Two-criterial evaluation of the limiting state of a cracked body under a nonsymmetric loading

1991 ◽  
Vol 23 (11) ◽  
pp. 1177-1184
Author(s):  
I. V. Orynyak ◽  
V. M. Torop
Keyword(s):  
Limiting State ◽  
Nonsymmetric Loading ◽  
Criterial Evaluation

Influence of the choice of wear criterion on the life of high speed machine manual taps

2020 ◽  
pp. 74-78
Author(s):  
A.E. Dreval
Keyword(s):  
Service Life ◽  
Structural Steel ◽  
Tool Life ◽  
High Speed ◽  
High Speed Steel ◽  
Parameter Dependence ◽  
Limiting State ◽  
Thread Cutting ◽  
Failure Life ◽  
High Speed Machine

The assessment of the limiting state of high-speed machine-manual taps in the processing of structural steel billets is considered. A general multi-parameter dependence is developed for calculating the criterion of allowable wear, which makes it possible to rationally use the tool life and normalize the cut amount during regrinding. Keywords thread cutting, tap, angle of the cutting part, criterion, high-speed steel, wear, failure, life, service life. [email protected]

Evaluating Heat Resistance of Mold Shells in Investment Casting

2019 ◽  
Vol 946 ◽  
pp. 678-683
Author(s):  
B.A. Kulakov ◽  
V.K. Dubrovin ◽  
O.M. Zaslavskaya
Keyword(s):  
Experimental Data ◽  
Heat Resistance ◽  
Experimental Method ◽  
Investment Casting ◽  
Electric Arc ◽  
Comparative Data ◽  
Evaluation Theory ◽  
Resistance Criterion ◽  
Criterial Evaluation

The paper describes the theory of developing the heat-resistance criterion for disposable ceramic molds exposed to poured metal, creating a computational and experimental method for computing the heat resistance by rapidly heating the mold by an electric arc, as well as analysis of comparative data on quartz, dinas, and electric-corundum molds from the standpoint of the developed criterial-evaluation theory. In this case, the heat resistance is of one-time character, as this mold sustains only a single casting. Computational and experimental data indicate a low heat resistance of β-quartz, making them non-recommendable for annealing and metal pouring if there is not supporting filler. Molds based on electric-corundum or dinas fillers are free of such drawbacks, with the latter being considerably cheaper. The use of tridymited dinas powders is effective after grinding the spent dinas lining of electric furnaces.

scholarly journals Design of plate and screw anchors in dense sand: failure mechanism, capacity and deformation

2019 ◽  
Vol 92 ◽  
pp. 16010
Author(s):  
Benjamin Cerfontaine ◽  
Jonathan Knappett ◽  
Michael Brown ◽  
Aaron Bradshaw
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Failure Mechanism ◽  
Progressive Failure ◽  
Vertical Direction ◽  
Shear Plane ◽  
Design Methods ◽  
Embedment Depth ◽  
Limiting State ◽  
Dense Sand

Plate and screw anchors provide a significant uplift capacity and have multiple applications in both onshore and offshore geotechnical engineering. Uplift design methods are mostly based on semi-empirical approaches assuming a failure mechanism, a normal and a shear stress distribution at failure and empirical factors back-calculated against experimental data. However, these design methods are shown to under- or overpredict most of the existing larger scale experimental tests. Numerical FE simulations are undertaken to provide new insight into the failure mechanism and stress distribution which should be considered in anchor design in dense sand. Results show that a conical shallow wedge whose inclination to the vertical direction is equal to the dilation angle is a good approximation of the failure mechanism in sand. This shallow mechanism has been observed in each case for relative embedment ratios (depth/diameter) ranging from 1 to 9. However, the stress distribution varies non-linearly with depth, due to the soil deformability and progressive failure. A sharp peak of normal and shear stress can be identified close to the anchor edge, before a gradual decrease with increasing distance along the shear plane. The peak stress magnitude increases almost linearly with embedment depth at larger relative embedment ratios. Although further research is necessary, these results lay the basis for the development of a new generation of design criteria for determining anchor capacity at the ultimate limiting state.

Logica di un sistema di sostegno alle imprese. La politica industriale italiana dal secondo dopoguerra a "Industria 2015"

2009 ◽  
pp. 89-113
Author(s):  
Fabrizio Traů
Keyword(s):  
Industrial Policy ◽  
State Intervention ◽  
State Aid ◽  
Limiting State ◽  
New Approach ◽  
Industrial Activities ◽  
The Universe ◽  
Over Time

- The paper aims at discussing the logic lying behind sixty years of industrial policy in Italy. It is argued that during this time State intervention has been characterised by the issue of an increasing number of laws (mostly persisting over time) devoted to specific objectives, but at the same time paralleled by a tendency towards the reduction of their selectivity through the widening (i.e. the loosening) of the boundaries of the universe of firms they were thought for. Such a logic seems to have made way in recent years for a relatively new approach, as stated in the program "Industria 2015", which has put at the centre of the stage the need for limiting State aid to a selected group of (horizontally identified) industrial activities. The paper also discusses some apparent shortcomings of this approach, emphasising that a risk for a new weakening of its selective logic is still at work.

Some problems of assessing the dynamic crack resistance of structural steels

2021 ◽  
Vol 18 (3) ◽  
pp. 428-435
Author(s):  
Vladimir I. SMIRNOV ◽  
◽  
Tatiana A. KNOPOVA ◽  
Sergey S. MAYER ◽  
◽  
...  
Keyword(s):  
Crack Resistance ◽  
High Speed ◽  
Dynamic Testing ◽  
Practical Importance ◽  
Dynamic Strength ◽  
Structural Steels ◽  
Dynamic Crack ◽  
Unstable Fracture ◽  
Structural Elements ◽  
Limiting State

Objective: Solving the problem of determining the conditions for the onset and development of unstable fracture, which is extremely important for the development of methods for calculating the limiting states of structural elements, improving the dynamic testing schemes of materials and classifying steels according to their ability to resist fracture. Methods: Analytical methods for assessing the limiting state of structural elements are used. Results: A brief overview of the available test methods for structural steels for dynamic strength and crack resistance is given. The experience accumulated by domestic and foreign practices in testing steels for strength and crack resistance under high-speed loading is analyzed. The disadvantages of the existing methods for assessing the indicators of dynamic strength and resistance to brittle fracture are indicated. Practical importance: It is shown that along with the traditional methods for assessing strength based on safety factors, it is necessary to develop and apply new methods for assessing the limiting state of structural elements, including by the criteria of crack resistance

Strengthening of Reinforced Concrete Beams by Carbon Fiber Composites

2018 ◽  
Vol 931 ◽  
pp. 379-384
Author(s):  
Yuri V. Ivanov ◽  
Yuri F. Rogatnev ◽  
Igor I. Ushakov
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Carbon Fiber Composites ◽  
Limiting State ◽  
Reinforced Plastics ◽  
Reinforced Beams ◽  
The Given

The paper considers the results of the experimental study of the reinforced concrete beams strengthened by carbon fiber reinforced plastics (the CFRP). Eight reinforced concrete beams of the 80x160 mm section and 1500 mm designed span have been manufactured and tested. The influence of the number of the CFRP layers (strengthening power) on bearing capacity and rigidity under the static loading of beams in the thirds of the span has been studied. The results obtained indicate the increase in bearing capacity of the reinforced beams from 24% up to 55% and the increase in rigidity by 45% for the commonly adopted limiting state, i.e. achieving ultimate deformations in concrete of the compressed zone). The paper underlines the need for using anchor devices in the form of U-shaped binders to ensure the efficiency of the given method of strengthening.

scholarly journals Application of the criterial approach for the choice of forming technology for rod fasteners

2018 ◽  
Vol 224 ◽  
pp. 01109
Author(s):  
Oleg Zhelezkov ◽  
Sergey Malakanov ◽  
Timur Galiahmetov
Keyword(s):  
Forming Technology ◽  
Production Processes ◽  
Rational Production ◽  
Criterial Evaluation

The article presents the results of the application of the developed complex criterial approach for evaluating the production processes of fasteners such as bolts with hexagon head. An estimation of two technologies for manufacturing bolts was made, based on the criterial evaluation, the most rational production variance was selected.

scholarly journals Energy cascade for highly anisotropic turbulence in the Stable Boundary Layer

2021 ◽  
Author(s):  
Federica Gucci ◽  
Lorenzo Giovannini ◽  
Dino Zardi ◽  
Nikki Vercauteren
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Stable Boundary Layer ◽  
Energy Cascade ◽  
Isotropic Case ◽  
Limiting State ◽  
Stable Boundary ◽  
Turbulence Anisotropy ◽  
Small Scales ◽  
Energy Exchanges

<p>The broad variety of phenomena occurring on multiple scales under stably stratified conditions and their complex interactions make it difficult to get a full description of the Stable Boundary Layer (SBL). Near-surface turbulence may be intermittent and highly anisotropic even at small scales. By studying the invariants of the anisotropy Reynolds stress tensor, it is possible to analyse the eddy kinetic energy distribution over the three components of the flow. Recent analyses of SBL turbulence data highlighted a prevalence of one-component limiting state of anisotropy. The causes of this particular limiting state are not fully understood, but there is evidence that submeso activity influences turbulence topology.<span> </span></p><p>This open question motivated the present work, that addresses the issue from the point of view of space dimensionality. In large-scale atmospheric and oceanic dynamics it is well known that turbulent motions may transfer energy both to the large and to the small scales, according to density stratification and rotation. These two properties act as constraints on the flow, giving it a 2D structure, and leading turbulence to be more complex than the homogeneous and isotropic case. For a SBL in low-wind speed conditions, atmospheric stratification might be very strong and we investigate if some of the peculiar characteristics of this regime might be related to a quasi-2D dynamics, with the occurrence of an inverse energy cascade, typical of 2D-like turbulence.</p><p>Energy exchanges across larger and smaller scales are studied by analysing the direction of the momentum flux with different methods, including a coarse-graining approach based on Large Eddy Simulation (LES) theory. The SnoHATS dataset was used to this purpose, where two vertically-separated horizontal arrays of sonic anemometers over the Plaine Morte Glacier (Switzerland) allowed the computation of the full three-dimensional velocity gradient. In order to fully characterize the energy exchanges according to different states of turbulence anisotropy, energy conversion processes between eddy kinetic and potential energy have also been considered and analysed at different heights. To this purpose, the dataset FLOSSII was used, providing turbulence measurements up to 30 m above a flat grass surface, often covered by snow.<span> </span></p><p>Results seem to suggest that turbulent kinetic energy in the SBL is distributed mainly in one component more as a consequence of wave-turbulence interactions than of development of 2D-like turbulence. This gives insights on mechanisms driving turbulence anisotropy that might be used to improve turbulence parameterizations in the SBL.</p>

scholarly journals MECHANICAL CHARACTERISTICS OF REINFORCED AND THREE-LAYER SHELLS BASED ON METAMATERIALS, TAKING INTO ACCOUNT OPERATIONAL DAMAGE

2021 ◽  
Vol 56 (6) ◽  
pp. 922-929
Author(s):  
E. V. Lomakin ◽  
S. A. Yurgenson ◽  
B. N. Fedulov ◽  
A. N. Fedorenko
Keyword(s):  
Residual Strength ◽  
Thin Shell ◽  
Mechanical Characteristics ◽  
Evaluation Criterion ◽  
Metamaterial Structure ◽  
Limiting State ◽  
Conventional Design ◽  
Aeronautical Engineering ◽  
Reinforced Shell

Abstract— The conventional design in aeronautical engineering is reinforced shell, which for most structures is a thin shell with a stringer set. This article compares the behavior of a conventional reinforced shell and a spaced shell metamaterial structure with a reinforced set using the example of a main airplane pressure bulkhead. The evaluation criterion is to ensure the required level of residual strength when the limiting state is reached.

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