Wyniki wyszukiwania - BazTech

1

The influence of the hydropneumaticaccumulator on the dynamic and noise of the hydrostatic drive operation

Stosiak Michał, Karpenko Mykola

Eksploatacja i Niezawodność

|

2024

|

Vol. 26, no. 2

art. no. 186169

EN

The article presents the possibility of influencing the hydrostatic drive's dynamics and noise using a hydropneumatics accumulator. The possibility of limiting the maximum dynamic load during the start-up period of a drive equipped with an accumulator and controlled by a slide distributor is presented in the article. The influence of the accumulator on the sound pressure level and its relationship with the maximum dynamic values of the working fluid pressure in the hydraulic system is also described. Experimental studies of the dynamics and acoustics of laboratory hydrostatic systems were performed. A dynamic model of a hydrostatic drive equipped with an accumulator was developed, which was used to perform simulation tests illustrating the impact of the accumulator capacity on the system's dynamics. Acoustic tests were carried out for a system with a linear hydrostatic drive simulator.

2

Water Supply Networks - performance modelling and assessment

Pietrucha-Urbanik Katarzyna, Tchórzewska-Cieślak Barbara, Eid Mohamed

Safety and Reliability of Systems and Processes

|

2023

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Summer Safety and Reliability Seminar 2023

175--186

EN

Performance modelling and assessment of Water Supply System (WSS) is a critical activity in system management process. It contributes into producing indicators necessary for the optimisation of the system operation, maintenance, safety, and resources use. The Water Supply Network (WSN) is a major component of any WSS. Assessing the performance of the WSN requires the development of dynamic-probabilistic models and the use of performance notions that are beyond the local availability and reliability of a cluster of pipes (mains, connections, and distributions) or nodes. The proposed performance notions are fully described in terms of performance-levels. The proposed modelling scheme is applied on a real WSN that has slightly been modified to preserve the didactic quality of the chapter and render the modelling scheme accessible at its first uses. Once the use of the scheme is mastered, its exploitation for real and complex WSN is straight forward.

3

Comparison of the effects of anthropogenic seismic events and natural earthquakes on buried infrastructure network components

Rusek Janusz, Słowik Leszek, Tajduś Krzysztof

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2023

|

Vol. 71, nr 6

art. no. e147347

EN

Mining tremors may have an impact on the safety risk of steel pipelines through their effects. It is therefore important to quantify the impact of a high-energy mining tremor in terms of strength. In addition, a comparison of the results obtained with the effect of a seismic tremor can illustrate the scale of such a hazard. Recently, this has been a very frequently raised issue in the area of surface protection against negative mining impacts and the protection of post-mining areas. Ensuring safe use is particularly important for gas transmission elements. This paper presents the results of a comparative analysis of the impact of mining tremors and seismic impacts on a specimen steel pipeline segment. The analyzed pipeline is located in the eastern part of Poland in the area of paraseismic impacts of the LGCD (Legnica-Glogow Copper District) mine. For this purpose, an analytical approach was used to assess the impact of seismic wave propagation on underground linear infrastructure facilities. Accelerogram records for the 02-06-2023 seismic tremor from Turkey and the mining tremor for 11-25-2020 were used. In the case of the design of underground pipelines, the cross-section of the element for which measures describing wall stress and the ovalization of the cross-section are determined is usually considered. In the situation of the influence of seismic wave propagation or so-called permanent ground deformation, the response of the pipeline in the longitudinal direction is analyzed. As a final result, longitudinal strains transferred to the pipeline as a consequence of the propagating seismic wave and mining tremor were determined. The absolute difference between the deformations in the ground and along the length of the pipeline was determined. This type of analysis has not been carried out before and provides new insights into the topic of paraseismic impacts on the scale of their interaction with natural earthquakes. Mining tremor data was obtained from the mine’s seismological department. The seismic tremor data, on the other hand, was downloaded via the publicly available ESM (Engineering Strong- Motion Database).

4

A Comprehensive Review of the Quadratic High Gain DC-DC Converter for Fuel Cell Application

Jayachandran Divya Navamani, Sathik Jagabar, Padhi Tanmay, Kumari Aditi

International Journal of Electronics and Telecommunications

|

2022

|

Vol. 68, No. 2

299--306

EN

In the recent times, lot of research work carried out in the field of fuel cells explicitly divulges that it has the potential to be an ultimate power source in upcoming years. The fuel cell has more storing capacity, which enables to use in heavy power applications. In these applications, power conditioning is more vital to regulate the output voltage. Hence, we need a dc-dc converter to provide a constant regulated output voltage for such high-power system. Currently, many new converters were designed and implemented as per the requirement. This paper has made comparative study on several topologies of the quadratic high gain dc-dc converter and the applications where these topologies can be used when the fuel cell is given as a source. Also, we have compared various parameters of all the converters considered and generated the results with steady-state and dynamic study. In this article, we briefed the types of analysis carried on the dc-dc converter to study its performance. Moreover, various application of fuel cell is presented and discussed. This paper will be a handbook to the researchers who start to work on high gain dc-dc converter topologies with quadratic boost converter as a base. This article will also guide the engineers to concentrate on the fuel cell components where it needs to be explored for optimizing its operation.

5

Dynamic fuzzy model for detecting verbal violence in real time

Campos Obed, Pancardo Pablo, Hernandez-Nolasco Jose Adan

Computer Science

|

2022

|

T. 23 (4)

467--493

EN

The crime rates in Mexico have been increasing in recent years; every day, there are reports on social media and in the news where assaults and verbal aggression by criminals can be seen. Public transportation units suffer from violence that authorities have not been able to reduce despite their efforts. This is why we have developed a fuzzy logic model that can adapt to almost any scenario thanks to the dynamism that we have implemented in each of its stages. We have obtained promising results that we believe will be of great help to the authorities for detecting the exact moment in which verbal aggression that is typical of a violent assault is happening in real time. This is a tool to help the authorities, not a substitution; we are simply making use of the latest technologies that are available to us. The goal of this paper is to provide a novel method for Mexican authorities in Mexico City in order to help the actual surveillance systems make faster decisions about whether violent assaults are happening or not.

6

Network connectivity dynamic modelling

Eid Mohamed

Safety and Reliability of Systems and Processes

|

2021

|

Summer Safety and Reliability Seminar 2021

117--127

EN

The chapter presents an approach based on basic notions issued from the graph theory and from the system reliability theory. The approach seeks to describe the transitions in the connectivity state of non-directional graphs induced by systemic losses of nodes and edges. Each component loss (node or edge) represents a transition and results in a connectivity degradation. Some of the transitions are classified as non-critical while others are critical. Degradations are measured using the notion of topological graph diameter issued from the graph theory. The critical transition notion is issued from the system reliability theory. The approach determines the degraded graph diameter corresponding to each possible transition and subsequently the criticality of the transition. The criticality threshold is determined by the highest acceptable connectivity order which is a function of the degraded graph diameter. A network with 9 nodes and 15 edges is used as an academic study case to illustrate the applicability of the approach. Nodes are supposed to be identical, as well as the edges. All network components (nodes and edges) are mutually independent. These precedent hypotheses are intended to evacuate all sources of numerical useless complexity. As our main objective is to highlight the original characteristic of the proposed approach.

7

Sprężysto-tłumiąca więź kontaktowa w numerycznych symulacjach drgań układu pociąg – tor

Lalewicz Piotr, Bryja Danuta

Przegląd Komunikacyjny

|

2021

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R. 76, nr 6/7

14--21

PL

W sprzężonym układzie pociąg – tor, kontakt pomiędzy podukładami występuje na styku każdego koła z szyną. Najpopularniejszym obecnie modelem kontaktu stosowanym w symulacjach numerycznych drgań jest idealnie sprężysta, zlinearyzowana więź Hertz’a bazująca na teorii kontaktowej Hertz’a. W bogatszych wariantach modelu kontaktowego uwzględnia się dodatkowo dyssypację energii na styku koła z szyną. W literaturze brakuje porównań tych modeli wskazujących na skutki zastosowania konkretnego rozwiązania. Zasadniczym celem niniejszej pracy jest analiza porównawcza skutków zastosowania dwóch wybranych więzi kontaktowych w symulacjach numerycznych drgań układu pociąg – tor. Rozważono standardową zlinearyzowaną więź sprężystą typu Hertz’a i więź sprężysto-tłumiącą zdefiniowaną przez autorów, bazującą na tłumieniu histerezy. Skutki zastosowania tych więzi kontaktowych zbadano na podstawie porównania wyników symulacji pionowych drgań toru z nierównością progową, przez którą przejeżdża pociąg stanowiący zespół pojazdów kolejowych. Na podstawie wykonanych analiz numerycznych postawiono tezę, że zastosowanie modelu kontaktowego koło – szyna wzbogaconego o tłumienie histerezy jest sensowne wtedy, gdy badania są ukierunkowane na stan wytężenia toru i efekty zmęczeniowe w torze i pojeździe kolejowym. Stwierdzono ponadto, że pominięcie tłumienia w strefie kontaktu nieco zaniża prawdopodobieństwo wystąpienia utraty kontaktu, a więc nie prowadzi do prawidłowej identyfikacji tego zjawiska.

EN

In train – track coupled systems, interaction between subsystems occurs in wheel-rail contact. The most common contact model is perfectly elastic, linearized Hert’z spring. It has wide range of application in numerical simulations. In more detailed interaction models, the energy dissipation in wheel-rail contact is taken into account. There are no known comparisons of these models in the literature, that would indicate the effects of a specific solution application. In this paper, the main purpose is to analyze and compare the effects of two contact models in terms of numerical simulations of train – track vibrations. The reference contact model taken into account is linearized, perfectly elastic Hert’z spring. The second spring, proposed by the authors is enriched with viscous element based on hysteresis damping. Application of both models, and its effects were examined in plane, train – track vibrations simulations with threshold inequality excitation in the middle of the track length. Concluding from the analyzes performed, it was found that viscoelastic contact model application is important, when track stresses and fatigue are being investigated. In addition, it was found that neglecting the damping element in contact model reduces the probability of the wheel – rail contact loss phenomenon, and thus leads to incorrect identification of its occurrence.

8

Simulation and optimization of a new energy vehicle power battery pack structure

Ruan Guanqiang, Yu Changqing, Hu Xing, Hua Jing

Journal of Theoretical and Applied Mechanics

|

2021

|

Vol. 59 nr 4

565--578

EN

With the rapid growth in new energy vehicle industry, more and more new energy vehicle battery packs catch fire or even explode due to the internal short circuit. Comparing with traditional vehicles, the new energy vehicles industry should pay more attention to safety of power battery pack structures. The battery pack is an important barrier to protect the internal batteries. A battery pack structure model is imported into ANSYS for structural optimization under sharp acceleration, sharp turn and sharp deceleration turn conditions on the bumpy road. Based on the simulation, the battery pack structure is improved, and suitable materials are determined. Then the collision resistance of the optimized battery pack is verified, and the safety level is greatly improved. While ensuring the safety and reliability of the battery pack structure, it also reduces the weight to satisfy the lightweight design and complies with relevant technical standards.

9

Powered support in dynamic load conditions - numerical analysis

Masny Wojciech

Archives of Mining Sciences

|

2020

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Vol. 65, no. 3

453--468

EN

Tremors occur randomly in terms of time, energy as well as the location of their focus. The present state of knowledge and technology does not allow for the precise prediction of these values. Therefore, it is extremely important to correctly select a powered roof support for specific geological and mining conditions, especially in the case of areas where dynamic phenomena are often registered. This article presents information on rock burst hazard associated with the occurrence of rock mass tremors and their influence on a powered roof support. Furthermore, protection methods of a powered roof support against the negative effects of dynamic phenomena are discussed. As a result of an analysis the methodology, to determine the impact of dynamic phenomena on the powered roof support in given geological and mining conditions is presented.

10

Furniture use safety at early design stage

Majewski Adam

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

|

2019

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No. 108

84--92

EN

Furniture use safety at early design stage. This paper presents a virtual method of determining the usage safety of a bed frame. The aim of the study was to investigate the influence of different external loads dictated by standards on the newly designed bed structure. Furthermore, it was decided to take into consideration unusual ways of acting load. Finally, the test of dynamic load was carried out. The analysis was executed by means of Finite Element Method in Computer Aided Engineering software. Results of stress distribution and displacements were compared to previously investigated mechanical properties of the used materials, such as elastic plywood and pine wood rigidity. Based on compared data, the safe use of bed frame was determined. The numerical calculations performed proved that there are possibilities of design changes to improve user safety and/or reduce production costs while ensuring sufficient mechanical properties of the furniture. Conclusions of the analysis suggested a possibility to sub-optimize the tested solution.

PL

Bezpieczeństwo użytkowania mebla na wczesnym etapie projektowania. Zgodnie z Dyrektywą 2001/95/WE Parlamentu Europejskiego i Rady z dnia 3 grudnia 2001 r. w sprawie ogólnego bezpieczeństwa produktów wymaga się, aby sposób użycia wyrobu ani on sam nie stwarzał zagrożenia dla zdrowia i życia użytkowników. Dobór materiałów na elementy mebla i sposób ich połączenia stanowią, zatem kluczowe działania w kontekście inżynierskiego projektowania mebli. Jednym z zadań wieloetapowego procesu projektowania jest kosztowne wykonywanie prototypów z materiałów docelowych. Dzięki oprogramowaniu wspierającemu projektowanie inżynierskie - CAE, można dokonać wstępnej oceny wytrzymałości konstrukcji przez numeryczne obliczenia metodą elementów skończonych. W niniejszej pracy przedstawiono wirtualne symulacje sposobu obciążenia nowej konstrukcji łóżka, podjęte już na etapie przygotowania bryły 3D. Elementy modelowano, jako wykonane z drewna sosny zwyczajnej oraz sklejki elastycznej FUMA o grubościach 5 mm i 8 mm. Wartości sił oraz punkty ich przyłożenia dobrano na podstawie odpowiednich norm. Obciążenie przykładano także do potencjalnie newralgicznych węzłów konstrukcji. Przeprowadzono ponadto symulację dynamicznego obciążenia boku łóżka. Na podstawie uzyskanych wyników ustalono, że zaproponowana konstrukcja jest bezpieczna, bowiem naprężenia w obciążanych statycznie elementach nie przekraczają 50% wytrzymałości użytego materiału. Szczyt łóżka, pomimo relatywnie dużego ugięcia, nie wykazywał tendencji do poważnych deformacji i uszkodzenia. Ostatnią część pracy poświęcono suboptymalizacji analizowanej konstrukcji łóżka.

11

Unique information about lubricants

Voinov K. N., Esbulatova A. Z.

Mechanics and Mechanical Engineering

|

2018

|

Vol. 22, nr 1

143--152

EN

The positive and negative properties/characteristics of liquid and plastic lubricants are presented here in brief. General aim: to show the ways to improve the positive role of lubricants for mobile junctions, namely, for pairs of friction. At the same time, there are two devices which are represented to make the effective control both the quality and viscosity for lubricant as well. And the new very important effect with the organic lubricant was discovered. It is the electro-magnet property which helps to keep organic lubricant in a zone of friction constantly.

12

Oddziaływanie pojazdu na powłokę w obiektach gruntowo-powłokowych

Machelski C.

Przegląd Komunikacyjny

|

2017

|

R. 72, nr 9

12--17

PL

W pracy omówiono wyniki badań obiektów gruntowo-powłokowych poddanych obciążeniom pojazdami drogowymi i kolejowymi, zmieniającymi swoje położenie wzdłuż toru ruchu. Rozpatrywane są obciążenia quasi statyczne w ujęciu kroczącym i ciągłym (z minimalną prędkością przejazdu). Analizowano wpływy oddziaływań dynamicznych pojazdów w funkcji prędkości przejazdu. Rozpatrywane są ciężkie, przejazdy eksploatacyjne z małymi prędkościami. Odrębna grupą są przejazdy pasażerskich pociągów w przejazdach z dużymi prędkościami. W tym przypadku realizowane są symulacje numeryczne z wykorzystaniem złożonych modeli obiektów gruntowo-powłokowych. W pracy sprecyzowana jest specyfika (odmienność) efektów oddziaływań dynamicznych taboru kolejowego na obiekty gruntowo-powłokowe w odniesieniu do klasycznych mostów stalowych. Z przedstawianych wyników badań obiektów gruntowo-powłokowych widoczne jest korzystne współdziałanie nawierzchni kolejowej i podbudowy z powłoką z blachy falistej zanurzonej w zasypce gruntowej jak w nasypach kolejowych.

EN

The paper presents the results of soil steel structures tests under road and rail vehicles loads, which change their position along the track. Quasi static loads are considered in both stepping and continuous measurement method (with minimum travel speed). The impact of dynamic loads from vehicles as a function of vehicle speed was analyzed. Heavy, low-speed driving rides and as a separate group the passage of passenger trains in high speed journeys were considered. In this cases numerical simulations are performed using complex models of soil-steel structures. The specificity (difference) of dynamic effects from dynamic loads of rolling stock on soil-steel structures in relation to classic steel bridges is specified in the paper. The presented results from tests shows the favorable interaction of the railway tracks and substructures with the corrugated steel shell in the backfilling as in the railway embankments.

13

Decision Making in Crisis Management : Time Criticality Assessment

Eid M., Souza de Cursi E., Abdelkhalak E.

Journal of Polish Safety and Reliability Association

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2017

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Vol. 8, No. 1

13--22

EN

The paper is proposing a methodology for assessing the time-criticality in the scope of a crisis resulting from a cascade of disruptions of a set of Critical Infrastructures (CIs). The success of the management of the crisis depends on taking the good decisions and undertaking the corresponding actions at the good timing. Identifying time intervals for decisions and actions requires dynamic models capable to assess the crisis time evolution. While, measuring the “criticality” of different time-intervals requires the use of suitable metrics. Based on previous works for modelling cascade of CIs’ disruptions incorporating CIs dependency and vulnerability, the authors propose a methodology to assess the time-criticality and propose the appropriate metrics. The methodology is based on the idea of comparing the time-profile of a given cascade of disruptions between two configurations: unstressed and stressed CIs. The CIs become stressed under the action of a threat and combined with the dependency between CIs. The unstressed configuration represents a risk-noise. Two metrics are proposed in order to carry on the comparison between the time-profiles of the stressed and the unstressed CIs. The proposed metrics are: the time to attend 90% of the asymptotic occurrence probability and the time to attend the most probable occurrence rate, describing the cascade likelihood. An academic case is presented in order to demonstrate the applicability of the methodology and illustrate some interesting features.

14

Analiza oddziaływań dynamicznych profili z kompozytów węglowych na różne rodzaje wymuszenia

Deuszkiewicz P.

Mechanik

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2016

|

R. 89, nr 12

1926--1927

PL

W artykule przedstawiono analizę oddziaływań dynamicznych (np. występowania stanów krytycznych) w konstrukcji z kompozytu węglowo-epoksydowego na przykładzie wału maszynowego przy różnych rodzajach wymuszenia. Przeprowadzony eksperyment miał dać odpowiedź na pytanie, czy da się przewidzieć zachowania dynamiczne występujące w trakcie normalnej eksploatacji (wymuszenie kinematyczne) na podstawie doświadczeń wykonanych na stanowisku laboratoryjnym przy wymuszeniu realizowanym siłą harmoniczną lub impulsową.

EN

The article presents an analysis of dynamic interactions (e.g. occurrence of critical states) with the construction of carbon fiber composite (for example the drive shaft) for different types of excitation. Experiment was conducted to answer the question whether it is possible to predict the dynamic behaviour occurring during normal operation (force kinematic) based on the experiment made at the laboratory when the excitation was implemented as a harmonic or impulse force.

15

Modal analysis of real timber frame houses with different insulation materials

Szczepański M., Migda W., Jankowski R.

Advances in Science and Technology. Research Journal

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2016

|

Vol. 10, nr 31

215--221

EN

The aim of this article is to present the results of a numerical modal analysis of two actual structures of timber frame buildings and the different behaviour due to the used insulation material. One model of the timber structure was filled with mineral wool, while the other with polyurethane foam. During the modal analysis, eigenvalues for both models have been determined. The results of the analysis clearly show the increase of stiffness and damping properties of skeletal constructions achieved by the use of polyurethane foam as the skeleton filling. The numerical model was based on prior experimental test on real scale single frame elements, therefore the result can be assumed to be adequate.

16

Some applications of fractional calculus in modelling of accelerometer and pressure transducer

Pietruszczak D., Luft M., Lesiak P.

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

|

2015

|

Nr 47

147--150

EN

The paper outlines applications of fractional calculus for dynamic measurements while developing a method for description of transducer dynamic properties, which the authors consider to be the original and unique achievement of their work. The main objective of the paper is to show the implementation of a fractional calculus-based method that allows for description of dynamic properties of transducers of arbitrary orders (not only integer). The paper presents possibilities of using fractional calculus in dynamic measurements for modelling an accelerometer and a pressure transducer. Tests are executed in the MATLAB&Simulink environment. New methods of modelling transducers are important particularly in the case of the development of new technologies and materials the performance of which is beyond the scope of dynamic behaviour modelled by means of differential equations of integer orders. An example here can be a pair: a capacitor (integer order model) and supercapacitor (fractional order model).

PL

W artykule przedstawiono możliwości zastosowania rachunku różniczkowego niecałkowitych rzędów (ang. fractional calculus) do opisu właściwości dynamicznych akcelerometru i przetwornika ciśnienia dowolnych rzędów, co autorzy uważają za swoje oryginalne osiągnięcie w pracy naukowej. Badania symulacyjne wykonano w środowisku MATLAB&Simulink. Autorzy zakładają, że przyszłości właściwości dynamiczne modeli przetworników o nowych rozwiązaniach konstrukcyjnych i technologicznych będą wymagały opisu za pomocą rachunku różniczkowego niecałkowitych rzędów. Takie założenie, że „teoria” powinna wyprzedzać „praktykę” wydaje się być słusznym gdyż wielokrotnie sprawdzała się w przeszłości. Przykładem może być tutaj klasyczny kondensator i jego „ułamkowy” odpowiednik: superkondensator.

17

Dynamic diagnosis of conductive materials on the basis of force acting on the sensor made of permanent magnet

Szewczyk K., Walasek T., Kucharczyk Z.

Przegląd Elektrotechniczny

|

2015

|

R. 91, nr 12

221-223

EN

Sprawdzanie jakości drutu, blachy w czasie procesu wytwarzania sprawia problemy. Oddziaływanie dynamiczne ruchu w powiązaniu z polem magnetycznym wywołuje efekt prądów wirowych oraz sił. Wielkość siły oddziaływania może wskazywać na wady materiału pojawiające się w czasie procesu produkcji. Wykorzystanie tego zjawiska może pomagać w procesie kontroli jakości materiału. W pracy przedstawiono symulację takiego procesu oraz dokonano obliczeń sił i momentów występujących przy tego rodzaju procesie. Obliczeń dokonano w oparciu o środowisko ANSYS z wykorzystaniem metody elementów skończonych oraz tensorów naprężeń Maxwella.

18

Symulacje numeryczne zjawisk dynamicznych w układzie pantograf - sieć jezdna

Wątroba P., Duda S., Gąsiorek D.

Modelowanie Inżynierskie

|

2015

|

T. 23, nr 54

94--100

PL

W artykule przedstawiono komputerowe narzędzia i metodykę modelowania pozwalające symulować zachowanie pantografu z uwzględnieniem zjawiska kontaktu pomiędzy pantografem i siecią jezdną. Do tego celu wykorzystano środowisko Matlab/Simulink, w którym opracowano dynamiczny model pantografu w konwencji układów wieloczłonowych. Odkształcalny model sieci zbudowano z zastosowaniem metody elementów skończonych, a następnie opracowano model kontaktu z wykorzystaniem teorii Hertza, który opisuje interakcję pomiędzy pantografem a siecią jezdną. Ponadto w modelu zaimplementowano algorytm obliczający siłę aerodynamiczną oddziałującą na pantograf w zależności od wysokości uniesienia pantografu oraz prędkości jazdy. Przeprowadzone symulacje numeryczne pozwoliły wyznaczyć siły w punkcie kontaktu dla określonych warunków jazdy.

EN

The paper describes the modeling methodology and computer software which presents the simulation of the pantograph behavior. It considers also the contact between pantograph and the catenary. For this purpose author used the Matlab-Simulink environment, which has developed the dynamic model of pantograph by the dynamic multibody model convention. The deformable model was built using the Hertz theory, which describes the interaction between pantograph and the catenary of the vertical contact system. Furthermore, model implemented the algorithm which calculated the strength of aerodynamic forces in the pantograph. It depends on the amount of the pantograph elevation and its driving speed. The numerical simulations have designated the force at the point of contact for certain driving conditions.

19

Modelling and analysis of the technological processes using finite element method

Kukiełka L., Kukiełka K.

Mechanik

|

2015

|

R. 88, nr 3CD

317--340

EN

Paper presents the problem of modelling and analysis of metalworking processes. Technological processes were considered as a geometrical, physical and thermal boundary and initial value problem, with unknown boundary conditions in the contact zone. An incremental model of the contact problem between movable rigid or thermo-elastic body (tool) and thermo-elastic/thermo-visco-plastic-phases body (object) in updated Lagrange formulation, for spatial states (3D) was considered. The incremental functional of the total energy and variational, non-linear equation of motion of object and heat transfer on the typical step time were derived. This equation has been discretized by finite element method, and the system of discrete equations of motion and heat transfer of objects were received. For solution of these equations the explicit or implicit methods was used. The applications were developed in the ANSYS/LS-Dyna system, which makes possible a complex time analysis of the states of displacements, strains and stresses, in the workpieces in fabrication processes. Application of this method was showed for examples the modelling and the analysis of burnishing rolling, thread rolling and turning processes. The numerical result were verified experimentally.

PL

W artykule przedstawiono problematykę modelowania i analizy numerycznej procesów technologicznych obróbki metali. Proces te rozpatrzono jako geometrycznie, fizycznie i cieplnie nieliniowe zagadnienie brzegowopoczątkowe, z nieznanymi warunkami brzegowymi w obszarze kontaktu. Do opisu zjawisk nieliniowych, na typowym kroku przyrostowym, wykorzystano uaktualniony opis Lagrange'a, traktując narzędzie jako ciało sztywne lub termo-sprężyste natomiast przedmiot jako ciało termo-sprężyste/termo-lepko-plastyczne-fazowe. Równania ruchu obiektu i ciepła wyprowadzono wykorzystując rachunek wariacyjny. Otrzymane równania wariacyjne dyskretyzowano stosując aproksymację właściwą metodzie elementu skończonego. Dyskretne równania rozwiązano stosując jawne metody całkowania. Opracowano aplikacje w systemie ANSYS/LS-Dyna, które pozwalają na kompleksową analizę stanów przemieszczeń, odkształceń, naprężeń w dowolnym miejscu ciała i w dowolnej chwili realizacji procesu obróbki. Przedstawiono przykładowe wyniki obliczeń numerycznych stanów naprężeń i odkształceń wybranych procesów technologicznych: nagniatania, walcowania gwintów i toczenia. Wyniki obliczeń numerycznych weryfikowano eksperymentalnie.

20

Critical Infrastructures Protection (CIP) : coupled modelling for threats and resilience

Eid M., El-Hami A., Souza de Cursi E., Kołowrocki K., Kuligowska E., Soszyńska-Budny J.

Journal of Polish Safety and Reliability Association

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2015

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Vol. 6, No. 1

85--94

EN

Critical Infrastructure Protection (CIP) requires the development of models and tools able to describe and simulate the threats’ and the Critical Infrastructure’s (CI) dynamic behaviour. However, these modelling activities are very often carried out separately for threats and for CI behaviour. An effective assessment of the CI’s resilience and preparedness requires real coupled models of threats dynamic and CI’s one. The authors develop some basic ideas about coupled modelling in the sense of coupling the dynamics of the threat with that of the CIs, within a stochastic modelling approach. Such coupled dynamic models would enhance the effectiveness of our capabilities to assess CI’s resilience and to help in decision making for crisis management.