scholarly journals Integral assessment of stress-defomated condition of metal structures of machines under the action of static and dynamic loads

2021 ◽  
pp. 188-196
Author(s):  
Ivan Nazarenko ◽  
◽  
Mykola Kuzminets ◽  
Oleg Dedov ◽  
Igor Zalіsko ◽  
...  
Keyword(s):  
Equations Of Motion ◽  
Steel Structures ◽  
Theory Of Elasticity ◽  
Dynamic Loads ◽  
Simultaneous Action ◽  
Structural Element ◽  
Metal Structures ◽  
Method Of Calculation ◽  
Definition Of ◽  
Integral Assessment

The article considers a system that combines the influence of static on dynamic loads on the example of the support-rotary circuit of a truck construction crane. The position of the system and its elements with the highest loads is revealed, the method of creating steel structures is investigated, each element, depending on the average load, experiences a stress-strain state. The basic laws of the theory of elasticity and plasticity were used to build a calculated mathematical model of the loaded support-rotary circuit. Equations of motion were compiled taking into account the behavior of structural elements and the machine as a whole under the simultaneous action of different loads. The calculation scheme was taken in the form of a structure consisting of rods rigidly connected to each other in nodes. As a method of calculation the method of finite elements with definition of displacements (deformations), efforts (stresses) in nodes of a grid of constructive elements of a design of a basic-rotary contour is applied. The stress distribution in each structural element depending on the type of load was obtained. This distribution allowed to choose rational parameters of a design in each its section. The proposed approach allowed to create a solid structure that provides reliability and economy of material. Thus, the results obtained allowed to fully analyze and decide on the simultaneous provision of strength, rigidity and minimum material consumption of the structure.

METHODOLOGICAL APPROACHES TO SEARCH FOR RESERVES OF DECREASING COSTS IN THE BRANCHES OF AGRICULTURAL PRODUCTION

2019 ◽  
Keyword(s):  
Agricultural Production ◽  
Raw Materials ◽  
Cost Calculation ◽  
Cattle Breeding ◽  
Method Of Calculation ◽  
Prime Cost ◽  
Dairy Cattle Breeding ◽  
Methodological Approaches ◽  
Definition Of ◽  
Qualitative Characteristics

In this article approaches to search for reserves of decrease in cost of agricultural production are considered. The methods of cost calculation of dairy cattle breeding products used at the studied enter-prise are analysed, short characteristic of the standard method offered by the Ministry of Agriculture is given, and calculations of alternative options are also carried out. Today creation of accounting of a production unit is very important so that not only weight units must be considered in it, but also the quali-tative structure of products must be reflected. Definition of qualitative characteristics and technological properties by production of milk which depend on use purposes can be an example. The raw materials consumption on a unit of production and its quality and also firmness of storage depends on technologi-cal properties of milk. At calculation of prime cost taking into account qualitative characteristics for cal-culation milk in terms of basic fat content undertakes. The method of calculation of prime cost consider-ing qualitative characteristics is the most expedient as prime cost of 1 c of milk unlike the operating tech-nique is lower. In the article analytical methods of reserves calculation for decrease in prime cost taking into account various factors are proved. The revealed reserves will allow an enterprise to expand its in-vestment opportunities in the future, they will give an additional incentive of modernization of the worn-out machinery and equipment in branches of agriculture.

scholarly journals Comparison of Neural Networks and Logistic Regression in Assessing the Occurrence of Failures in Steel Structures of Transmission Lines

2016 ◽  
Vol 10 (1) ◽  
pp. 11-26
Author(s):  
A.C.G Bissacot ◽  
S.A.B Salgado ◽  
P.P Balestrassi ◽  
A.P Paiva ◽  
A.C Zambroni Souza ◽  
...  
Keyword(s):  
Neural Networks ◽  
Logistic Regression ◽  
Transmission Lines ◽  
Steel Structures ◽  
Roc Curves ◽  
Operating Voltage ◽  
Operating Characteristics ◽  
Metal Structures ◽  
Land Type ◽  
Classic Technique

In this work, we evaluate the probability of falling metal structures from transmission lines. It is our objective to extract knowledge about which variables influence the mechanical behavior of the operating lines and can be used to diagnose potential falling towers. Those pieces of information can become a basis for directing the investments of reinforcement structures, avoiding the occurrence of long turn offs and high costs as a consequence of damage to towers of transmission lines. The results are obtained using the history of 181 metal structures currently in operation in the state of Paraná/Brazil. For the classification of transmission lines susceptible to failures it is proposed to identify the most likely lines considering the following parameters: operating voltage, wind and relief of the region, air masses, temperature, land type, mechanical capacity, function and foundation structure. The classic technique of classifying binary events used in this type of problem is the logistic regression (LR). The more recent technique for classification, using Artificial Neural Networks (ANN) can also be applied. The results are compared through the area under receiver operating characteristics (ROC) curves.

scholarly journals Resource justification of the financial security of Russian industrial organizations

2020 ◽  
Vol 8 (3) ◽  
pp. 21-25
Author(s):  
Oksana Ivanova
Keyword(s):  
Industrial Production ◽  
Financial Stability ◽  
Financial Risk ◽  
Economic Security ◽  
Financial Security ◽  
Data Set ◽  
Current Time ◽  
Industrial Organizations ◽  
Definition Of ◽  
Integral Assessment

One of the components of the positions of strengthening the competitiveness and financial independence of Russian industrial organizations is the definition of interrelated compositions in the context of the national and economic security of the country. Verification of the information flow of a data set is to a large extent a tool base for determining key facts in the event of challenges and threats. Therefore, the main goal of the work is to build an information base and mathematically determine the relationship between individual indicators to establish the level of financial security of Russian industrial production. Dialectical research methods determine the fundamental foundations of the issue being disclosed. The proposed methodology for the integral assessment of financial security reflects individual positions in the system of assessing financial risk and combines both positive and negative features of the development of industrial production. As a result of the multi-criteria assessment and the calculated integral indicator, the article singles out groups for assessing the financial risk of industrial organizations, which is the basis for assessing the competitiveness and financial stability both at the current time and in the forecast future.

scholarly journals Mathematical Modeling of Impact of Possible Shock Dynamic Loads on the Modern Composite Materials

2019 ◽  
Vol 224 ◽  
pp. 02012
Author(s):  
Eugenе Sosenushkin ◽  
Oksana Ivanova ◽  
Elena Yanovskaya ◽  
Yuliya Vinogradova
Keyword(s):  
Composite Materials ◽  
Friction Force ◽  
Equations Of Motion ◽  
Elastic Fiber ◽  
Dynamic Loads ◽  
Friction Forces ◽  
Absolute Value ◽  
A Value ◽  
The Absolute ◽  
The Impact

In this paper, we study the dynamic processes in materials reinforced with fibers, that can be represented as composite rods. There has been developed a mathematical model of wave propagation under the impact of a shock pulse in semi-infinite composite rods. It is believed that the considered composite rod consists of two layers formed by simpler rods of different isotropic materials with different mechanical properties. The cross sections of such rods are considered to be constant and identical. When such composite materials are impacted by dynamic loads, a significant part of the energy is dissipated due to the presence of friction forces between the contact surfaces of the rods. In this regard, we study the propagation of waves in an elastic fiber-rod, the layers of which interact according to Coulomb law of dry friction. The case of instantaneous excitation of rods by step pulses is investigated. The blow is applied to a rod made of a harder material. In the absence of slippage, the friction force gets a value not exceeding the absolute value of the limit. In the absence of slippage, the friction force takes a value not exceeding the absolute value of the limit. Let us consider the value of the friction force constant. Normal stresses and velocities satisfy the equations of motion and Hooke’s law. The problem statement results in the solution of inhomogeneous wave equations by the method of characteristics in different domains, which are the lines of discontinuities of the solution. Solutions are found in all constructed domains. On the basis of the analysis of the obtained solution, qualitative conclusions are made and curves are constructed according to the obtained ratios. From the found analytical solution of the problem it is possible to obtain ratios for stresses and strain rates in composite rods and composite materials.

scholarly journals Experimental study of zone of yield strength on corroded construction steel specimens for reuse

2019 ◽  
Vol 279 ◽  
pp. 02009
Author(s):  
Antonio Shopov ◽  
Borislav Bonev
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Experimental Study ◽  
Yield Strength ◽  
Structural Changes ◽  
Steel Structures ◽  
Strain Diagram ◽  
Lower Yield ◽  
Structural Element ◽  
Lower Yield Strength

Zone of yield strength is a part of stress-strain diagram on steel. In this zone is located an upper and lower yield strength points. These points are important for calculation and design of steel structures elements. When a structural element is corroded, its mechanical properties are changed i.e. changes the geometric characteristics, superficial defects appear and leads to structural changes of material. The facts unambiguously determine that in order to decide whether or not the corrosion element can be reuse, it is necessary to study the material and to determine the new values at the yield strength points. In order to legally make the necessary calculation in sizing and to judge for its reuse. The report studies a zone of yield strength on steel elements with corrosion. Experimental data was obtained, then processed using the stochastic method of processing empirically obtained data, and it was determined with sufficient probability the values to be used for calculation and design in practice.

Structural Steel Performance Following Severe Earthquake Loading

2011 ◽  
Vol 25 (31) ◽  
pp. 4149-4153
Author(s):  
W. G. Fergusona ◽  
C. K. Seal ◽  
M. A. Hodgson ◽  
G. C. Clifton
Keyword(s):  
Plastic Strain ◽  
Structural Steel ◽  
Central Business District ◽  
Steel Structures ◽  
Earthquake Loading ◽  
Structural Elements ◽  
Steel Buildings ◽  
Structural Element ◽  
Tension And Compression ◽  
Business District

The second Christchurch earthquake on February 22, 2011, Magnitude 6.35, generated more intense shaking in the Central Business District than the September 4, 2010 Darfield earthquake, Magnitude 7.1. The second earthquake was closer to the CBD and at shallow depth, resulting in peak ground accelerations 3 times higher. There was significant failure of unreinforced masonry buildings and collapse of a few reinforced concrete buildings, leading to loss of life. Steel structures on the whole performed well during the earthquake and the plastic, inelastic deformation was less than expected given the strength of the recorded ground accelerations. For steel buildings designed to withstand earthquake loading, a design philosophy is to have some structural elements deform plastically, absorbing energy in the process. Typically elements of beams are designed to plastically deform while the columns remain elastic. In the earthquake some of these elements deformed plastically and the buildings were structurally undamaged. The question which then arises is; the building may be safe, but will it withstand a further severe earthquake? In other words how much further plastic work damage can be absorbed without failure of the structural element? Previous research at Auckland on modern structural steel, where the steel was prestrained various levels, to represent earthquake loading, the toughness was determined, as a function of prestrain for the naturally strain-aged steel. Further research, on the same steel, investigated life to failure for cyclic plastic straining in tension and compression loading at various plastic strain amplitudes. This work has shown that provided the plastic strain in the structural element is in the range 2 – 5% the steel will still meet the relevant NZ Standards. To determine the remaining life the plastic strain must be determ ined then the decision made; to use the building as is, replace the structural element or demolish.

Simulation of Flexible-Link Manipulators With Inertial and Geometric Nonlinearities

1995 ◽  
Vol 117 (1) ◽  
pp. 74-87 ◽  
Author(s):  
Chris Damaren ◽  
Inna Sharf
Keyword(s):  
Space Shuttle ◽  
Equations Of Motion ◽  
Theory Of Elasticity ◽  
Dynamics Simulation ◽  
The Finite Element Method ◽  
Flexible Link ◽  
Geometric Nonlinearities ◽  
Geometric Stiffening ◽  
Inertial Nonlinearities ◽  
Function Selection

Several important issues relevant to modeling of flexible-link robotic manipulators are addressed in this paper. First, we examine the question of which inertial nonlinearities should be included in the equations of motion for purposes of simulation. A complete model incorporating all inertial terms that couple rigid-body and elastic motions is presented along with a rational scheme for classifying them. Second, the issue of geometric nonlinearities is discussed. These are terms whose origin is the geometrically nonlinear theory of elasticity, as well as the terms arising from the interbody coupling due to the elastic deformation at the link tip. Accordingly, a general way of incorporating the well-known geometric stiffening effect is presented along with several schemes for treating the elastic kinematics at the joint interconnections. In addition, the question of basis function selection for spatial discretization of the elastic displacements is also addressed. The finite element method and an eigenfunction expansion techniques are presented and compared. All issues are examined numerically in the context of a simple beam example and the Space Shuttle Remote Manipulator System. Unlike a single-link system, the results for the latter show that all terms are required for accurate simulation of faster maneuvers. Hence, the conclusions of the paper are contrary to some of the previous findings on the validity of various models for dynamics simulation of flexible-body systems.

FREE VIBRATION OF AN ORTHOTROPIC HOLLOW BODY OF REVOLUTION

2005 ◽  
Vol 05 (02) ◽  
pp. 299-312
Author(s):  
D. REDEKOP
Keyword(s):  
Natural Frequencies ◽  
Differential Quadrature Method ◽  
Three Dimensional ◽  
Theory Of Elasticity ◽  
Constant Thickness ◽  
Body Of Revolution ◽  
Orthotropic Cylinder ◽  
Dimensional Theory ◽  
Hollow Cylinders ◽  
Definition Of

A method is developed to determine the natural frequencies of vibration of an orthotropic hollow body of revolution of constant thickness but of arbitrary smooth meridian. Equations are derived using the linear three-dimensional theory of elasticity, and a numerical solution is obtained using the differential quadrature method. The geometric generality of the solution is attained by delaying definition of local geometric parameters until the solution stage. Validation is by comparison with previously published results, including results for a hollow orthotropic cylinder. Sample results are given for orthotropic hollow cylinders and spherical segments, and conclusions are drawn.

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