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Tytuł:
Identification of ODS and dynamics characteristics of chain saws
Identyfikacja ODS oraz charakterystyka dynamiczna pilarek łańcuchowych
Autorzy:
Kromulski, J.
Pawlowski, T.
Zembrowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/52694.pdf
Data publikacji:
2010
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Drewna
Tematy:
chain saw
vibration
deflection
operational deflection shape
ODS zob.operational deflection shape
identification
dynamics
measurement
stationary operating condition
noise
Opis:
This article presents methods of identification of dynamics characteristics of chain saws. These methods can be successfully used in the process of identification of resonant frequencies and visualisation of ODS of chain saws. Vibration measurements were done using Laser Doppler Vibrometry. Some examples of identification of dynamics characteristics of chain saws and their operational deflection shapes are presented below.
Przedstawiono wyniki badań charakterystyki dynamicznej pilarki łańcuchowej. Pomiarów wibracji dokonano z wykorzystaniem techniki laserowej. Przeprowadzono analizę modalną układu. Zaprezentowano przykłady ODS (Operational Deflection Shapers) prowadnicy pilarki łańcuchowej.
Źródło:
Drewno. Prace Naukowe. Doniesienia. Komunikaty; 2010, 53, 183
1644-3985
Pojawia się w:
Drewno. Prace Naukowe. Doniesienia. Komunikaty
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metoda uwzględniania wartości ugięć poza zakresem nomogramu przy projektowaniu wzmocnienia konstrukcji nawierzchni
Method of taking into account deflection values beyond nomogram during pavement strengthening design
Autorzy:
Firlej, S.
Woszuk, A.
Powiązania:
https://bibliotekanauki.pl/articles/143454.pdf
Data publikacji:
2013
Wydawca:
Stowarzyszenie Inżynierów i Techników Komunikacji Rzeczpospolitej Polskiej
Tematy:
nomogram
ugięcie
wzmocnienie
deflection
strengthening
Opis:
Jedną z metod projektowania wzmocnienia nawierzchni jest metoda ugięć. Jak się jednak okazuje sposób ten nie zawsze jest możliwy do zastosowania. W artykule przedstawiono metodę określania grubości nakładki wzmacniającej, na podstawie ugięć, gdy szukana grubość warstwy tłucznia znajduje się poza granicznymi krzywymi na nomogramie.
One way to strengthen the pavement design is the method of deflections. As it turns out, this method is not always possible to apply. This paper presents a method for determining the thickness of the overlay reinforcement, based on deflection when looking for breakstone layer thickness is outside the boundary curves in the nomogram.
Źródło:
Drogownictwo; 2013, 10; 314-318
0012-6357
Pojawia się w:
Drogownictwo
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of a piezo-elastic restrictor using a capacitive shunt
Autorzy:
Kekana, M.
Badur, J.
Powiązania:
https://bibliotekanauki.pl/articles/1954087.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
passive control
piezo-elastic
deflection
Opis:
The study investigates the control of structural response using collocated piezoelectric elements mounted on both sides of beam. A capacitive shunt is introduced into the circuitry to provide passive control of the beam's configuration. The energy method is used to develop the structure's governing equations. In order to select the appropriate electrostatic relations for the material, i.e. conductor or insulator material, the free charge rearrangement time is used. The effects of the capacitive shunt are introduced into the electrostatic relations using additive decomposition of capacitance. As an application of the model, a piezo-elastic beam restrictor using a capacitive shunt is investigated. Numerical results show that the capacitive shunt can effect passive control of the configuration of the beam.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 3; 377-384
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical modelling of elastic deflection of a tubular cross-section
Autorzy:
Zastempowski, M.
Bochat, A.
Powiązania:
https://bibliotekanauki.pl/articles/258496.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
mathematical modelling of elastic deflection
tubular elements
deflection of ring under action of external forces
Opis:
Cutting a tubular element into thin rings is an operation often used in engineering processes. Total work of the cutting consists of that necessary for initial deflection of cut material and the cutting work itself. This paper presents mathematical models which describe deflection of cross-section of a single tubular element as well as a single layer of tubes under action of external forces ( acting and reacting ones). The deflection concerns end part of tube hence the cutting object model has been reduced to a thin ring. Results of calculation by using the developed models are presented for selected materials of tubular elements, which are commonly used for structures of the kind; moreover , they are prepared in a form of dimensionless diagrams, that makes it possible to use them for an arbitrary material.
Źródło:
Polish Maritime Research; 2015, 2; 93-100
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Overhead travelling crane construction deflection measurements with telematic approach
Autorzy:
Hyla, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/242897.pdf
Data publikacji:
2019
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
crane bridge deflection
total station
telematics
Opis:
Transport has always been a fundamental impulse for the development of civilization. Issues related to the regularity of operation of technical systems, in the last decade have become important issues being considered from both the point of view, as well as economics. Today the major threat in the operational reliability constitutes intensification of the machine and equipment use leading to excessive degradation. In automated manufacturing processes where the material handling operations are realized by the cranes, the safety as both devices and operating people constitute important factor. The main purpose of the article was focused on the set of issues including the material handling devices (MHD) reliability shaping problem especially presents work in progress towards development the MHD condition assessment system with using telematic approach. In the article author, special care was enclosed to MHD devices with strength human factor interaction and relatively large construction, so the overhead travelling crane was chose. The object of the statement constitutes an attempt of collecting the knowledge concerning a possibility of use modern measurement systems to monitoring crane bridge deflection. All tests and considerations were conducted on the double girder overhead travelling crane with hosting capability 1000 kg and bridge span 8000 mm.
Źródło:
Journal of KONES; 2019, 26, 3; 53-60
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Experimental Setup Parameters on Ultrasonic Assisted Micro-Upsetting
Autorzy:
Presz, W.
Powiązania:
https://bibliotekanauki.pl/articles/353082.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
microforming
ultrasonic
dynamic effect
elastic deflection
Opis:
The progressive development of miniature systems increases the demand for miniature parts. Reducing the size of manufactured components on one hand is a serious challenge for traditional technologies, but on the other hand, mainly by removing the energy barrier opens the possibility of using other unconventional techniques. A good example is the ultrasonic excitation of the punch during the micro-upsetting process. The anti-barreling phenomenon and dependent on the amplitude of vibrations, intensive deformation of the surface layers in contact with the tools at both ends of the sample was noted. Based on the measured strains and stresses, an increase in temperature in the extreme layers to approx. 200°C was suggested. By adopting a simplified dynamic model of the test stand, the possibility of detaching the surface of the punch from the surface of the sample was demonstrated.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 1; 423-431
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Modern CNC Milling with a Compensation of Cutting Tools and Thin-Walled Workpiec Deflections
Autorzy:
Polzer, A.
Dufkova, K.
Pokorny, P.
Powiązania:
https://bibliotekanauki.pl/articles/99493.pdf
Data publikacji:
2015
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
milling
CNC
deflection
surface quality
prediction
Opis:
Accuracy of machined components is one of the most critical considerations for any manufacturer. However, when milling the radial force deflects the cutting tool and workpiece. It affects the precision and quality of machined surfaces. The extent of the deviations can be predicted in various mathematical models. Thus, the errors can be compensated in NC programme effectively. So it is possible to machine with high cutting conditions, and also a high quality of machined surface can be achieved. In this paper are predicted deflection of milling tools and thin-walled workpiece. The experimental results show that the overall error in the flexible milling can be captured and predicted with very high accuracy.
Źródło:
Journal of Machine Engineering; 2015, 15, 3; 33-40
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Static electromechanical characteristics of piezoelectric converters with various thickness and length of piezoelectric layers
Autorzy:
Mieczkowski, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/387138.pdf
Data publikacji:
2019
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
piezoelectric bender
constitutive equations
deflection
electromechanical characteristics
Opis:
The paper presents the analysis of electromechanical characteristics of piezoelectric converters subjected to an electric field and mechanical load. The analyses were performed based on a method consisting implementation of special segments responsible for electrical boundary conditions to a homogeneous beam. Constitutive equations were developed, allowing one to obtain static electromechanical characteristics for piezoelectric actuators with freely defined boundary conditions and geometry. Moreover, based on constitutive equations obtained, a particular solution for cantilever transducer subjected to concentrated force has been developed. The resulting analytical solution was compared with the data available in the literature, and the developed FEM solution. Furthermore, the influence of factors such as relative length, thickness and location of particular piezoelectric layers on electromechanical characteristics of the transducer was defined.
Źródło:
Acta Mechanica et Automatica; 2019, 13, 1; 30-36
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the side deflection of the saw band of a joinery band saw influenced by the selected technical and technological factors
Autorzy:
Krilek, Jozef
Kuvik, Tomáš
Kováč, Ján
Melicherčík, Ján
Powiązania:
https://bibliotekanauki.pl/articles/409900.pdf
Data publikacji:
2020
Wydawca:
STE GROUP
Tematy:
band saw
saw band
stability
side deflection
Opis:
The paper focuses on measuring and evaluating the impact of selected technical and technological factors - the height of adjustable guides and stretching force - on the side deflection of the saw band of a joinery band saw. There is a detailed description of the ways the side deflection can be measured. In order to find out the intensity of the stretching force was used portable tension meter SANDVIK 5000, enabling to check the tensile stress in the saw blades of a gang saw or in the saw bands of a band saw. The actual experiment was conducted on a joinery band saw, at the cutting rate vc = 15 m·s-1. The results of the measurements confirmed the theoretical assumption of the impact of the selected technical and technological factors on the stability of the saw band, where the side deflection decreases with increasing stretching force and increases with increasing height of the guides. The stability of the saw band affects the quality of the surface to be treated, thus saving the cost of machining the workpiece and making work productivity more efficient.
Źródło:
Management Systems in Production Engineering; 2020, 3 (28); 148-153
2299-0461
Pojawia się w:
Management Systems in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monitoring of deep foundation deflection in model experiments by means of a magnetic method: theoretical study
Autorzy:
Wtorek, J.
Kurałowicz, Z.
Truyen, B.
Powiązania:
https://bibliotekanauki.pl/articles/241303.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
pile deflection
measurement
magnetic method
inverse problem
Opis:
In this paper, a new contact-free method for monitoring the displacement of buried foundations, with application to model (laboratory) studies, is considered. This method is based on the measurement of the magnetic induction amplitude created by a magnetic dipole attached to the construction. An array of sensing coils, located distantly, measures the changes in magnetic induction amplitude invoked by displacement of the signal source. The forward and inverse problems are formulated. Reconstruction of the source displacement is performed for synthetic data, both contaminated and uncontaminated by noise. It has been found that the reconstruction of displacements as small as 0.001 m is possible for distances between signal source (transmitting coil - magnetic dipole) and coil array of 0.5 m, even for data contaminated by noise.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2004, 51, 3; 225-241
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Conconi Test - Searching for the Deflection Point
Autorzy:
Hnizdil, Jan
Skopek, Martin
Nosek, Martin
Louka, Oto
Musalek, Martin
Heller, Jan
Powiązania:
https://bibliotekanauki.pl/articles/1922199.pdf
Data publikacji:
2019-08-07
Wydawca:
PPHU Projack Jacek Wąsik
Tematy:
anaerobic threshold
heart deflection point
heart rate
Opis:
The Conconi Test (CT) is an incremental exercise test characterized by stages of equal intensity. For analysis speed (S) and HR (heart rate) are used. The deflection point of the HR/S graph marks the point where the linear relation between S and HR changes to a curvilinear one. As Conconi stated HR at deflection point represents anaerobic threshold (AT) value. Purpose of this study was to extend our previous research dealing with reliability and validity aspects of CT. Material and Methods: During 10 years (2007-2017) we tested 2 500 subjects using Conconi protocol. Tested were mainly football players and smaller number of runners (long distance and cross country) different ages and fitness level. Some subjects were tested repeatedly during the years. Initial speed of the running treadmill test was determined in the range of 10 to 12 km·h-1, according subjects age and fitness level. Speed was increased gradually every 150 m of 0.5 km·h-1 to the maximum speed when further increases were impossible. HR was recorded at every 150 meters. From a graphical representation dependence HR on increasing running speed we tried to find apparent diversion from the curve of linearity, labeled by Conconi as "deflection point" (DP). Simultaneously respiration values were recorded. From these respiration data we determined the ventilatory threshold (VT2) as a metabolic marker of the onset of blood lactate accumulation. Results: We found 6 types of response HR to increasing speed. a) regular DP; b) linear regression r ≥ 0.98 - no DP; c) linear regression r < 0.98 - no DP; d) inversion character of deflection point; e) DP not corresponding with value of ANP; f) more than one DP. As an AT predictor compared with VT2, Conconi test overestimated this value (0.5 km·h-1). Conclusion: Using of Conconi test as a predictor of ANP has a limitation. ANP values determined by CT are overestimated (0.5 km·h-1). Test stability of CT is very low and there is evidence that DP is not 100% repeated physiology phenomena.
Źródło:
Physical Activity Review; 2019, 7; 160-167
2300-5076
Pojawia się w:
Physical Activity Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The constituent equations of piezoelectric cantilevered three-layer actuators with various external loads and geometry
Autorzy:
Mieczkowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/279842.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
piezoelectric bender
constitutive equations
deflection
analytical solutions
Opis:
This paper presents test results for deformation conditions of three-layer, piezoelectric cantilever converters subjected to various electrical and mechanical boundary conditions. A general solution has been developed based on implementation of piezoelectric triple segments (PTS) to the beam. A working mechanism and conditions for strain of the PTS segment have been determined. Basing on the general solution, for the cantilever actuator subjected to an external force (of single and dual PTS segments) and a uniform load (of single PTS segment), particular solutions have also been developed. Moreover, dimensionless frequencies of the oscillating motion for the analyzed converters have been determined. In the next step, the influence of such factors as length, quantity and position of PTS segments, their relative stiffness and unit weight on values of the obtained frequencies of vibration have been defined. The resulting analytical solutions have been compared with the developed FEM solution.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 1; 69-86
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical and practical methodology for recognizing the road surface structure
Autorzy:
Firlej, Stefan
Dębiński, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/391207.pdf
Data publikacji:
2018
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
road surface
backcalculation
dynamic deflection
road durability
Opis:
A recognition indicator of the possibility of further use of the road during transferring transport loads are changes in the condition of the road surface. If the surface condition indicates incorrect parameters of its equality, rutting, or cracks, the road durability is qualitatively assessed. In this case, the actual load capacity rating and possible reconstruction of the structure begins. Values of dynamic defl ections can be used to recognize the modulus of elasticity and thus the possibility of assessing the durability of a structure. The mechanistic method is used to dimensioning the structure due to the movement planned. It allows a fl exible approach to further construction, giving the opportunity to assess whether part or all of it should be left or apply an additional layer to meet future requirements. The elastic modulus needed for this pavement structure design method for existing layers has been recognized by identifi cation as backcalculation methodology that have been used for many years.
Źródło:
Budownictwo i Architektura; 2018, 17, 4; 35-45
1899-0665
Pojawia się w:
Budownictwo i Architektura
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of a MEMS hybrid thermo-PZT micro actuator
Autorzy:
Pourrostami, H.
Viliani, N. S. K.
Powiązania:
https://bibliotekanauki.pl/articles/280114.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
hybrid micro actuator
thermo-piezoelectric
deflection
force analysis
Opis:
The current study presents an analytical model for a MEMS cantilever based hybrid thermo- -piezoelectric micro actuator. The micro actuator structure consists of a unimorph type bending piezoelectric beam and a passive layer which uses the thermal bimorph principle. Primarily, under electrical and thermal loadings, the governing equations of motion are derived. After verification of the results, the deflection analysis of the micro actuator is performed. Moreover, the equivalent force at the actuator tip is obtained. To provide efficient optimization, the effects of the micro actuator geometrical and materials properties on the actuator tip deflection and force are investigated.
Źródło:
Journal of Theoretical and Applied Mechanics; 2016, 54, 4; 1309-1318
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interaction between matrix crack and elliptic inclusion under dynamic loadings
Oddziaływanie eliptycznego wtrącenia ze szczeliną w osnowie kompozytu podczas dynamicznego obciążania
Autorzy:
Li, Y
Ou, Z.
Duan, Z.
Huang, F.
Powiązania:
https://bibliotekanauki.pl/articles/280183.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
interface
fracture toughness
crack deflection/penetration
granule composites
Opis:
The strain-rate effects on the interaction between a matrix crack and an elliptic inclusion in granule composites under dynamic tensile loadings are investigated numerically. It is found that the crack deflection/penetration behavior depends on the relative strength and local curvature of the interface as well as the loading-rate (or strain-rate). For a certain interfacial strength, there exists a critical strain-rate above which the crack can penetrate across the interface; otherwise, the crack deflection occurs. Moreover, the critical strain-rate is found to be dependent only on the local curvature of the interface near the crack tip regardless of the size and shape of the elliptic inclusions.
W pracy przedstawiono rezultaty symulacji numerycznych wpływu szybkości zmian stanu naprężenia na interakcje pomiędzy szczeliną w osnowie i eliptycznym wtrąceniu w kompozycie granulkowym poddanym dynamicznemu obciążeniu rozciągającemu. Stwierdzono, że odkształcenie i (lub) penetracja szczeliny zależy od względnej wytrzymałości oraz lokalnej krzywizny powierzchni kontaktu pomiędzy wtrąceniem a osnową. Wykazano także ich zależność od tempa zmian obciążenia (lub odkształcenia). Zauważono, że przy pewnym poziomie wytrzymałości powierzchni kontaktu pojawia się krytyczna wartość tempa zmian odkształcenia, powyżej której szczelina propaguje w poprzek powierzchni kontaktu, w przeciwnym razie ugina się. Zgodnie z wynikami badań, krytyczna wartość szybkości zmian odkształcenia okazała się zależna wyłącznie od miejscowej krzywizny powierzchni kontaktu przy wierzchołku szczeliny, bez względu na rozmiar i kształt eliptycznego wtrącenia.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 327-337
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strength and buckling of sandwich beams with corrugated core
Wytrzymałość i stateczność belek trójwarstwowych z rdzeniem falistym
Autorzy:
Magnucki, K.
Jasion, P.
Krus, M.
Kuligowski, P.
Wittenbeck, L.
Powiązania:
https://bibliotekanauki.pl/articles/280851.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
sandwich beam
corrugated core
strength
elastic buckling
deflection
Opis:
The subject of the paper is a sandwich beam with a crosswise or lengthwise corrugated core. The beam is made of an aluminium alloy. The plane faces and the corrugated core are glued together. Geometrical properties and rigidities of the beams are described. The load cases investigated in the work are pure bending and axial compression. The relationship between the applied bending moment and the deflection of the beam under four-point bending is discussed. The analytical and numerical (FEM) calculations as well as experimental results are described and compared. Moreover, for the axial compression, the elastic global buc kling problem of the analysed beams is presented. The critical loads for the beams with the crosswise and lengthwise corrugated core are determined. The comparison of the analytical and FEM results is shown.
Przedmiotem pracy są belki trójwarstwowe zrdzeniem falistym. Poszczególne warstwy belek wykonane są ze stopu aluminium i połączone klejem. Wyróżniono dwa kierunki pofałdowania: wzdłużny i poprzeczny. Opisano geometrię przekroju poprzecznego i wyznaczono sztywności belek. W pracy rozpatrzono dwa przypadki obciążenia. Pierwszy z nich to czyste zginanie realizowane poprzez tak zwane zginanie czteropunktowe. Dla tego typu obciążenia zbadano zależność między przyłożonym momentem gnącym a ugięciem belki. Dla drugiego przypadku obciążenia, osiowego ściskania, omówiono problem globalnej stateczności sprężystej i wyznaczono obciążenia krytyczne. Ponadto zaprezentowano porównanie wyników uzyskanych z zaproponowanego modelu analitycznego z wynikami otrzymanymi z metody elementów skończonych i z badań laboratoryjnych.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 1; 15-24
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculation of the dynamic characteristics of ship’s aft stern tube bearing considering journal deflection
Autorzy:
Yang, Hongjun
Li, Jun
Li, Xiaolong
Powiązania:
https://bibliotekanauki.pl/articles/259603.pdf
Data publikacji:
2020
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
journal deflection
aft stern tube bearing
dynamic characteristic
Opis:
Dynamic properties are vital for the working reliability of aft stern tube bearings. However, the determination of such properties currently involves several simplifications and assumptions. To obtain its dynamic characteristics accurately, the aft stern tube bearing was divided into several bearing segments. The oil film reaction force was considered in the calculation of shaft alignment, and the journal deflection and actual oil film thickness were obtained accordingly. Subsequently, the perturbed Reynolds equation was solved using the finite difference method when the dynamic characteristics of journal bearings with finite width were evaluated. Then, a calculation program was developed and verified by comparing with the results of other studies. Finally, the dynamic characteristics were calculated under different revolutions. The results showed that the stiffness at the vertical direction of the aft stern tube bearing was several times that of the horizontal direction and varied with the revolutions of the shafting system. These findings can provide the foundation for the precise calculation of the journal trajectory under dynamic conditions, as well as for the evaluation of the oil film thickness. Moreover, the results led to favorable conditions for the accurate calculation of the shafting whirling vibration.
Źródło:
Polish Maritime Research; 2020, 1; 107-115
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydropneumatic suspension testing of a wheeled armoured personnel carrier
Autorzy:
Hryciów, Zdzisław
Rybak, Piotr
Wojciechowski, Michał
Wachowiak, Przemysław
Kalicki, Bartosz
Powiązania:
https://bibliotekanauki.pl/articles/24200841.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
hydropneumatic suspension
polytropic process
spring characteristic
static deflection
Opis:
The purpose of this study was to determine the effect of gas pressure and temperature on the spring characteristic of a HP strut used in a wheeled armoured personnel carrier. The research was performed based on a simulation model. Data to validate the model were obtained during experimental tests. The results indicate, among other things, that the friction generated in the seals is an important source of resistance force. Comparison of the simulation results with the measured characteristics indicates a proper modelling of the strut operation. Simulation studies have indicated that it is easy to modify the required suspension parameters by adjusting the initial gas pressure. A linear effect of pressure on static deflection can be assumed. Temperature has a strong influence on the spring characteristic. When it changes, significant changes in vehicle height are observed due to the lack of a compensation system. The temperature changes are not only due to changes in ambient temperature, but also by intense heating of the HP struts caused by the vehicle moving over rough terrain.
Źródło:
Eksploatacja i Niezawodność; 2023, 25, 2; art. no. 162497
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Longitudinal shear in composite deck slabs using corrugated steel sheets
Autorzy:
Alkurayshi, Hakim S. M.
Jawad, Adnan K.
Dawood, Alaa M.
Hakim S., Ahmed
Powiązania:
https://bibliotekanauki.pl/articles/35540380.pdf
Data publikacji:
2021
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
corrugated sheets
shear transfer
shear span
slip
deflection
Opis:
Profile deck steel sheets are used in composite deck slabs. These sheets are standard in dimensions and shapes besides they are supplied with embossments and indentations. Such sheets are not available in Iraqi markets nowadays therefore people used another type of sheets which are corrugated without embossments or indentations in very wide range. This study covers the use of such sheets in composite slabs as decks instead of standard profiled steel sheets. The study comprises testing slabs of dimensions 0.9 × 2.5 m reinforced by steel fabric mesh and rested on corrugated sheets. Two types of shear spans are selected shorter and longer to study the longitudinal shear force transmitted due to the applied loads according to the Eurocode 4. The shorter shear spans are 600, 500 and 400 mm while longer one is 800, 750 and 700 mm. The study extended to support the requirements of design equation of the Eurocode by shear bond method also known as m–k method. The evaluated values of m and k are 0.094 and 65 respectively. The result of k which plays a very important role in shear transfer is small compared to what available in literature, therefore it is recommended to make use of shear connectors in such construction or any else method.
Źródło:
Scientific Review Engineering and Environmental Sciences; 2021, 30, 3; 411-423
1732-9353
Pojawia się w:
Scientific Review Engineering and Environmental Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
FEM modelling of the static behaviour of reinforced concrete beams considering the nonlinear behaviour of the concrete
Autorzy:
Pazdan, Maciej
Powiązania:
https://bibliotekanauki.pl/articles/1845144.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
concrete
reinforced concrete
deflection
numerical analysis
Young's modulus
Opis:
This paper presents a finite element (FE) method of modelling reinforced concrete beams. The proposed model takes into account the phenomena characteristic of reinforced concrete structures, such as the interaction between two materials (concrete and steel), the cracking caused by mechanical loads and the variation of the Young's modulus under increasing load. A relevant numerical FE analysis was carried out in the ABAQUS system using the concrete damaged plasticity (CDP) model. The character of Young's modulus variation due to increasing stress intensity level was taken from the author’s own research. The results of the FE calculations were compared with the results yielded by the author's numerical bar model.
Źródło:
Studia Geotechnica et Mechanica; 2021, 43, 3; 206-223
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of artificial neural networks to predict the deflections of reinforced concrete beams
Autorzy:
Kaczmarek, M.
Szymańska, A.
Powiązania:
https://bibliotekanauki.pl/articles/178826.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
reinforced concrete beams
research
deflection
artificial neural network
Opis:
Nonlinear structural mechanics should be taken into account in the practical design of reinforced concrete structures. Cracking is one of the major sources of nonlinearity. Description of deflection of reinforced concrete elements is a computational problem, mainly because of the difficulties in modelling the nonlinear stress-strain relationship of concrete and steel. In design practise, in accordance with technical rules (e.g., Eurocode 2), a simplified approach for reinforced concrete is used, but the results of simplified calculations differ from the results of experimental studies. Artificial neural network is a versatile modelling tool capable of making predictions of values that are difficult to obtain in numerical analysis. This paper describes the creation and operation of a neural network for making predictions of deflections of reinforced concrete beams at different load levels. In order to obtain a database of results, that is necessary for training and testing the neural network, a research on measurement of deflections in reinforced concrete beams was conducted by the authors in the Certified Research Laboratory of the Building Engineering Institute at Wrocław University of Science and Technology. The use of artificial neural networks is an innovation and an alternative to traditional methods of solving the problem of calculating the deflections of reinforced concrete elements. The results show the effectiveness of using artificial neural network for predicting the deflection of reinforced concrete beams, compared with the results of calculations conducted in accordance with Eurocode 2. The neural network model presented in this paper can acquire new data and be used for further analysis, with availability of more research results.
Źródło:
Studia Geotechnica et Mechanica; 2016, 38, 2; 37-46
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bending analysis of plates by superposing cylindrical deflections
Autorzy:
Jemielita, G. E.
Powiązania:
https://bibliotekanauki.pl/articles/281375.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
plate
reference solution
cylindrical deflection
superposing
Fourier series
Opis:
In this paper, the present exact solutions in the plate theory using the cylindrical deflection method and represented by the Fourier series corresponding to the oblique or Cartesian coordinates are given for a hingely supported triangular plate subject to a distributed load in form of a hexagonal pyramid and for a rectangular hingely supported plate subject to loading in form of a truncated octagonal pyramid. In the case of the rectangular hingely supported plate under the truncated octagonal pyramid load, a series of parametric solutions has been obtained. The solutions depend on the parameter ε. For various values of the parameter ε, various load cases are found.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 1; 95-105
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania czujników ugięć szyn oraz całkowanie sygnału z czujnika przyspieszeń pionowych szyn
Laboratory testing of rail deflection sensors and research into possibility of obtaining displacements from vertical rail acceleration time histories
Autorzy:
Sołkowski, J.
Górszczyk, J.
Kudła, D.
Powiązania:
https://bibliotekanauki.pl/articles/252635.pdf
Data publikacji:
2016
Wydawca:
Instytut Naukowo-Wydawniczy TTS
Tematy:
szyna
ugięcie
badanie
czujnik
splint
deflection
study
sensor
Opis:
W artykule przedstawiony został problem dokładności pomiarów przemieszczenia w laboratoryjnych badaniach dynamicznych z użyciem różnych typów czujników. Przeanalizowano trzy typy czujników mierzących ugięcie szyny, czujnik laserowy, magneto-indukcyjny oraz wiroprądowy. Wyniki uzyskane za pomocą poszczególnych czujników porównywano miedzy sobą oraz z wzorcowym wymuszeniem kinematycznym zrealizowanym za pomocą serwohydraulicznej maszyny wytrzymałościowej. Ponadto przedstawiono wynik całkowania rzeczywistego sygnału przyspieszeń szyny w celu uzyskania wykresów ugięć. Wyniki przedstawiono w postaci wykresów i tabel. Stwierdzono, że najlepszą zgodność z sygnałem generowanym przez maszynę wytrzymałościową uzyskał czujnik magneto indukcyjny. W zakresie całowania sygnału przyspieszeń pionowych szyny w celu uzyskania ugięć szyny stwierdzono możliwość stworzenia odpowiedniej metody pomiarowej. Jednakże na obecnym etapie nie może być ona jeszcze zastosowana jako rutynowa metoda pomiarowa, gdyż jej skuteczność wynosi ok. 20%. Autorzy pracują nad jej udoskonaleniem.
In the paper the problem of accuracy of rail displacement sensors is discussed. The sensors were tested in laboratory conditions using a hydraulic press as the template for cinematically enforced displacement. The measured displacements (up to 30Hz) were compared with one another and the most promising sensor was chosen. In the next step of the investigations, a field research was carried out in order to verify the practicality of the selected sensor (that was magnetic induction sensor). Moreover, an attempt was made to obtain a reliable rail displacement signal by double integration of the vertical rail acceleration. At the moment, however, the efficiency of the proposed method is at a level of 20%, which is not sufficient for practical routine procedures. The authors continue to work in order to refine the method and implement it into railway practice.
Źródło:
TTS Technika Transportu Szynowego; 2016, 12; 205-215
1232-3829
2543-5728
Pojawia się w:
TTS Technika Transportu Szynowego
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ wzmocnienia nawierzchni siatką z włókna szklanego na wybrane wskaźniki krzywej ugięć nawierzchni
The influence of the glass fiber mesh reinforcement on the selected pavement deflection curve indicators
Autorzy:
Kałuża, Mateusz
Kotasiński, Mirosław
Bzówka, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/24024747.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Inżynierów i Techników Komunikacji Rzeczpospolitej Polskiej
Tematy:
siatka z włókna szklanego
wskaźniki krzywizny
czasza ugięć
ugięciomierz FWD
glass fiber mesh
deflection indicators
deflection bowl
falling weight deflectometer (FWD)
Opis:
Przedmiotem artykułu jest analiza skuteczności wzmocnienia nawierzchni siatką z włókna szklanego zabudowaną w spodzie warstw z betonu asfaltowego. Przeprowadzono badania ugięciomierzem FWD, a następnie wyznaczono wybrane wskaźniki krzywizny czaszy ugięć. Wyniki zestawiono dla pomiaru z 2019 r. oraz kontrolnego z 2021 r., oceniono stan poszczególnych warstw konstrukcji nawierzchni wraz ze wskazaniem wpływu wzmocnienia na wartości jednego ze wskaźników. Potwierdzono korzystny wpływ wzmocnienia na stan wierzchnich warstw bitumicznych, zaś wpływ wzmocnienia na stan pozostałych stref nawierzchni określono jako nieznaczny.
The main subject of this paper is to investigate the effectiveness of applied glass fiber mesh as the reinforcement under asphalt concrete layers. The falling weight deflectometer (FWD) was used to determine the bowl of deflection indicators. The results of the primary measure from 2019 were compared with an additional control measure from 2021. The technical condition of pavement layers was evaluated together with the influence of the applied reinforcement. The positive effect of glass fiber mesh on a surface asphalt layer was confirmed. However, its impact on the other layers was minimal.
Źródło:
Drogownictwo; 2022, 5; 135--140
0012-6357
Pojawia się w:
Drogownictwo
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three models of a sandwich beam: bending, buckling, and free vibrations
Autorzy:
Magnucki, Krzysztof
Magnucka-Blandzi, Ewa
Wittenbeck, Leszek
Powiązania:
https://bibliotekanauki.pl/articles/38884025.pdf
Data publikacji:
2022
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
shear deformation theory
deflection; critical load
fundamental natural frequency
Opis:
This paper is devoted to the analytical modelling of a sandwich beam. Three models of this beam are elaborated. Two nonlinear individual shear theories of deformation of a plane cross-sections are proposed. Based on Hamilton’s principle, two differential equations of motion for each model are obtained. The bending, buckling and free flexural vibration problems of the simply-supported sandwich beam considering these three models are studied. The results of these analytical investigations are presented in tables.
Źródło:
Engineering Transactions; 2022, 70, 2; 97-122
0867-888X
Pojawia się w:
Engineering Transactions
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 165

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