scholarly journals Comparative Studies of the Seatings of Propulsion Plants and Auxiliary Machinery on Chocks Made of Metal and Cast of Resin Part I. Mounting on Steel Chocks

2019 ◽  
Vol 26 (4) ◽  
pp. 142-148
Author(s):  
Paweł Grudziński ◽  
Konrad Konowalski
Keyword(s):  
Comparative Analysis ◽  
Scientific Explanation ◽  
Experimental Studies ◽  
Point Of View ◽  
Bolted Joints ◽  
Engineering Practice ◽  
Bolted Joint ◽  
Science And Engineering ◽  
Analysis And Evaluation ◽  
Resin Part

Abstract This paper presents a description and the results of experimental studies of the deformation, friction and structural damping occurring in foundation bolted joints of propulsion plant components and auxiliary machinery that is rigidly mounted on sea-going ships. The rigid mounting of these devices to the ships’ structural foundations can be implemented in a traditional way, i.e. on chocks made of metal (usually of steel), or in a modern way, i.e. on chocks cast of resin, specially designed for this purpose. The main goal of this study is to perform a comparative analysis of these two solutions and to give a scientific explanation for why chocks cast of resin perform better in machinery seatings than the steel chocks traditionally used for this purpose. The paper consists of two parts. Part I presents the details of the rigid mountings of machinery to the foundations, and contains the results of experimental studies performed on a model of a foundation bolted joint with a traditional steel chock. Part II contains the results of similar studies carried out for a model of a bolted joint with a modern chock cast of resin. Next, a comparative analysis and evaluation of the results obtained for both investigated bolted joints was carried out, and conclusions were formulated to highlight important aspects of the problem from the point of view of science and engineering practice.

scholarly journals Comparative Studies of the Seatings of Propulsion Plantsand Auxiliary Machinery on Chocks Made of Metal and Cast from Resin Part II. Mounting on Cast Resin Chocks

2020 ◽  
Vol 27 (1) ◽  
pp. 126-133
Author(s):  
Paweł Grudziński ◽  
Konrad Konowalski
Keyword(s):  
Comparative Analysis ◽  
Comparative Studies ◽  
Research Work ◽  
Experimental Studies ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Structural Damping ◽  
Relevant Research ◽  
Resin Part ◽  
Plant Components

AbstractThis article is Part II of the paper containing a description and results of the experimental studies of the deformations, friction processes and structural damping that occur in the foundation bolted joints of propulsion plant components and auxiliary machinery installed on sea-going ships. Part I of this research work presents an analysis of the rigid mountings of machines and devices to the foundations on steel or resin chocks, and explains the need to carry out relevant research in this area. It also presents the description and results of experimental studies carried out for a foundation bolted joint with a conventionally used steel chock. Part II (this article) contains a description and results of similar studies carried out for a foundation bolted joint with a modern chock – cast from epoxy resin compound (EPY), specially developed for this purpose. Then, a comparative analysis of the results obtained for both bolted joints in question was made and the foundation chocks of the poured-in-place resin compound were demonstrated to better fulfill their technical tasks than the steel chocks traditionally used for this purpose.

Measurement of Bolt Clamping Forces by Electromagnetic Vibration Method Without Disassembling Bolted Joints

2006 ◽  
Author(s):  
Toshimichi Fukuoka ◽  
Nobukuni Sugano
Keyword(s):  
Contact Pressure ◽  
Experimental Studies ◽  
Service Condition ◽  
Point Of View ◽  
Bolted Joints ◽  
Joint Interface ◽  
Bolted Joint ◽  
Plate Interface ◽  
Vibration Method ◽  
Electromagnetic Vibration

The integrity and safety of a bolted joint can be greatly guaranteed by applying and maintaining an appropriate amount of bolt preloads. However, the variation of bolt preloads inevitably occurs in the service condition due to various reasons, even if the initial bolt preloads are properly applied. Accordingly, the monitoring of bolt forces in the service condition is significantly important. From the practical point of view, it is preferably conducted without disassembling the objective bolted joint. In this paper, Electromagnetic Vibration Method is introduced for monitoring the variation of bolt preloads in the service condition, and its performance is examined by experiments using bolted joints with various geometric configurations. Electromagnetic Vibration Method estimates the magnitude of bolt preload by measuring the resonant frequencies of the bolted joint, which vary in accordance with the contact pressure of the joint interface. From the experimental studies, Electromagnetic Vibration Method was found to be effective to evaluate the bolt force with a reasonable accuracy, except for the bolted joint whose plate interface being under very high contact pressure.

On the Use of Shape Memory Alloy Studs to Recover Load Loss in Bolted Joints

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Nazim Ould-Brahim ◽  
Abdel-Hakim Bouzid ◽  
Vladimir Brailovski
Keyword(s):  
Shape Memory ◽  
Analytical Model ◽  
Experimental Studies ◽  
Thermal Exposure ◽  
Element Model ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Creep Properties ◽  
Material Creep ◽  
Joint Assembly

Creep is an important factor that contributes to the clamp load loss and tightness failure of bolted joints with and without gaskets over time. Retightening of the joint can be expensive and time consuming; therefore, it is an undesirable solution. Currently, most efforts are put towards reducing load losses directly by tightening to yield, improving material creep properties, or making joint less rigid. An alternative solution of current interest is the use of bolts in shape memory alloys (SMAs). However, very few experimental studies are available, which demonstrate the feasibility of these alloys. The objective of this study is to explore the benefit of shape memory and superelasticity behavior of an SMA stud to recover load losses due to creep and thermal exposure of a gasket in a bolted-joint assembly. This paper explores several venues to investigate and model the thermomechanical behavior of a bolted joint with a nickel–titanium SMA stud. A stiffness-based analytical model which incorporates the Likhachev model of SMA is used as a representation of an experimental bolted-joint assembly. Based on this model, the rigidity of the experimental setup is optimized to make the best use of the SMA properties of the stud. This analytical model is compared with a finite element model, which also implements the Likhachev's material law. Finally, an experimental test bench with a relatively low stiffness representative of standard flanges is used, with and without gaskets to demonstrate the ability of the SMA stud to recover load losses due to gasket creep.

Heat Transfer and Friction in a Thin Air Laminar Boundary Layer over Semi-Sphere Surface

2020 ◽  
pp. 17-33
Author(s):  
V.V. Gorskiy ◽  
A.G. Loktionova
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Differential Equations ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Experimental Studies ◽  
Point Of View ◽  
Effective Length ◽  
Engineering Practice ◽  
Literary Sources

A qualitative solution to the problem of calculating convective heat transfer can be obtained only by numerically integrating the differential equations of the boundary layer, which is associated with overcoming a number of computational problems. Consequently, it is important to develop relatively simple, but fairly high-precision calculation methods. As a first approximation to solving this problem, we can consider the use of the effective length method. From the practical point of view, this method is characterized by satisfactory accuracy of calculating convective heat transfer, which has led to its widespread use in aeronautical design engineering. However, this method is also characterized by a relatively high complexity, although it is much lower than that in numerical integration of the differential equations of the boundary layer. The most effective approach to solving heat transfer and friction problems in engineering practice is to use simple algebraic formulae obtained on the basis of approximating the results of rigorous numerical calculations, or experimental studies. Unfortunately, there is no information in literary sources about the accuracy of these formulae under various conditions of product functioning. This problem is solved on the basis of a systematic numerical calculation of the equations of the boundary layer in the most rigorous theoretical calculation, as well as a detailed analysis of the accuracy of the obtained algebraic formulae and their literary analogues

VAT Refund under Conditions of Zero Tax Rate

2007 ◽  
pp. 120-136
Author(s):  
R. Saakyan ◽  
I. Trunin
Keyword(s):  
Comparative Analysis ◽  
Point Of View ◽  
Tax Administration ◽  
Tax Rate ◽  
Export Sector ◽  
Tax Legislation

Main directions of tax legislation development are considered in the article from the point of view of relevancy of zero tax rate implementation and tax refund. Special emphasis is placed on the problem of tax refund delay that undermines the competitiveness of the export sector of economy. Comparative analysis of VAT refund mechanisms in different countries and Russia with respect to effectiveness of tax administration has allowed to formulate some hypotheses concerning relevant parameters of refund and test them with the help of various methods and models.

Timber Auctions in the Context of the Modern Auction Theory

2007 ◽  
pp. 86-94
Author(s):  
A. Manakov
Keyword(s):  
Theoretical Analysis ◽  
Auction Theory ◽  
Point Of View ◽  
Theoretical Point ◽  
English Auction ◽  
Analysis And Evaluation

The article provides theoretical analysis and evaluation of the timber auctions reforms in Russia. The author shows that the mechanism of the "combined auctions", which functioned until recently, is more appropriate from the theoretical point of view (and from the point of view of the Russian practice) as compared to the officially approved format of the English auction.

The role of graining in ensuring food security

2020 ◽  
pp. 75-79
Author(s):  
R. M. Gambarova
Keyword(s):  
Food Security ◽  
Comparative Analysis ◽  
Systems Approach ◽  
Point Of View ◽  
Government Support ◽  
Grain Production ◽  
The Government ◽  
Favorable Conditions ◽  
Grain Farms

Relevance. Grain is the key to strategic products to ensure food security. From this point of view, the creation of large grain farms is a matter for the country's selfsufficiency and it leading to a decrease in financial expense for import. Creation of such farms creates an abundance of productivity from the area and leads to obtaining increased reproductive seeds. The main policy of the government is to minimize dependency from import, create abundance of food and create favorable conditions for export potential.The purpose of the study: the development of grain production in order to ensure food security of the country and strengthen government support for this industry.Methods: comparative analysis, systems approach.Results. As shown in the research, if we pay attention to the activities of private entrepreneurship in the country, we can see result of the implementation of agrarian reforms after which various types of farms have been created in republic.The role of privateentrepreneurshipinthedevelopmentofproduction is great. Тhe article outlines the sowing area, production, productivity, import, export of grain and the level of selfsufficiency in this country from 2015 till 2017.

Masonry: the brittle or plastic material?

2019 ◽  
pp. 22-28
Keyword(s):  
Plastic Material ◽  
Experimental Studies ◽  
Point Of View ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
Base Materials ◽  
Stress States ◽  
Creep Deformations ◽  
Structural Point

The results of experimental studies of masonry on the action of dynamic and static (short-term and long-term) loads are presented. The possibility of plastic deformations in the masonry is analyzed for different types of force effects. The falsity of the proposed approach to the estimation of the coefficient of plasticity of masonry, taking into account the ratio of elastic and total deformations of the masonry is noted. The study of the works of Soviet scientists revealed that the masonry under the action of seismic loads refers to brittle materials in the complete absence of plastic properties in it in the process of instantaneous application of forces. For the cases of uniaxial and plane stress states of the masonry, data on the coefficient of plasticity obtained from the experiment are presented. On the basis of experimental studies the influence of the strength of the so-called base materials (brick, mortar) on the bearing capacity of the masonry, regardless of the nature of the application of forces and the type of its stress state, is noted. The analysis of works of prof. S. V. Polyakov makes it possible to draw a conclusion that at the long application of the load, characteristic for the masonry are not plastic deformations, but creep deformations. It is shown that the proposals of some authors on the need to reduce the level of adhesion of the mortar to the brick for the masonry erected in earthquake-prone regions in order to improve its plastic properties are erroneous both from the structural point of view and from the point of view of ensuring the seismic resistance of structures. It is noted that the proposal to assess the plasticity of the masonry of ceramic brick walls and large-format ceramic stone with a voidness of more than 20% is incorrect, and does not meet the work of the masonry of hollow material. On the basis of the analysis of a large number of research works it is concluded about the fragile work of masonry.

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

TRANSLATION OF SOCIAL AND POLITICAL TERMINOLOGY OF CHINESE LANGUAGE AS A PROCESS OF NORMATIVE PRACTICE IN CONTEXT MODELS

2020 ◽  
Vol 6 (3) ◽  
pp. 172-182
Author(s):  
Saodat Nosirova ◽  
Keyword(s):  
Comparative Analysis ◽  
Law Enforcement ◽  
Chinese Language ◽  
Integrated Approach ◽  
Point Of View ◽  
Modern Chinese ◽  
Normative Practice ◽  
Context Models

The article is devoted to a comparative analysis of the socio -political terminology of the modern Chinese language.The purpose of the article is to search for an integrated approach to the study of the cognitive side of social and political terms of the Chinese language from the point of view of law enforcement in the process of translating official materials from Chinese into Uzbek and / or Russian and vice versa

Sign in / Sign up

Export Citation Format

Share Document