Browse

You are looking at 101 - 110 of 212 items for :

Clear All
Open access

Jozef Bocko, Roland Jančo and Branislav Hučko

Abstract

The article deals with the contribution of Dr.h.c. mult. prof. Ing. František Trebuňa, CSc to the field of engineering. Born in 1947, he studied and subsequently remained at the Faculty of Mechanical Engineering, Technical University of Košice since 1965. Under his leadership 25 dissertation theses were defended in the study programs Applied mechanics, Mechatronics and Forensic engineering. He is author to 14 monographs, 16 textbooks, 5 other books, 12 university textbooks and more than 350 original scientific papers published in domestic and foreign journals and conference proceedings. Professor Trebuňa is currently the dean at the faculty and is known as a gifted educator.

Open access

Yildirim Vebil

Abstract

As a continuation of the author’s previous studies on the buckling analysis of helical springs, a closed-form formula having been obtained with the help of the artificial neural network (ANN) is proposed and discussed in detail for the first time for a cylindrical close/open-coiled helical spring with fixed ends and having a solid circular section. As far as the author knows there is no such a formula in the open-literature to consider the effects of all stress resultants (torsional and bending moments, axial and shearing forces), large helix pitch angles together with the axial and shear deformations on the buckled state. The present formula may be used in a wide range of the total number of active turns, the ratio of the free axial length to the mean helix diameter, and the spring index. It is yet again revealed that it is not appropriate to use the elementary theory to determine the critical buckling loads for open-coiled springs. The present formula may allow the deeper understanding of spring buckling mechanism and to be used directly and safely in the design processes of such closely/open-coiled springs.

Open access

Jozef Bocko, Pavol Lengvarský and Juraj Šarloši

Abstract

The buckling analysis of carbon nanotubes without and with hetero-junctions is described in this paper. The buckling behaviour was investigated by the finite element method and the carbon nanotubes were modelled as space frame structures. The results showed that the critical buckling force depends on the dimensions of carbon nanotubes. The critical buckling forces of hetero-junction carbon nanotubes are in range between critical buckling forces of carbon nanotubes of both used diameters with the same chiralities without hetero-junction.

Open access

Michael Welch

Abstract

Classical analysis methods are applied to show how flexural deflections due to shear strain in the flange pack produce bending moments and tensile loads on bolts within preloaded bolted joints. It was found that in joints made with long bolts these loads can be significant. The loads can cause yielding of the bolt, reducing bolt preload. The methods presented are adequate to demonstrate the structural integrity of joints made with long bolts or with a small footprint.

Open access

Péter Mika

Abstract

The vehicle dynamics was a very lot developed in the last twenty years. There is a huge gap in the different vehicle models in this field. Researchers need accurate the car following models because of it. There are several mathematical model, which describe the dynamics and the motion of individual vehicles. This models based on a desired velocity, which is kept by the following vehicle and even small gaps will not induce braking reactions. So this behaviour is not realistic.

Open access

Pjotrs Trifonovs-Bogdanovs and Anvar Zabirov

Abstract

Analysis and simulation of the Strapdown Inertial Navigation System (SINS) error genesis revealed that the East Feedback Contour has the greatest influence on the development of an error in this model, and angular velocity sensor Δω𝒚 is the critical element. In order to prevent the development of an error, structural correction in the East Feedback Contour, and elements that are more critical, namely in angular velocity measurement sensors is the best option.

Open access

Deniss Brodņevs

Abstract

Remotely piloted operations of lightweight Unmanned Air Vehicles (UAV) are limited by transmitter power consumption and are always restricted to Line-of-Sight (LOS) distance. The use of mobile cellular network data transfer services (e.g. 3G HSPA and LTE) as well as long-range terrestrial links (e.g. LoraWAN) makes it possible to significantly extend the operation range of the remotely piloted UAV. This paper describes the development of a long-range communication solution for the UAV telemetry system. The proposed solution is based on (but not restricted to) cellular data transfer service and is implemented on Raspberry Pi under Gentoo Linux control. The goal of the project is to develop a flexible system for implementing optimized redundant network solutions for the Non-LOS remote control of the UAV

Open access

Andris Vaivads, Jevgēnijs Tereščenko and Vladimirs Šestakovs

Abstract

The article presents a semiotic model of “aircraft conditions” in flight and multilevel structures of an aircraft. The hierarchical structure of abstract models is divided into blocks and levels that make them more compact by applying a mathematical apparatus corresponding to the goals sated. The above models were tested on the basis of statistical data on TU-154 aircraft failures for 10 years. Various aircraft functional system failures in flight were examined. The state of the aircraft is identified by normative indicators recorded in the “Aircraft Technical Operation Manual”.

Open access

František Dzianik, Štefan Gužela and Eva1 Puškášová

Abstract

The paper deals with the process properties in terms of the heat transfer, i.e. the thermal performance of the thermal-process units within a helium loop intended for the testing of the decay heat removal (DHR) from the model of the gas-cooled fast reactor (GFR). The system is characterised by a natural circulation of helium, as a coolant, and assume the steady operating conditions of the circulation. The helium loop consists of four main components: the model of the gas-cooled fast reactor, the model of the heat exchanger for the decay heat removal, hot piping branch and cold piping branch. Using the thermal calculations, the thermal performance of the heat exchanger model and the thermal performance of the gas-cooled fast reactor model are determined. The calculations have been done for several defined operating conditions which correspond to the different helium flow rates within the system.

Open access

Prasad Lalta and Khantwal Rahul

Abstract

The present investigation carried out to analyze the breaking load of single lap joint using hybrid joining techniques for alloy steel AISI 4140 and mild steel as base material by experimentally and optimized by Taguchi method and neural network. The six samples of lap joints were prepared namely: bolted joint (BJ); adhesive joint (AJ); welded joint (WJ); bolted-welded joint (BWJ); adhesive-welded joint (AWJ) and adhesivebolted joint (ABJ). The breaking load of the joints in terms of breaking load and elongation were evaluated for each joint. The effect of the adjustment attached to the joint on the breaking load and elongation were evaluated. Taguchi method was applied for given input parameters and L4 design of experiments was used. The breaking load and elongation were taken as output response. The predicted values by Taguchi method were used as target values in neural network fitting curve. Neural network fitting tool was used to check whether the obtained values were near the target value or not. Based on the achieved results, the maximum breaking load and elongation were found for bolted-welded joint.