents of RCA

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2909
Author(s):  
Yiming Liu ◽  
Shiqiang Huang ◽  
Lihua Li ◽  
Henglin Xiao ◽  
Zhi Chen ◽  
...  
Keyword(s):  
Shear Behavior ◽  
Recycled Concrete ◽  
Experimental Results ◽  
Coarse Grained ◽  
Shape Effect ◽  
Peak Strain ◽  
Direct Shear ◽  
Shear Tests ◽  
Dem Simulation ◽  
Direct Shear Tests

Recycled concrete aggregate (RCA) is a typical construction and demolition (C&D) material generated in civil engineering activities and has been widely used as the coarse-grained filler added to sand for roadbed fillings. The effect of RCA content on the mechanical behavior of sand–RCA mixtures is complicated and still not fully understood. To explore the effect of RCA content on the macroscale and microscopic behavior of the sand–RCA mixtures with various RCA contents, laboratory direct shear tests and numerical simulations using the 3D discrete element method were performed. Experimental direct shear tests on sand–RCA mixtures with different contents of RCA were first carried out. Numerical direct shear models were then established to represent the experimental results. The particle shape effect was also considered using a new realistic shape modeling method to model the RCA particles. Good agreement was observed between the DEM simulation and experimental results, verifying the ability of the numerical direct shear models to represent the direct shear behavior of sand–RCA mixtures. The macroscopic responses of both experimental and numerical tests showed that all samples presented an initial hardening followed by a post-peak strain softening. The peak-state friction angles increased with the RCA content for samples under the same vertical stress. The effect of RCA content on the microscopic behavior based on DEM simulation was also found. The microscopic properties of RCA–sand mixtures, such as coordination numbers, PDFs and contact force transformation features, were analyzed and related to the macroscopic results.

Effect of the operating parameter and grinding media on the wear properties of lifter in ball mills

2019 ◽  
Vol 234 (7) ◽  
pp. 1061-1074
Author(s):  
Zixin Yin ◽  
Yuxing Peng ◽  
Tongqing Li ◽  
Zhencai Zhu ◽  
Zhangfa Yu ◽  
...  
Keyword(s):  
Wear Rate ◽  
Ball Mill ◽  
Wear Behavior ◽  
Operating Parameter ◽  
Experimental Results ◽  
Ball Mills ◽  
Dem Simulation ◽  
Wear Process ◽  
Grinding Media ◽  
Mill Speed

The wear of lifter in ball mill directly affects the grinding efficiency and economic cost. However, how to evaluate the variation of wear process and predict the wear distribution of lifter is poorly developed. To this end, a laboratory-scale ball mill was used to evaluate the variation of wear process of the lifter in different milling conditions of mill speed, ball filling, grinding media size and shape. Besides, a wear prediction method was used to compare and validate the experimental results. The experimental results showed that the Abbott-Firestone curve can evaluate the lifter surface topography. The wear rate of the lifter specimen is increased first and then decreased with mill speed and grinding media size. Increasing ball filling will increase the wear rate, and the grinding media shape of ball has a maximum wear rate. The wear characteristics of the lifter specimen are consisting of impact pit, indentation, plastic deformation and scratch. Furthermore, the discrete element method (DEM) simulation showed that the wear behavior on the upper surface is higher than that on the side surface of the lifter. The DEM simulation with Archard wear model is an effective tool to investigate the wear distribution on the lifter, which is in good consistent with the wear behavior measured by the experiment.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

Multislice calculations of RHEED patterns from vicinal Si (001)

1993 ◽  
Vol 51 ◽  
pp. 1000-1001
Author(s):  
Scott Lordi
Keyword(s):  
Misorientation Angle ◽  
Incident Angle ◽  
Incident Beam ◽  
Experimental Results ◽  
Bragg Condition ◽  
Vicinal Surfaces ◽  
Kinematic Theory ◽  
Step Edges

Vicinal Si (001) surfaces are interesting because they are good substrates for the growth of III-V semiconductors. Spots in RHEED patterns from vicinal surfaces are split due to scattering from ordered step arrays and this splitting can be used to determine the misorientation angle, using kinematic arguments. Kinematic theory is generally regarded to be inadequate for the calculation of RHEED intensities; however, only a few dynamical RHEED simulations have been attempted for vicinal surfaces. The multislice formulation of Cowley and Moodie with a recently developed edge patching method was used to calculate RHEED patterns from vicinal Si (001) surfaces. The calculated patterns are qualitatively similar to published experimental results and the positions of the split spots quantitatively agree with kinematic calculations.RHEED patterns were calculated for unreconstructed (bulk terminated) Si (001) surfaces misoriented towards [110] ,with an energy of 15 keV, at an incident angle of 36.63 mrad ([004] bragg condition), and a beam azimuth of [110] (perpendicular to the step edges) and the incident beam pointed down the step staircase.

Effect of Stress and Relax Instructions on the Predictive Validity of a Test Device

1974 ◽  
Vol 7 (1) ◽  
pp. 46-50 ◽  
Author(s):  
Bruce W. Hall ◽  
T. Salvatore Tocco ◽  
Larry S. Schwartz
Keyword(s):  
Predictive Validity ◽  
Test Device
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