3-D DEM Validation using Steel Balls with Regular Packing Arrangements

2002 ◽  
Author(s):  
C. O'Sullivan ◽  
J. D. Bray ◽  
M. F. Riemer
Keyword(s):  
Regular Packing ◽  
Steel Balls

Effects of structural inhomogeneities on the steel balls resistance to loading

2020 ◽  
pp. 29-38
Author(s):  
O. B. Berdnik ◽  
I. N. Tsareva ◽  
L. A. Krivina ◽  
S. V. Kirikov ◽  
S. I. Gerasimov ◽  
...  
Keyword(s):  
Brittle Fracture ◽  
Bearing Steel ◽  
Metallographic Analysis ◽  
Structural Factors ◽  
Steel Shkh15 ◽  
Maximum Hardness ◽  
High Shock ◽  
Steel Balls ◽  
Plasticity Coefficient ◽  
Microstructure Of The Material

When conducting impact tests of protective glasses, nonunique cases of destruction of balls made of bearing steel ShKh15 were recorded. The causes of their destruction were determined. The state of the material was studied by fractographic and metallographic analysis, hardness and microhardness measurement. In the structure of the metal of all the balls, no critical defects were found such as flockens, shells and microcracks, but adverse factors were detected in the microstructure of the material, namely, the presence of fineneedle martensite with excessive carbides. It is established that the detected structural factors lead to liability to brittle fracture, an increase in the hardness of the material, a decrease in plasticity. To prevent brittle fracture of the balls and provide a reserve of plasticity of steel ShKh15 at high shock loads assessment calculations of ductility coefficient were made; and it was recommended to limit the maximum hardness of the material critical value HV=5.70 HPa (54 HRC), with the corresponding plasticity coefficient equal to 0.8.

Random impact FEM simulation of irregularly-shaped media for parametric study of vibratory surface enhancement

2021 ◽  
pp. 095440542199012
Author(s):  
Jing Zhang ◽  
Joselito Yam Alcaraz ◽  
Swee-Hock Yeo ◽  
Arun Prasanth Nagalingam ◽  
Abhay Gopinath
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Parametric Study ◽  
Thermal Loading ◽  
Low Cycle Fatigue ◽  
Fem Simulation ◽  
Surface Finishing ◽  
Aerospace Materials ◽  
Surface Enhancement ◽  
Steel Balls

Aerospace materials experience high levels of mechanical and thermal loading, high/low cycle fatigue, and damage from foreign objects during service, which can lead to premature retirement. Mechanical surface treatments of metallic components, for example, fan blades and blisks, are proven to improve fatigue life, improve wear resistance and avoid stress corrosion by introducing work hardening, compressive residual stresses of sub-surface, and surface finishing. Vibropeening can enhance aerospace materials’ fatigue life involving the kinetic agitation of hardened steel media in a vibratory finishing machine that induces compressive stresses into the component sub-layers while keeping a finished surface. Spherical steel balls are the most widely used shape among steel-based media and have been explored for decades. However, they are not always versatile, which cannot access deep grooves, sharp corners, and intricate profiles. Steel ballcones or satellites, when mixed with round steel balls and other steel media (diagonals, pins, eclipses, cones), works very well in such areas that ball-shaped media are unable to reach. However, a methodology of study the effect of irregularly-shaped media in surface enhancement processes has not been established. This paper proposes a finite element-based model to present a methodology for the parametric study of vibratory surface enhancement with irregularly-shaped media and investigates residual stress profiles within a treated area of an Inconel component. The methodology is discussed in detail, which involves a stochastic simulation of orientation, impact force, and impact location. The contrasting effects of a high aspect ratio, or an edge contact, as opposed to rounded and oblique contacts are demonstrated, with further analysis on the superposition of these effects. Finally, the simulation results are compared with actual residual stress measurements and was found to have a max percent difference of 34% up to 20 [Formula: see text]m below the media surface.

scholarly journals Study on the Influence of the Ball Material on Abrasive Particles’ Dynamics in Ball-Cratering Thin Coatings Wear Tests

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 668
Author(s):  
Gustavo Pinto ◽  
Andresa Baptista ◽  
Francisco Silva ◽  
Jacobo Porteiro ◽  
José Míguez ◽  
...  
Keyword(s):  
Aisi 304 ◽  
Thin Coatings ◽  
Iron And Steel ◽  
Test Configuration ◽  
Abrasive Particles ◽  
Aisi 52100 ◽  
Aisi 304 Steel ◽  
Aisi 52100 Steel ◽  
Steel Balls ◽  
Particles Dynamics

Micro-abrasion remains a test configuration hugely used, mainly for thin coatings. Several studies have been carried out investigating the parameters around this configuration. Recently, a new study was launched studying the behavior of different ball materials in abrasive particles’ dynamics in the contact area. This study intends to extend that study, investigating new ball materials never used so far in this test configuration. Thus, commercial balls of American Iron and Steel Institute (AISI) 52100 steel, Stainless Steel (SS) (AISI) 304 steel and Polytetrafluoroethylene (PTFE) were used under different test conditions and abrasive particles, using always the same coating for reference. Craters generated on the coated samples’ surface and tracks on the balls’ surface were carefully observed by Scanning Electron Microscopy (SEM) and 3D microscopy in order to understand the abrasive particles’ dynamics. As a softer material, more abrasive particles were entrapped on the PTFE ball’s surface, generating grooving wear on the samples. SS AISI 304 balls, being softer than the abrasive particles (diamond), also allowed particle entrapment, originating from grooving wear. AISI 52100 steel balls presented particle dynamics that are already known. Thus, this study extends the knowledge already existing, allowing to better select the ball material to be used in ball-cratering tests.

Checking the Surface Contour of Higher Order Deep Aspherics Using Precision Steel Balls

1985 ◽  
Vol 14 (2) ◽  
pp. 69-71
Author(s):  
H. S. Singh ◽  
G. K. Sharma ◽  
G. P. Dimri
Keyword(s):  
Higher Order ◽  
Surface Contour ◽  
Steel Balls

scholarly journals Friction and Wear of Oxide Scale Obtained on Pure Titanium after High-Temperature Oxidation

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3764
Author(s):  
Krzysztof Aniołek ◽  
Adrian Barylski ◽  
Marian Kupka
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
High Temperature Oxidation ◽  
Friction And Wear ◽  
High Carbon Steel ◽  
Oxide Films ◽  
Oxidation Temperature ◽  
Temperature Oxidation ◽  
Wear Ratio ◽  
Steel Balls

High-temperature oxidation was performed at temperatures from 600 to 750 °C over a period of 24 h and 72 h. It was shown in the study that the oxide scale became more homogeneous and covered the entire surface as the oxidation temperature increased. After oxidation over a period of 24 h, the hardness of the produced layers increased as the oxidation temperature increased (from 892.4 to 1146.6 kgf/mm2). During oxidation in a longer time variant (72 h), layers with a higher hardness were obtained (1260 kgf/mm2). Studies on friction and wear characteristics of titanium were conducted using couples with ceramic balls (Al2O3, ZrO2) and with high-carbon steel (100Cr6) balls. The oxide films produced at a temperature range of 600–750 °C led to a reduction of the wear ratio value, with the lowest one obtained in tests with the 100Cr6 steel balls. Frictional contact of Al2O3 balls with an oxidized titanium disc resulted in a reduction of the wear ratio, but only for the oxide scales produced at 600 °C (24 h, 72 h) and 650 °C (24 h). For the ZrO2 balls, an increase in the wear ratio was observed, especially when interacting with the oxide films obtained after high-temperature oxidation at 650 °C or higher temperatures. The increase in wear intensity after titanium oxidation was also observed for the 100Cr6 steel balls.

THE STRUCTURE OF AGGREGATES AND THE MOLECULAR KINEMATICS OF THE VISCOSITY OF A BERNAL LIQUID

1964 ◽  
Vol 42 (2) ◽  
pp. 304-320 ◽  
Author(s):  
F. W. Smith
Keyword(s):  
Coordination Number ◽  
Free Volume ◽  
Activation Volume ◽  
Molecular Volume ◽  
3 Dimensional ◽  
Theory Of Liquids ◽  
Kinetic Pressure ◽  
Steel Balls ◽  
Set Of Points ◽  
Structure Of Aggregates

The structure of 3-dimensional aggregates is discussed as a set of points on which graphs are constructed. By constructing the Voronoi honeycomb (Dirichlet regions) for the points and applying a small "irregularizing transformation", a "simplicial graph" and a "primitive coordination number" (whose value is close to 14 for all aggregates) can be defined universally for both regular and irregular aggregates. Recent studies of the geometry of irregular aggregates (of steel balls, crystal grains, etc.) are reviewed. The theory of liquids of J. D. Bernal is discussed and the simplicial graph is used to show that the "activation volume" of a Bernal liquid is about one-tenth of the molecular volume. The kinematics of flow of aggregates is discussed in terms of their graphs and in terms of a process of "volume exchange"—the production and destruction of free volume. Using these concepts, an equation is derived for the viscosity of a Bernal liquid as a product of five terms expressing respectively the kinematic, stoichiometric, kinetic, pressure-dependent, and shear-dependent factors.

scholarly journals On the mechanism of boundary lubrication. II. Wear prevention by addition agents

1940 ◽  
Vol 177 (968) ◽  
pp. 103-118 ◽  
Keyword(s):  
High Pressures ◽  
Preceding Paper ◽  
Accurate Method ◽  
Polar Compounds ◽  
Experimental Conditions ◽  
Group V ◽  
Highly Sensitive ◽  
Local Pressures ◽  
Steel Balls ◽  
Long Chain

If two metal surfaces slide over each other in the presence of a lubricant and under high load, high pressures and temperatures prevail a t those isolated spots which actually carry the load, leading to wear and possibly to breakdown. The action of wear preventing agents under these conditions has been studied in detail and it has been found that such agents are effective through their chemical polishing action, by which the load becomes distributed over a larger surface and local pressures and temperatures are decreased. Especially effective are compounds containing phosphorus or other elements of group V of the periodic system. These have been found to form a metal phosphide or homolog on the surface which is able to alloy with the metal surface, lowering its melting point markedly, and by this action aiding greatly in maintaining a polish. The wear experiments were carried out with a highly sensitive and accurate method which uses metal-plated steel balls as its sliding elements. Under the experimental conditions additions of 1.5% triphenyl phosphine or triphenyl arsine in white oil gave wear prevention factors of 7.2 and 12.2 respectively (relative to pure white oil). A further addition of 1% of a long chain polar compound is able to double the wear prevention factor obtained with the polishing agents and wear prevention factors as high as 17.6 have been observed. The specifically physical action of the long-chain polar compounds is discussed in the preceding paper.

Detection of fungal decay by high-energy multiple impact (HEMI) testing

Holzforschung ◽  
2006 ◽  
Vol 60 (2) ◽  
pp. 217-222 ◽  
Author(s):  
Christian Brischke ◽  
Christian Robert Welzbacher ◽  
Andreas Otto Rapp
Keyword(s):  
Structural Changes ◽  
Brown Rot ◽  
High Energy ◽  
White Rot ◽  
Fungal Decay ◽  
Highly Correlated ◽  
Thermally Modified Wood ◽  
Impact Milling ◽  
Multiple Impact ◽  
Steel Balls

Abstract The suitability of a previously described high-energy multiple impact (HEMI) test for the detection of early fungal decay was examined. The HEMI test characterises the treatment severity of thermally modified wood by stressing the treated material by thousands of impacts of pounding steel balls. This method differentiates between heat treatment intensities, which are manifest as structural changes in the wood. Similar changes in wood structure are known for wood decayed by fungi. Pine (Pinus sylvestris L.) decayed by brown rot and beech (Fagus sylvatica L.) decayed by white rot were tested. Mass loss caused by fungal decay and resistance to impact milling (RIM) determined in HEMI tests were found to be highly correlated. Testing of non-degraded pine, beech, and ash (Fraxinus exelsior L.) showed only marginal effects of wood density on RIM. Furthermore, annual ring angles and RIM of spruce (Picea abies Karst.) were not correlated. Accordingly, the detection of RIM reduction in decayed wood is not masked by variations in density and orientation of the annual rings. Previous results showed no adverse effects of weathering on RIM. Thus, the detection of fungal decay with HEMI tests is feasible not only for laboratory purposes, but also for wood in outdoor applications that has already undergone weathering.

scholarly journals The hardening of metals by rotating magnetic fields

1931 ◽  
Vol 130 (814) ◽  
pp. 514-523 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Work Hardening ◽  
Rotating Magnetic Fields ◽  
Hardening Process ◽  
Hard Steel ◽  
Steel Balls ◽  
Hardened Condition

In a previous paper by the author experiments were described in which the hardness of various metals was increased by rotating them in a magnetic field. It had been observed that metals in a work-hardened condition, and in particular hard steel which had been super-hardened by the “Cloudburst” process of bombardment with steel balls, exhibit a propensity to become still harder by a process of ageing, the spontaneous increase of hardness commencing with the termination of the work-hardening process, and contiuning during a period of several hours or days.

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