scholarly journals Surface Remelting of Mold Inserts Made of NC11 Steel

2020 ◽  
Vol 4 (1) ◽  
pp. 9-15
Author(s):  
Andrzej Stanisław Trytek ◽  
Mirosław Tupaj ◽  
Ján Majerník ◽  
Štefan Gašpár ◽  
Wiktoria Zbyrad-Kołodziej ◽  
...  
Keyword(s):  
Abrasive Wear ◽  
Optical Microscopy ◽  
Heat Affected Zone ◽  
Steel Surface ◽  
The State ◽  
State Of Stress ◽  
The Press ◽  
Refractory Bricks ◽  
Press Molding

In the study presented in this paper, the effect of a concentrated heat stream on geometry, microstructure, and hardness of superficial remeltings on NC11 steel is examined. The material is used for disposable mold inserts exposed to intensive abrasive wear in the course of the press-molding of hard aggregate stampings for refractory bricks. As a result of local remelting, the hardness of the steel surface increased and its microstructure was altered. Macro- and microstructure of the remelted areas was examined with the use of optical microscopy and measurements of remelting area geometry were carried out for different parameters of the remelting process. Hardness measurements were taken in the remelting area and in the heat-affected zone. The state of stress in the material before remelting and in the remelted area was also evaluated.

scholarly journals Half-plane contacts subject to remote tension

2021 ◽  
pp. 030932472098844
Author(s):  
Nils Cwiekala ◽  
David A Hills
Keyword(s):  
Contact Problem ◽  
Half Plane ◽  
Asymptotic Form ◽  
Fretting Fatigue ◽  
The State ◽  
Partial Slip ◽  
Practical Relevance ◽  
Plane Contact ◽  
State Of Stress ◽  
Plane Contact Problem

The state of stress present in an elastic half-plane contact problem, where one or both bodies is subject to remote tension has been investigated, both for conditions of full stick and partial slip. The state of stress present near the contact edges is studied for different loading scenarios in an asymptotic form. This is of practical relevance to the study of contacts experiencing fretting fatigue, and enables the environment in which cracks nucleate to be specified.

scholarly journals Effect of the Rock Stress on the Water Jet Cutting Performance

2021 ◽  
Author(s):  
Battista Grosso ◽  
Valentina Dentoni ◽  
Augusto Bortolussi
Keyword(s):  
Numerical Models ◽  
Step Function ◽  
Water Jet ◽  
The State ◽  
Cutting Performance ◽  
Lagrangian Analysis ◽  
State Of Stress ◽  
Water Jet Cutting ◽  
Cutting Rate ◽  
Available Technology

AbstractUnderground quarrying is rarely adopted for granite extraction due to the difficulties in the implementation of traditional technologies (drilling and explosive). As alternative to drilling and explosive, the combination of diamond wire and water jet seems to be the most promising available technology. The cutting performance achievable with the water jet technology depends on the operative parameters, the material characteristics and the state of stress within the rock massif. To assess the effect of the state of stress on the cutting rate, laboratory tests have been performed with an oscillating water jet machine on granite samples subjected to a static load. The stress distribution in the layer of rock to be removed has been evaluated by numerical simulation with the FLAC code (Fast Lagrangian Analysis of Continua). The correlation between the results of the cutting tests and the numerical models of the rock samples has been inferred. Starting from a conceptual model, which theoretically describes the relationship between the cutting rate and the stress, a step function was defined that indicates the ranges of stress where predefined values of the cutting rate are workable.

scholarly journals Sub-Level Stoping in an Underground Limestone Quarry: An Analysis of the State of Stress in an Evolutionary Scenario

2016 ◽  
Vol 61 (1) ◽  
pp. 199-216 ◽  
Author(s):  
Marilena Cardu ◽  
Sergio Dipietromaria ◽  
Pierpaolo Oreste
Keyword(s):  
Numerical Models ◽  
The State ◽  
In Situ Tests ◽  
Future Scenario ◽  
Limestone Quarry ◽  
Geomechanical Properties ◽  
State Of Stress ◽  
Upper Level ◽  
Pillar Structure

Abstract The aim of this study was to evaluate the state of stress of a „voids-pillar“ structure excavated by means of the sub-level stoping method in an underground limestone quarry near Bergamo (Italy). Both the current structure of the quarry (i.e. the rooms exploited till now) and a possible future scenario were analysed using the (FDM) FLAC 2D code. The quarry has been in operation since 1927; at present, exploitation is carried out underground via the sub-level stoping method. Exploitation involves two levels, with 5 rooms on the upper level and 9 rooms on the lower level. After analysing data obtained from laboratory and in situ tests carried out on rock samples and natural discontinuities, the geomechanical properties of the medium, knowledge of which is essential in order to establish the parameters that must be included in the numerical model, were evaluated. The implementation of three numerical models made it possible to study both the present conditions of quarry exploitation and the evolution of the exploited rooms, as well as a possible expansion involving a third level of rooms. Using the results obtained regarding the stress-strain present in the pillars, a potential change in room geometry was proposed aimed at reducing the stress state inside the pillars, decreasing plasticity and increasing overall quarry safety.

Experimental Determination of the Two-Dimensional State of Stress and the Orthotropic Elasticity Coefficients for Coatings

1990 ◽  
Vol 203 ◽  
Author(s):  
Richard J. Farris ◽  
M. A. Maden ◽  
K. Tong
Keyword(s):  
Elastic Constants ◽  
Physical Property ◽  
The State ◽  
Normal Stresses ◽  
Free Standing ◽  
Vibrationally Excited ◽  
Plane Shear ◽  
Plane Normal ◽  
State Of Stress ◽  
The One

ABSTRACTThe state of stress for a uniform coating away from the edges reduces to that of plane stress, two in-plane normal stresses, and an in-plane shear stress. For this state, the interface between the coating and the substrate is totally stress free. Since the substrate and the coating are not interacting mechanically, an internal section of the substrate can be removed creating a tensioned drum-like membrane without altering the stress state. Holographic interferometry of vibrationally excited membranes is used to evaluate the stress. Using this technique, up to thirty vibrational modes can be obtained. This high degree of redundancy enables one to determine the one shear and two normal stresses that act in the plane of the coating. The only physical property requires is the coating density. The density is obtained from commonly reported literature values. Simple variations on the membrane vibration scheme, e.g., cutting the membrane to create a uniaxially tensioned ribbon, enables one to determine the in-plane Poisson's ratio and shearmodulus.In separate but related experiments on commercially made free-standing films with residual orientation, the above techniques, combined with special free and axially constrainedcompressibility experiments should enable all of the Poisson's ratios and elasticmoduli for an orthotropic material (nine elastic constants) to be determined. Methods for measuring the state of stress and the elastic constants are required to predict the state of stress in complex coating geometries.

scholarly journals Contested Numbers: Census Controversies and the Press in 1960s Nigeria

2021 ◽  
pp. 1-19
Author(s):  
Gerardo Serra ◽  
Morten Jerven
Keyword(s):  
Public Sphere ◽  
Political Culture ◽  
Cultural History ◽  
The State ◽  
Population Census ◽  
The Public ◽  
The Press ◽  
Distribution Of Resources ◽  
The Public Sphere

Abstract This article reconstructs the controversies following the release of the figures from Nigeria's 1963 population census. As the basis for the allocation of seats in the federal parliament and for the distribution of resources, the census is a valuable entry point into postcolonial Nigeria's political culture. After presenting an overview of how the Africanist literature has conceptualized the politics of population counting, the article analyses the role of the press in constructing the meaning and implications of the 1963 count. In contrast with the literature's emphasis on identification, categorization, and enumeration, our focus is on how the census results informed a broader range of visual and textual narratives. It is argued that analysing the multiple ways in which demographic sources shape debates about trust, identity, and the state in the public sphere results in a richer understanding of the politics of counting people and narrows the gap between demographic and cultural history.

1. Text of United States Note to the Far Eastern Commission on a Japanese Peace Treaty, Released to the Press, November 24, 1950.

1951 ◽  
Vol 5 (1) ◽  
pp. 242-243
Keyword(s):  
United States ◽  
The United States ◽  
The State ◽  
United States Government ◽  
Peace Treaty ◽  
General Statement ◽  
The Press ◽  
States Government ◽  
Far Eastern

There is given below a brief general statement of the type of treaty envisioned by the United States Government as proper to end the state of war with Japan. It is stressed that this statement is only suggestive and tentative, and does not commit the United States Government to the detailed content or wording of any future draft. It is expected that after there has been an opportunity to study this outline, there will be a series of informal discussions designed to elaborate on it and make clear any points which may be obscure at first glance.

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