Browsing by Subject "FEM"

Now showing 1 - 20 of 26

Access status: Open Access ,
Analiza cieplno-wytrzymałościowa połączenia walczaka i rury opadowej w warunkach nieustalonych
(Wydawnictwa AGH, 2006) Taler, Jan; Michalczyk, Krzysztof
In this paper the method based on German standard TRD of calculating acceptable speed of heating and cooling power boilers was presented. It was indicated that stresses occurring during heating and cooling according to this standard are much smaller than the acceptable ones. It motivates shortening of starting and shutting-down times and searching for new methods defining acceptable speeds of heating and cooling power boilers.
Access status: Open Access ,
Analiza przyczyn powstawania pęknięć zmęczeniowych w konstrukcji bębna pędnego maszyny wyciągowej
(Wydawnictwa AGH, 2005) Cichociński, Andrzej; Ładecki, Bogusław
Still in use today there are some hoisting mining machines with motion wheels, the construction of which uses ri-gid 'U' shaped diaphragms to connect side disks. In such wheels periodically, after servicing, fatigue cracks are being found. The authors performed strength analysis done by the finite elements method, and verified its results using appropriate tensammetric measurements. The measurements and analyses performed confirmed that direct cause of the fatigue cracks in the barrels is over-rigidity of the structure due to stiff diaphragms joining the wheel disks. Based on this, recommendations were issued regarding modernization of motion wheels in the discussed ho-isting machines.
Access status: Open Access ,
Application of a measuring and recording system with MEMS technology for a powered roof support
(Wydawnictwa AGH, 2024) Trzop, Konrad
Innovative technologies in hard coal production are indispensable for building a modern business enterprise. The pace of environmental and social changes inspires the need for continuous improvement of the coal mining process. The domain of machinery and equipment is the most important element of the entire production process. Machines and equipment require the constant monitoring of their operating parameters to ensure production continuity and safety. A solution addressing those needs is a measuring system that records the parameters of the powered roof support. The constructed measuring system uses MEMS technologies to measure changes in the transverse and longitudinal inclination of the elements and the height of the powered roof support. The measuring system allows for determining the parameters of the powered roof support's operation in the mining wall. The following paper presents an example of the use of MEMS technology in the measuring system sensors, as well as the stages of real-life research on adapting the powered roof support to the measuring system.
Access status: Open Access ,
Assessment of integrity of operating gas pipelines
(Wydawnictwa AGH, 2018) Ładecki, Bogusław; Matachowski, Filip; Bednarz, Stanisław
Gas pipelines that have been in operation for many years require supervision, taking into account the places and conditions of their usage. The currently applicable normative regulations do not fully determine the scope of the integrity control of such gas pipelines. The standards provide general guidelines for monitoring corrosion phenomena in pipelines, allowing the use of simplified strength patterns based on a flat state of stress, in actuality, real objects usually have complex three-dimensional structures. Such an approach may be a reason for committing significant errors in determining the state of stresses and strains in the construction of pipelines, which is a significant problem in assessing the integrity of pipelines (when combined with the lack of a formulation of the appropriate admission criteria). This paper presents a methodology for assessing the integrity of pipeline structures operating at ambient temperatures based on conducting comprehensive measurements of wall thickness defects (in connection with performing necessary defectoscopy tests). The results of these measurements and non-destructive tests are the basis for the analysis of stress strength and MES deformation based on the verified real geometry as well as the method of supporting the pipelines. The information obtained on this basis regarding the pipeline structure areas of the highest efforts is the basis for selecting the critical areas of pipeline construction for which they should be repaired or modernized, or a monitoring program should be developed using non-destructive tests.
Access status: Open Access ,
Bucket wheel excavator cutting tooth stress and deformation analysis during operation using Finite Elements Method (FEM)
(Wydawnictwa AGH, 2018) Kertész Brînaş, Ildiko; Rebedea, Narcis Ionel; Oltean, Ilie Luciano
In the case of bucket wheel excavators, the cutting process is influenced by the forces opposing the working elements and cutting tools. These forces determine the choice of machines and their parameters as well as the operating method [1, 2]. Studies conducted on the failure causes of mechanical parts show that the cutting and loading systems cause the highest rate of failure - about 32% of all recorded mechanical failures [3]. In this paper, we will use the Finite Element Method (FEM) to analyze the deformations and stresses acting on the cutting teeth mounted on the rotor of BWEs. For this, Solid-Works® software was used, both as a CAD tool to design the teeth as well as to model and simulate the phenomena.
Access status: Open Access ,
Comparison of passive and active methods for sound radiation reduction from the clamped plate
(2010) Kozupa, Michał; Wiciak, Jerzy
The paper is an analytical and experimental study of smart structure, which consist of steel plate with bonded PZTs and porous elastomer layer. Active control of sound radiation from a clamped at the edge square plate is examined. Simulations and numerical computation of the experiment are performed in ANSYS environment. Calculations of plate vibration and sound radiation under stepped harmonic force are performed. The experimental set-up is placed in coupled reverberation chambers and the test plate is placed in the hole. A variety o test cases were studied for three different plates: steel plate + PZT, steel plate + elastomer layer, steel plate + PZT + elastomer layer. The aim of the paper is to illustrate the possibilities of using piezoelectric materials as an active control and elastomer layers as passive methods in one structure to improve the transmission loss.
Access status: Restricted ,
Design of an automated device for canvas frame assembly
(Data obrony: 2020-10-14) Herzyk, Michał
Wydział Inżynierii Mechanicznej i Robotyki
Access status: Open Access ,
Designing folding wall box pallets
(2014) Wolny, Stanisław; Ładecki, Bogusław; Matachowski, Filip
Designing of modern box pallets with folding walls, which are used for example to transport tires, requires fulfilment of a number of performance requirements. Such pallets, adapted to be moved by forklifts, are stored or transported without loading with walls folded, and during operation they are put together in the piles of a few pieces and braced by the transport belts. Difficult operating conditions are related to necessity to provide resistance of construction of a pallet or their pile on: bending, piling, stability, hitting in case of a free-fall, lifting by forklift, as well as the resistance to horizontal strokes by both edges and legs. In order to meet the above mentioned requirements, it is necessary to implement the relevant tensile FEM analyses, which are then reviewed by the relevant experimental testing. The paper discuss the requirements specified by standards for designing of the above mentioned pallets and presents FEM results in the process of pallets' designing.
Access status: Open Access ,
Effects of strain rate on work hardening of HSLA and Ti-IF steels
(2006) Stefańska-Kądziela, Monika; Majta, Janusz; Muszka, Krzysztof
This study presents some aspects of modeling of the mechanical behavior and strengthening mechanisms of HSLA and Ti-IF steels deformed under high strain rate conditions. Axisymmetrical compression tests at a wide range of strain rates have been performed to determine the mechanical and microstructural response of the material. The experimental data were compared with the results of computer modeling where proposed constitutive models are implemented in FEM code. The test data are used to find suitable values related to Zerilli-Armstrong model for microalloyed steels.
Access status: Open Access ,
Endurance analysis of Koepe pulleys with peripheral ribs
(2012) Wolny, Stanisław; Ładecki, Bogusław
There are numerous hoisting installations operated in Polish mines that are equipped with winding gear incorporating a Koepe pulley reinforced with peripheral ribs, where the symptoms of fatigue cracking are often revealed. Current repairs of those areas help mitigate for this undesirable phenomenon for a short time only. In order to eliminate this problem, steps have been taken to identify the origins and propagation patterns of fatigue cracks in Koepe pulleys. A numerical model of a Koepe pulley is developed and the endurance analysis is performed by the FEM method, preceded by a dynamic analysis of the normal duty cycle of the hoisting installation. The results of dynamic and endurance analyses are verified through experimental testing on a real object, involving force and stress measurements taken at selected points on the Koepe pulley. Those measurement data provide the background for the fatigue endurance assessment and new redesigns of the Koepe pulley structure.
Access status: Open Access ,
Evaluation of the state of stress in structural components of a screen separator
(2010) Wolny, Stanisław; Banaszewski, Tadeusz; Dzik, Stanisław; Matachowski, Filip
This study summarises the results of FEM analysis of the state of stress generated in structural components of a PZ3R screen separator under the typical operating conditions. Simplifications underlying the numerical analysis were verified by measuring the stresses in selected parts of the machine. Resistance test data indicated the directions for further modifications of structural elements of the screen separator, at the same time confirming the adequacy of these tests and emphasising the importance of the sequence of the applied tests.
Access status: Restricted ,
Modelowanie krótkotrzpieniowej endoprotezy stawu biodrowego
(Data obrony: 2017-01-23) Harasimowicz, Barbara
Wydział Elektrotechniki, Automatyki, Informatyki i Inżynierii Biomedycznej
Access status: Open Access ,
Modelowanie numeryczne wpływu górniczych deformacji podłoża na grupę budynków w zwartej zabudowie miejskiej
(Wydawnictwa AGH, 2009) Florkowska, Lucyna
The prediction of the influence of subsoil deformations on the condition of a building system is of great importance as, among other things, it helps prevent mining damages. Results of the numerical modelling influence of the underground mining on the buildings in the high-density housing were introduced at work. Recognizing the possibility of calculating stress and strain state on the base of standard geodetic measurements and numerical simulation was the purpose of this the work. Although the applied numerical model was simplest model, results of experiment showed themselves very much interesting.
Access status: Open Access ,
Naprężenia, odkształcenia i konwergencje na różnych głębokościach kopalń soli, studium modelowe dla chodnika w górotworze solnym
(Wydawnictwa AGH, 2009) Maj, Agnieszka
The paper presents the influence of depth on stresses and strains around the gallery in salt rock mass. The method of taking the values of initial stresses corresponding to the state of stress in salt rock mass for analyses is described. The distributions of stress, strain and convergence of gallery are calculated for elastic-viscous medium using Finite Element Method. The results of this paper may be used for recognition of the stress conditions in salt rock mass and estimation of viscous properties of rock mass on the basis of the convergence measurements at various depths.
Access status: Open Access ,
Problems with rectification of hoist supports on the example of a semi-portal bridge-crane with a lattice structure
(2014) Ładecki, Bogusław; Matachowski, Filip
The long period and conditions of operation are the cause of various types of severe damage to cranes used in the steelworks industry. Among the more dangerous and difficult to eliminate crane damage types, there is excess durable deflection of its supports from vertical axis. The object of the study is the semi-portal grab bridge-crane with steel lattice structure, for which deflection of a fixed support was detected that several times exceeded permissible values. For this crane, rectification was performed aimed at bringing fixed supports to the vertical line by stabilisation of the corrected location of the bearing structure of the crane using additional angle braces. The analysis of periodical geodetic measurements of the crane structure showed insufficient effect of the rectification, whereas loss of stability of some rods in the fixed support was detected. The study involved the FEM strength analysis of the crane, which revealed that the applied rectification method caused redistribution of forces in the rods of the fixed support, resulting in the loss of stability of some rods of the support, thus questioning the effectiveness of the rectification method applied.
Access status: Open Access ,
Procedure of building and analysis of the information database of the resistance of existing bridge structures to mining tremors
(Wydawnictwa AGH, 2017) Rusek, Janusz
Mining tremors are one of the manifestations of negative impacts of the mining industry on the environment. In order to protect building structures against the damaging effects of ground vibrations, it is required that their dynamic resistance be determined. This problem is of particular importance for the existing bridge structures that were not designed for the potential occurrence of mining tremors. This paper presents the assumptions of and a method for acquiring data on the dynamic resistance of existing bridge structures located in mining areas as a result of numerical calculations using the Finite Element Method (FEM). Object resistance was described by the limit values of the acceleration of ground vibrations in the vertical and horizontal planes that can be carried by the existing structure without compromising safety. Taking into account the geometrical and material diversity, 3,000 numerical models of reinforced concrete overpasses were created. Then, for each object, numerical calculations using the FEM were performed, which resulted in the determination of permissible values of the acceleration of ground vibrations defi ning their dynamic resistance. The created database was subjected to a preliminary analysis in order to detect linear relationships binding the data that describe the geometry and material properties of individual structures with their dynamic resistance to the impact of mining tremors. As a result of these studies, variables were selected that formed the basis for creating a multiple linear regression model (MLR). Analysis of the obtained results allowed us to assess the possibilities of using linear models to determine the dynamic resistance of bridge structures subjected to mining tremors.
Access status: Restricted ,
Prognozowanie osiadań powierzchni terenu w warunkach zróżnicowanej wilgotności objętościowej
(Data obrony: 2017-10-25) Lazar, Damian
Wydział Geologii, Geofizyki i Ochrony Środowiska
Prognoza osiadań powierzchni terenu w warunkach zróżnicowanej wilgotności została wykonana za pomocą modelowania komputerowego. Posłużono się programami pakietu Geo-Slope, które bazują na metodzie elementów skończonych. Danymi wyjściowymi do stworzenia modeli był plan sytuacyjny oraz dane z wierceń, przeprowadzonych na zboczu Wzgórza Św. Bronisławy, przy ul. Fabijańskich w Krakowie. Do symulacji wykorzystano programy SEEP/W oraz SIGMA/W. W pierwszym stworzono schematy obliczeniowe o zróżnicowanych warunkach wilgotnościowych. W drugim natomiast stworzono modele osiadań powierzchni terenu. W końcowym etapie zestawiono ze sobą modele wynikowe oraz porównano parametry wilgotnościowe oraz wielkości przemieszczeń.
Access status: Open Access ,
Shape prediction during the free forming process of semi-finished products electrodynamically worked
(Wydawnictwa AGH, 2007) Kot, Andrzej; Bednarczyk, Józef
Possibility of free forming for semi-finished products and giving them demanded shapes without presence of forming dies distinguish the electrodynamic method in relation to standard technologies of metal plastic working, because there are no difficulties of using punch - die instrumentations. The article presents considerations referred to prediction possibilities of final shape of pipe and flat semi-finished products electrodynamically formed without using forming dies.
Access status: Open Access ,
Strength analysis of a gantry crane of a coating structure
(2012) Ładecki, Bogusław; Badura, Sławomir; Matachowski, Filip
Gantry cranes with coating construction are used in Polish steel industry much less than truss bridges. For several bridges, which span and the supports have coating construction, there were made series of non-destructive testing, which revealed the presence of numerous fatigue cracks: in the area of a beam pad, the coating, as well as other elements of their supporting structure. Periodically carried out repairs and strengthening of bridges have not eliminated the problem of the emergence of more fatigue cracks. The analysis of FEM, verified by extensometer measurements of strains, gave the basis to designate the most strenuous areas of the construction. Gathered results of periodic non-destructive testing, combined with obtained results of FEM analysis, were the basis for designing appropriate reinforcements and indication the scope of conducting non-destructive testing of considered construction of bridges with coating.
Access status: Open Access ,
Stress analysis in helical springs with closed end coils machined from cylindrical sleeves
(Wydawnictwa AGH, 2006) Salawiński, Józef; Michalczyk, Krzysztof
The review of stress calculation methods in helical springs with rectangular cross-section wire is introduced in this paper. It is demonstrated that methods described in literaturę have various accuracy. Also, the modern construction of helical spring machined from tubular blanks is presented. It is indicated, using Finited Elements Me-thod, that existing for classical springs with opened ends stress calculating methods, are not suitable for springs with capped ends, because the stresses calculated from them are much smaller than the real ones.