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  1. 7 International Journal of Applied Mechanics and Engineering
  2. 7 Journal of KONES
  3. 6 Mechanik
  4. 6 Przegląd Mechaniczny
  5. 5 Acta Mechanica et Automatica
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  1. 80 Graba M.
  2. 26 Bieniek A.
  3. 23 Mamala J.
  4. 11 Hennek K.
  5. 10 Prażnowski K.
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  1. 1 2020
  2. 1 2019
  3. 7 2018
  4. 9 2017
  5. 8 2016
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1
Content available The characteristics of selected triaxiality measures of the stresses for a C(T) specimen dominated by the plane strain state
Graba M.
International Journal of Applied Mechanics and Engineering
|
2020
|
Vol. 25, no. 1
52--74
EN
The paper presents a comprehensive analysis of the stress field and selected triaxiality parameters near the crack tip for C(T) specimen dominated by the plane strain state using the finite element method. It includes some theoretical information about elastic-plastic fracture mechanics, the basics of the FEM modeling and presentation of the numerical results. The FEM analysis includes calculations with large strain assumptions. The influence of the external load and crack length is discussed. Additional elements of the paper are a qualitative assessment of the size of plastic zones and the crack tip opening displacement.
2
Content available The characterization of the stress fields near a crack tip for a compact specimen for elastic-plastic materials dominated by the plane strain state
Graba M.
International Journal of Applied Mechanics and Engineering
|
2019
|
Vol. 24, no. 3
549--576
EN
The paper presents a comprehensive analysis of the stress field near a crack tip for a compact specimen dominated by the plane strain state using the finite element method. The analysis also includes the calculation of some parameters of in-plane constraints, both for small and large strain assumptions. It discusses the influence of the material characteristic, relative crack length and external load for the stress field, and the in-plane constraint parameter. The approximation formulas for some in-plane constraint parameters are presented.
3
Content available remote Analiza nośności granicznej wybranych pękniętych płyt spawanych – zagadnienia undermatching
Graba M.
Mechanik
|
2018
|
R. 91, nr 12
1144--1146
PL
Zaprezentowano rezultaty numerycznej weryfikacji nośności granicznej rozciąganych, spawanych płyt z dwustronnym pęknięciem w odniesieniu do formuł zaproponowanych w procedurach FITNET. Analiza dotyczyła wybranych przypadków geometrii płyty, a niedopasowanie materiału spoiny i materiału bazowego ograniczono do przypadków undermatching – gdy materiał spoiny jest słabszy od materiału bazowego płyty.
EN
The paper presents the results of numerical verification of the limit loads of DEN(T) welded plates, referring to the formulas proposed in the FITNET procedures. The analysis concerned on selected cases of geometry plate, and the mismatch of the weld and base material was limited to the cases of undermatching.
4
Content available Possibilities of using a wireless telemetry system of a recreational vehicle (off-road)
Graba M., Mamala J., Hennek K., Prażnowski K.
Journal of KONES
|
2018
|
Vol. 25, No. 3
197--203
EN
The development of electronic systems has significantly contributed to the rapid increase in the number of controllers working in vehicles, and thus the amount of data transferred between them. The large amount of information sent prevents the driver from directly mastering or understanding them, hence it was necessary to limit the displayed parameters on the instrument cluster to the most important ones, so that the driver can focus on driving. However, in motor sports and in various types of road tests or research, where the driver is supported by an additional team of engineers, information sent between vehicle controllers can prove extremely valuable. Most often, the whole staff of people responsible for conducted traction tests does not occupy the vehicle, so as not to disturb the conditions. Their analysis usually takes place in a designated service spot, in which case the parameters from the on-board data transmission network are usually transmitted by radio from the vehicle to the archiving system. Therefore, research into the development of wireless data transmission systems from vehicle controllers is also carried out at the Opole University of Technology. This article describes the possibilities of using a system built at the Opole University of Technology for wireless conduction of diagnostics and analysis of current operating parameters of a recreational All-Terrain Vehicle (ATV). In addition, in the designed system, it is also possible to connect external sensors to analyse parameters normally not registered during the course on normal vehicle operation.
5
Content available Device for control the valvetrain and cylinder pressure of a spark-ignition engine
Mamala J., Graba M., Bieniek A., Hennek K.
Journal of KONES
|
2018
|
Vol. 25, No. 3
339--346
EN
This article describes the method of controlling an electric magnetic linear actuator that moves an inlet valve of an internal combustion engine. Thanks to the use of the electric control of the inlet valve of the internal combustion engine, it was possible to implement a variable effective compression ratio of the operating power unit, adapting it to the current needs and engine load. In this design, valvetrain was modified by introducing an autonomous intake valve operation with the use of a specially designed electromagnetic actuator. The introduction of this system necessitated an additional modification of the intake camshaft. The control was carried out with the use of a real-time controller with a built-in FPGA unit. The proposed design of a system with an electromagnetic actuator will allow obtaining an additional degree of freedom in the control unit. Particular attention should be paid to registered values or air pressure in the intake stroke for a closed or partially opened throttle, which generates significant pumping losses. The use of an electromagnetic actuator in the intake can help reduce said losses.
6
Content available Comparative analysis of the fuel consumption of vehicles equipped with various types of automatic transmissions
Graba M., Mamala J., Bieniek A., Ulfik A.
Journal of KONES
|
2018
|
Vol. 25, No. 4
119--124
EN
The growing number of vehicles moving on Polish roads equipped with various types of automatic transmissions prompted the authors of this publication to carry out research to assess the impact of the use of this type of transmission on the fuel consumption of these vehicles. The presented article presents a comparative analysis of the fuel consumption of vehicles of different manufacturers equipped with automatic transmissions moving in specially prepared driving cycles for research purposes. In the developed driving cycle, the vehicle speed was gradually increased every 10 km/h, maintaining each speed for a period of at least 30 seconds in order to stabilize the measurement results. The tests were carried out for various load stages of the drive system. Load differentiation was made by simulating driving in the prepared cycle for simulated different slopes of the road. The tests were carried out on the MAHA MSR500 chassis dynamometer, and the obtained results for the vehicle moving in automatic mode, where the transmission controller selected the gear ratio according to the programmed algorithm, were compared with the vehicle's fuel consumption for the vehicle gear selected by the driver in the driving cycle. The control software used to test the chassis dynamometer allows taking into account the increasing resistance of traffic along with the increase of vehicle speed, which greatly approximates the simulated conditions in the laboratory to the conditions on the road. The main purpose of this publication is to check whether using automatic transmissions or other control algorithm of these gears can achieve a reduction in fuel consumption.
7
Content available Experimental and numerical analysis of fracture in 41Cr4 steel – issues of the stationary cracks
Graba M.
International Journal of Applied Mechanics and Engineering
|
2018
|
Vol. 23, no. 1
37--63
EN
This paper analyzes the process of fracture in 41Cr4 steel on the basis of experimental and numerical data obtained for non-propagating cracks. The author’s previous and latest experimental results were used to determine the apparent crack initiation moment and fracture toughness for the material under plane strain conditions. Numerical simulations were carried out to assess changes in the J-integral, the crack tip opening displacement, the size of the plastic region and the distribution of stresses around the crack tip. A complex numerical analysis based on the true stress-strain curve was performed to determine the behavior of 41Cr4 steel under increasing external loads.
8
Content available The influence of the exhaust system leak on the operating parameters of a turbocharged spark ignition engine
Hennek K., Graba M.
Autobusy : technika, eksploatacja, systemy transportowe
|
2018
|
R. 19, nr 6
468--472, CD
EN
Turbocharging of an internal combustion engine is the most common technique to improve an engines’ performance. In present it is not hard to meet vehicles on the road with turbocharged SI engines, which have a high mileage, and because of this fact there is a high risk of exhaust systems leak. This might have its influence not only on the emissions, but also on the vehicles performance. Thereby this dissertation shows the comparative analysis of the influence of exhaust system leak in the catalyzer input on the exhaust gasses composition in the catalyzer output and the operation parameters of an turbocharged SI engine. During the research some parameters were recorded and compared, e. g.: the engines power and torque, the injectors opening time, the oxygen sensors voltage signals in the input and in the output of the catalyzer, the concentration of harmful gasses in the exhaust tailpipe. The research was conducted with the use of a single roller MAHA MSR 500 chassis dynamometer. A series of torque measurements was performed. Under these measurements a simulation of the exhaust system leakage of a turbocharged SI passenger car engine was made. As a result three variations of the wideband oxygen sensor acting were reached. The wideband sensor is mounted between the turbocharger unit and the input of the catalyzer. In the test the influence of the leakage on the injector’s opening time and the composition of harmful exhaust substances were pointed.
PL
Układy turbodoładowania są obecnie najczęściej stosowanymi układami zwiększającymi moc silników spalinowych. Obecnie nietrudno spotkać na drodze pojazdy wyposażone w tego typu silniki ze znacznym przebiegiem, a co za tym idzie z podwyższonym ryzykiem wystąpienia nieszczelności w układach wylotowych spalin, mających wpływ nie tylko na powstającą emisję, ale również na parametry pracy tych silników. Stąd w pracy przedstawiono analizę porównawczą wpływu nieszczelności układu wylotowego na skład spalin na wyjściu z katalizatora oraz parametrów pracy turbodoładowanego silnika ZI. Podczas badań rejestrowano takie parametry jego pracy jak: moment obrotowy, czas otwarcia wtryskiwaczy, sygnały napięciowe sond lambda na wejściu i wyjściu katalizatora oraz stężenie substancji szkodliwych w spalinach. Badania przeprowadzono na jednorolkowej hamowni podwoziowej MAHA MSR 500, na której wykonano szereg pomiarów mocy silnika testowanego pojazdu. W ramach tych pomiarów dokonywano symulacji nieszczelności układu wydechowego turbodoładowanego silnika, w wyniku których uzyskano trzy warianty działania szerokopasmowej sondy lambda, zamontowanej pomiędzy zespołem turbosprężarki a katalizatorem spalin.
9
Content available Parametry pracy turbodoładowanego silnika ZI samochodu osobowego w warunkach nieszczelności układu wydechowego
Hennek K., Graba M.
Autobusy : technika, eksploatacja, systemy transportowe
|
2018
|
R. 19, nr 6
463--467, CD
PL
W artykule omówiony został wpływ nieszczelności układu wydechowego na parametry użytkowe oraz emisję substancji szkodliwych w spalinach turbodoładowanego silnika o zapłonie iskrowym samochodu osobowego. Dokonano analizy porównawczej wyników pomiarów uzyskanych na hamowni podwoziowej MAHA MSR500 w warunkach szczelności oraz sztucznego wytworzenia nieszczelności układu wydechowego w miejscu montażu szerokopasmowego czujnika stężenia tlenu w spalinach. Przedstawione dane odnoszą się między innymi do emisji toksycznych i nietoksycznych składników spalin, przebiegów mocy w układzie napędowym oraz chwilowych wartości współczynnika nadmiaru powietrza. W celu uzyskania danych wykonano szereg przejazdów pomiarowych według profilu prędkości cyklu jezdnego EUDC.
EN
Paper discussed the influence of exhaust system leakage on the utility parameters and toxic combustion products emission of a turbocharged passenger car spark ignition engine. A comparative analysis of the data gathered in the research carried out using the MAHA MSR 500 single roller chassis dynamometer was conducted, where the exhaust system was sealed and leaking in the area of the wideband oxygen sensor mounting bracket. The presented data refers to among others: the emissions of harmful gasoline oxidation products (HC, CO), the courses of power generated by the engine and the momentary values of excess air ratio. The EUDC driving cycle was used in the research.
10
Analysis of fuel consumption in real driving cycles
Hennek K., Kołodziej S., Graba M., Mamala J.
Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska
|
2017
|
z. 1/110
31--38
EN
This dissertation shows the analysis of the selected indicators of the work of drive system designated with the use of the Road Load Engine Simulator. Its original software enables digital and research station simulations. In a digital simulation, an internal-combustion engine is saved in a numerical form showing the speed and throttle position characteristics of temporal fuel consumption, torque, stream of emissions of harmful substances. This characteristics, in a binary form, using the "Look and Tabel" on a regular basis are loaded into the computer memory. Basing on a virtual vehicle, indicators of the drivetrain of a passenger car including Tank To Wheels chain (TTW) have been determined. Both synthetic and real driving cycles were analyzed during the study, whereas the velocity profile was reproduced using an auto driver. The simulation -results are summarized in a tabular and graphic form and expressed per kilometer of the distance covered.
PL
W pracy przedstawiono analizę wybranych wskaźników pracy układu napędowego wyznaczonych za pomocą Stanowiskowego Symulatora Obciążenia Drogowego Silnika. Autorskie oprogramowanie symulatora umożliwia symulację stanowiskowąoraz cyfrową, w której silnik spalinowy, jest zapisany w postaci charakterystyk prędkościowych przedstawiających czasowe zużycie paliwa, moment obrotowy, strumień emisji substancji szkodliwych. Charakterystyki te, w formie binarnej, za pomocą funkcji „Look and Tabel” na bieżąco wczytywane są do pamięci komputera. W oparciu o wirtualny pojazd wyznaczane są wskaźniki pracy układu napędowego samochodu osobowego obejmujące przebiegowe zużycie paliwa, energochłonność ruchu czy sprawność całego układu napędowego obejmującego łańcuch TTW (ang. Tank to Wheels). Podczas badań analizowano syntetyczne i rzeczywiste cykle jezdne, przy czym profil prędkości był odwzorowany przy użyciu automatycznego kierowcy, dla którego wyznaczono średnią prędkość i dynamikę cyklu. Wyniki symulacji zestawiono w postaci tabelarycznej oraz graficznej i odniesiono na kilometr przejechanej drogi.
11
Content available remote O kryteriach pękania materiałów sprężysto-plastycznych
Graba M.
Mechanik
|
2017
|
R. 90, nr 12
1174--1179
PL
Przedstawiono przegląd wybranych kryteriów pękania materiałów sprężysto-plastycznych. Kryteria te – jako jedne z wielu – mogą zostać wykorzystane do oceny rzeczywistej odporności na pękanie różnych materiałów konstrukcyjnych, o ile użytkownik dysponuje wymaganymi parametrami, definiowanymi z wykorzystaniem mechaniki pękania.
EN
The paper presents a brief overview of selected fracture criteria of elastic-plastic materials. These criteria, ones of many, can be used to assess the real fracture resistance of different construction materials, provided the user has the required parameters defined by the fracture mechanics.
12
Content available Nitrogen oxides emission estimator for a diesel engine use to reduce the emission of harmful substances in exhaust gas to environment
Graba M., Mamala J, Bieniek A., Hennek K.
Journal of KONES
|
2017
|
Vol. 24, No. 3
87--94
EN
This article reports the results of experimental and numerical analysis of emissions of nitrogen oxides in exhaust gas to the environment from a turbocharged diesel engine of a tractor. The problem of identifying nitrogen oxides emissions from the exhaust gases was formulated and subsequently solved, based on data gained from measurements. The results of estimation of nitrogen oxides emissions were verified on the basis of research on a test object. The object of the study and a non-linear static model of nitrogen oxides emission were also described for two systems – with and without exhaust gas recirculation. The article demonstrates that the use of an adequately selected mathematical model can lead to the estimation of emissions of nitrogen oxides contained in the exhaust gas of diesel engines in an off-road vehicle. The created model can be used to control the valve of the exhaust gas of recirculation system and so reduce the emission of harmful substances to the environment. The presented research results show the comparison of estimated and measured nitrogen oxides concentration. The estimated value from the mathematical model concentration is about from 0.7 s to 1 s earlier than the value measured by the sensor, therefore the exhaust gas recirculation system could be controlled accordingly before nitrogen oxides are formed.
13
Content available Comparative analysis of the operating indexes of manually and automatically controlled passenger car powertrain system at variable load states
Graba M., Mamala J., Bieniek A., Hennek K.
Journal of KONES
|
2017
|
Vol. 24, No. 4
39--46
EN
This article reports the results of a study into operating parameters of a system consisting of an SI engine and a powertrain in a Fiat Panda passenger car in the conditions of a variable load. The analysis was primarily concerned with the variability of fuel consumption resulting of the changing load applied to the driving wheels in the conditions of a test performed on chassis dynamometer for manual and automatic controlled transmission gear change The test bench included a dedicated driving cycle, which was developed as cycle with periodically changed constant linear speed of the car every 10 km/h. According to the vehicle set speed, the load on its wheels was determined by the basic resistance as rolling resistance, air resistance and resistance corresponding to road inclination. Each period of a drive cycle corresponding to steady state driving gave the average instantaneous values of drive system performance indicators. The waveforms of these indicators were recorded and then averaged and presented as representative points of the powertrain system that were analysed. The focus of the study involved the identification of the points characterized with the minimum specific fuel consumption and impact of type of powertrain control on emission of CO2 from passenger car SI engines.
14
Content available On the parameters of geometric constraints for cracked plates under tension – three-dimensional problems
Graba M.
International Journal of Applied Mechanics and Engineering
|
2017
|
Vol. 22, no. 4
901--919
EN
This paper provides a comparative analysis of selected parameters of the geometric constraints for cracked plates subjected to tension. The results of three-dimensional numerical calculations were used to assess the distribution of these parameters around the crack front and their changes along the crack front. The study also involved considering the influence of the external load on the averaged values of the parameters of the geometric constraints as well as the relationship between the material constants and the level of the geometric constraints contributing to the actual fracture toughness for certain geometries.
15
Content available A numerical analysis of selected elastic-plastic fracture parameters for DEN(T) plates under plane strain conditions
Graba M.
International Journal of Applied Mechanics and Engineering
|
2017
|
Vol. 22, no. 1
49--80
EN
This paper provides a numerical analysis of selected parameters of fracture mechanics for double-edge notched specimens in tension, DEN(T), under plane strain conditions. The analysis was performed using the elastic-plastic material model. The study involved determining the stress distribution near the crack tip for both small and large deformations. The limit load solution was verified. The J-integral, the crack tip opening displacement, and the load line displacement were determined using the numerical method to propose the new hybrid solutions for calculating these parameters. The investigations also aimed to identify the influence of the plate geometry and the material characteristics on the parameters under consideration. This paper is a continuation of the author’s previous studies and simulations in the field of elastic-plastic fracture mechanics.
16
Content available The influence of the throttle inclination characteristics of a SI engine on fuel consumption in driving cycles
Hennek K., Graba M., Mamala J.
Combustion Engines
|
2017
|
R. 56, nr 3
78--83
EN
This dissertation shows the analysis of the selected indicators of the work of a passenger vehicle drivetrain designated with the use of the Road Load Engine Simulator. In a digital simulation, an internal – combustion engine is saved in a form of numerical speed characteristics in the computers memory. Basing on a virtual vehicle, some indicators of the drivetrain of a passenger vehicle have been determined, while driving with five electronic throttle inclination regulator settups. The simulation results of e.g., throttle repeal speeds and fuel consumtion are summarized in a tabular and graphic form and some of them are expressed per 100 kilometer of the distance covered. Both synthetic and real driving cycles were analyzed during the study and their influence on the egines fuel consumption was also shortly described.
17
Content available Impact of EGR control at in-cylinder pressure and ecological properties of CI off-road vehicle engine
Bieniek A., Mamala J., Graba M., Hennek K.
Combustion Engines
|
2017
|
R. 56, nr 3
88--95
EN
An attempt has been made to clarify the effect of wide-ranging control of the exhaust gas recirculation system on the cylinder pressure and ecological engine performance. This publication contains the results of tests performed on the CI (compression ignition) engine of the off-road vehicle mounted on the test bench. The study was based on advanced EGR control with a proportional valve and a very efficient exhaust gases cooling system. Analysis of the test results is based on the cylinder pressure and the concentration of NOx and PM components at exhaust gases. The study included the influence of the exhaust gas recirculation system control on parameters such as differential pressure, MBF, and relative NOx and PM emissions. As demonstrated by the analysis conducted, the EGR valve control method and the exhaust gas cooling intensity significantly affect the cylinder pressure and its ecological performance.
18
Content available Proposal of the hybrid solution to determining the selected fracture parameters for SEN(B) specimens dominated by plane strain
Graba M.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2017
|
Vol. 65, nr 4
523--532
EN
In the paper, new hybrid (numerical-analytical) methods to calculate the J-integral, the CTOD, and the load line displacement are presented. The proposed solutions are based on FEM calculations which were done for SEN(B) specimens dominated by plane strain condition. The paper includes the verification of the existing limit load solution for SEN(B) specimen with proposal of the new analytical formulae, which were used for building hybrid equations for determining three selected fracture mechanics parameters.
19
Bezprzewodowa diagnostyka pojazdu
Prażnowski K., Graba M., Hennek K., Mamala J.
Transport Przemysłowy i Maszyny Robocze
|
2016
|
Nr 1
53--56
PL
Rozwój układów i elementów elektronicznych we współczesnych pojazdach oraz złożoność poszczególnych jego podzespołów sprawia, że naprawa współczesnych samochodów bez użycia zewnętrznego systemu diagnostycznego jest praktycznie niemożliwa. Coraz to więcej elementów konstrukcji pojazdów do tej pory czysto mechanicznych zastąpionych zostaje przez podzespoły mechatroniczne, a więc wyposażone w dodatkowe elementy i czujniki elektryczne. Rozwiązania te w znacznym stopniu przyczyniają się do zwiększenia bezpieczeństwa i komfortu poruszających się po drodze [8]. Rozwój mikroelektroniki w dużym stopniu przyczynił się również do zwiększenia mocy jednostek napędowych oraz poprawy emisji substancji szkodliwych do środowiska naturalnego. Oczywiście należy tutaj wspomnieć, a nawet szczególnie zaznaczyć, że wszystkie dodatkowe systemy stosowane we współczesnych pojazdach nie potrafią oszukać praw fizyki i zapewniają poprawę wskaźników bezpieczeństwa jedynie w pewnych granicach.
EN
This paper presents a wireless on-board diagnostics system for a vehicle that measures and records the selected parameters of the internal combustion engine and the acceleration of the body. The measurements are sent to a computer on-line, using the 868MHz frequency band. Uploaded information can be stored on disk and visualized using a special application running on a PC.
20
Analiza sygnału przyspieszenia masy resorowanej i nieresorowanej samochodu osobowego pod kątem identyfikacji poziomu niewyrównoważenia koła ogumionego
Prażnowski K., Mamala J., Bieniek A., Graba M.
Transport Przemysłowy i Maszyny Robocze
|
2016
|
Nr 1
48--51
PL
Koło ogumione samochodu w rzeczywistych warunkach eksploatacyjnych może wywoływać drgania, wynikające z niejednorodności budowy opony, bicia kół oraz ich niewyrówoważenia [3, 5, 6, 10]. Wystąpienie nierównoważenia koła, wynikające z nierównomiernego rozkładu masy powoduje podczas jazdy powstanie siły wymuszającej, którą opisuje równanie (1).
EN
In order to verify the function forces the body vibrations induced by unbalanced mass of well-known pneumatic wheel. Acceleration measurement was conducted unsprung weight and unsprung vehicle tested using a chassis dynamometer. This allowed for testing stimulate the behavior of the vehicle in traffic conditions free from interference unevenness of the road. For the analysis of the recorded signal from the acceleration sensor used in the selected spectral methods.
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