Optimization of thin-walled constructions in CAE system ANSYS

Znanstveni pristup rješavanju problema optimiranja sa stanovišta naprezanja i deformacije u konstrukciji provedeno je u ovom radu na primjeru teleskopske ruke. To je uglavnom zbog činjenice da, unatoč širokom spektru uporabe teleskopskih ruku, ne postoje općenito valjana, znanstveno dokazana i prezentirana teorijska načela za njihovo projektiranje. Sa stajališta mehanike, krak teleskopske ruke, kao predmet istraživanja može se svrstati u tankostjene konstrukcije. U stvari, riječ je o zatvorenom tankostjenom presjeku opterećenom kombinacijom savojnih i torzijskih momenata. Primjenjujući metodu konačnih elemenata (MKE) povezanu s CAE sustavom ANSYS moguće je projektirati optimalan oblik poprečnog presjeka poluge teleskopske ruke. Uspoređujući izračunate vrijednosti naprezanja i deformacije s vrijednostima dobivenim eksperimentalnim mjerenjima, moguće je procijeniti učinkovitost procesa optimiranja.Solving optimization problems from the standpoint of structural stresses and strains can be carried out scientifically on the example of telescopic jib. It is mainly due to the fact that despite a broad spectrum of the telescopic jib utilization there are no generally valid, scientifically proven and presented theoretical principles for their designing. From the viewpoint of the classification of mechanics, the arm of telescopic jib as a subject of study can be ranked among thin-walled constructions. In fact, it is a case of enclosed thin-walled bars stressed in operation by a combination of bending and torsion moments. Applying the Finite Element Method (FEM) in connection with the CAE system ANSYS, it is possible to design an optimum shape of the cross-section of the telescopic jib arm. Comparing the calculated values of stresses and deformations with the values obtained by experimental measuring, it is possible to evaluate the effectiveness of the optimization process

An approximation of deflection line function at the rod loaded by buckling under self-weight

Rad se bavi aproksimacijom točne funkcije linije otklona za štap opterećen izvijanjem zbog vlastite težine pomoću funkcije, što je najbolje prikazano točnim oblikom ovog štapa. U ovom radu predlažemo metode derivacije kritične duljine izvijanja pomoću točnog rješenja i pomoću metode energije. Za zamjenske funkcije linije otklona su izabrane varijante goniometrijskih funkcija i polinomi. Pojedinačni koeficijenti funkcija su izabrani na temelju postojećih rubnih uvjeta i u slučaju nedovoljnog broja, oni su izabrani kako bi se izrazio točan oblik linije otklona štapa na najprikladniji način, koji je prenesen iz konkretnog primjera rješenja pomoću softvera SolidWorks. Rad prikazuje pogreške kritičnog izračuna duljine izvijanja nasuprot točnom rješenju, kao i maksimalna apsolutna i relativna odstupanja kod bočnog pomicanja za odabranu funkciju. Od pojedinačnih zamjenskih funkcija je naknadno izabrana ona koja ispunjava uvjet za opće korištenje i ima najmanja odstupanja od točnog rješenja.The paper deals with an approximation of the exact deflection line function at a rod loaded by self-weight buckling via the function, which is best-presented by the exact shape of this rod. In this paper, we suggest the methods of derivation of the critical buckling length by the exact solution and by the energy method. For the substitute functions of deflection line, the variants of goniometric functions and polynomials are chosen. Individual coefficients of the functions are chosen on the basis of existing boundary conditions and in the case of their insufficient count, they are chosen in order to express the exact rod deflection line shape in the most suitable way, which was transposed from the concrete example solution by SolidWorks Simulation software. The paper shows the errors of critical buckling length calculation against the exact solution, as well as the maximum absolute and relative deviations in the lateral displacement for the chosen function. From the individual substitute functions, one function that meets the condition for general use and has the lowest deviations from the exact solution, is subsequently chosen

Alternative evaluation of the properties of the silica sands

For the evaluation of silica sands, which belongs to the most employed sands of foundry molding mixtures, there are a number of methods and techniques to characterize their quality. This implies good knowledge of their strengths and weaknesses. However, a small proportion of published results are dedicated to the impact of transport on transport routes in the foundry and the processes of dry reclamation on the properties of the silica sands, in particular on changes to the granulometry and the formation of undesirable dust sands shares, which significantly affect the properties of the sand mixture. The aim of this contribution is the evaluation of inclination of the silica sand to crush (the formation of dust, change the granulometry) according to the newly developed methodology with regard to its nature of sand (genesis, the shape of the grains, the character of the surface).Piaski kwarcowe stanowią podstawowe tworzywo na osnowę mas formierskich i rdzeniowych. Stąd istnieje bardzo wiele metod charakteryzujących ich jakość, co umożliwia poznanie ich zalet i wad. Mało jest jednak prac opisujących wpływ systemów transportowych odlewni oraz systemów suchej regeneracji mas na zmianę ich składu granulometrycznego oraz zawartości frakcji pylastych na właściwości mas. Celem niniejszej pracy jest ocena skłonności piasku kwarcowego do rozkruszania, (tworzenia frakcji pyłowych i zmianie granulometrii) według nowo opracowanej metodyki uwzględniającej charakterystyczne cechy piasku wynikające z jego pochodzenia, kształty ziaren i charakteru powierzchni.Web of Science59273873

Determination of Critical Load in a Nonuniform Circular Steel Column under the Eccentric Axial Load

The purpose of this paper is to determine a critical load for a nonuniform circular steel tube under eccentrically axial load. The circular tube has variable cross section at flattened ends with existing holes used for connection between members. Three different cases of eccentricities are studied with the drilled holes either on the same side or on the opposite side of column axis. The critical load is calculated from the differential equation of deflection curve which is solved by the power series and Runge-Kutta method. In addition, the loading tests were performed on a total of 180 specimens with different diameters, slenderness, and connection. The calculated results are compared and shown in a good agreement with those obtained from the experimental results. The results also show that the critical load decreases rapidly even at a small value of eccentricity and thus may have a significant effect on the load-carrying capacity

Optimization of the cloud for setup of hardware of remote laboratories

Few years ago, we built our own virtualized cloud for REMLABNET and we still are taking benefits of this decision. This item handles with using Cloud computing platform for providing Remote laboratories. This work shows, how it is possible to save money if we use centralized system for more consumers. Every consumer can use access to centralized portal in the Cloud computing from Consortium REMLABNET. Every item is focused on environments of universities, where this cloud is existing and this is what we want to use for remote labs. This is item from practice knowledge and experiences about system function and managing virtual platform and next constuction and optimization this proposal. © 2020. All rights reserved.Trnava in Trnava [22/TU/2020

Innovation of the production process of coin dies to increase their service life

The article deals with the problem related to the service life of the coin dies. The faultless condition of tools during the long-time process of the production of the coins is a basement for their quality. It is influenced by several aspects. The most important factors can be considered the material of the coin die - especially its purity, relief production technology, heat treatment - especially the correct observance to procedures and the choice of equipment, achieved mechanical properties, method of final relief treatment - e.g., coating and the existence of residual stresses in the tool. The aim of the present research was to examine the cause of the failure and damage of the coin dies after production of a small number of coins and, accordingly, to make changes in the production process to prolong their service life. By monitoring the individual steps of the production process, it was possible to identify specific causes of premature decommissioning of coin dies. Innovations have been made at each step of the production process to extend the life of the coin. The paper presents the modifications in the heat treatment of the coin dies as one of the basic improvements in their no-failure long time operation. This, together with other identified shortcomings in the tool manufacturing process, has contributed to an increase in the number of coins minted from around 6,000 to 740,000 coins. © 2023 The Authors. Published by Elsevier B.V.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (APVV-19-0550); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (005TUKE-4/2021

Road to strengthen of virtual infrastructure and security of remote laboratories on Trnava University in Trnava

Many organizations, both large and small, are investigating the potential of storage architectures for their companies. Few years ago, we built our own virtualized cloud for REMLABNET and we still are taking benefits of this decision. This item handles with using Cloud computing platform for providing Remote laboratories. This work shows, how it is possible to save money if we use centralized system for more consumers. Every consumer can use access to centralized portal in the Cloud computing from Consortium REMLABNET. Every item is focused on environments of universities, where this cloud is existing and this is what we want to use for remote labs. This is item from practice knowledge and experiences about system function and managing virtual platform and next construction this proposal.Trnava in Trnava [22/TU/2020

The friction factor dependence on the load and revolutions in sliding bearings without relubrication

Ovaj članak se bavi eksperimentalnim istraživanjem faktora trenja kod kliznih ležaja bez ponovnog podmazivanja. Istraživanje uključuje određivanje iznosa faktora trenja i usporedbu ovisno o opterećenju i broju okretaja mjerenih na kliznom paru bez ponovnog podmazivanja koji se sastoji od kliznih ležaja i vratila. Rezultat ovog pokusa je pokazatelj izmjerenih vrijednosti kliznog para u radnim uvjetima. Sve slike mjerenja i uvjeta opterećenja za svaki ležaj predstavljene su pomoću dijagrama.This article is focused on experimental research of the friction factor in sliding bearings without relubrication. The research includes study of friction factor values and their comparison depending on load and revolutions measured on sliding pairs, consisting of a sliding bearing and a shaft, without relubrication. The result of this experiment is an evidence of values measured reflecting the sliding pair actions under operation conditions. All the represented measured results and load conditions of each bearing are presented via graphs

REMLABNET IV - LTI federated remote laboratory management system with embedded multiparameter simulations

The recent progress in REMLABNET (www.remlabnet.eu ), namely its LTI Federation possibilities with other systems and multiparameter simulations embedded, is presented together with the main recent features of REMLABNET (as a Remote Laboratory Management System). At present the available real remote experiments have been provided for Go-Lab EU FP 7 project. The system with about 20 remote experiments has been with success running since 2013 and has been since constantly improved thanks to the project of the Swiss National Science Foundation (SNSF) - "SCOPES".Swiss National Science Foundation (SNSF) - "SCOPES" [IZ74Z0_160454]; Internal Agency Grant of the Tomas Bata University [IGA/FAI/2016

K problematike výrazovej hodnoty ľudského pohybu

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