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1

Measurement and analysis of the performance of the PVP-20 slip detection device

Hełka Andrzej, Wall Michał

Zeszyty Naukowe. Transport / Politechnika Śląska

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2023

|

z. 118

93--108

EN

One of the most critical elements ensuring the proper operation of locomotives are devices that detect and eliminate slipping, especially during the start-up of the locomotive in difficult operating conditions. Various types of slip control systems and methods are used on traction vehicles, depending on the design of a given locomotive and the assumptions made related to the functionality of a given solution. This article describes the PVP-20 type slip detection device used in many older electric locomotives. A proprietary measuring system was developed, enabling it to be connected to the locomotive circuit, to perform measurements in conditions of large disturbances and high voltages prevailing on the electric locomotive. Using this measuring system, the PVP-20 device was tested under operating conditions for the ability to detect slips. It has been shown that the described device is highly insensitive. Hence, we propose our concept for solving this problem.

2

Footwear safety in the light of scientific research

Przepiórka Jacek, Szczerek Marian

Tribologia

|

2023

|

nr 4

65--77

EN

Improving living conditions and developing medical care contributes to increasing human life expectancy. Because motor skills decrease with age, older people need comfortable shoes that provide a high level of safety. The soles should not deform during temperature changes, they should have appropriate thermal insulation properties and a good grip to dry, wet, and dirty floor surfaces, as slips usually occur on surfaces covered with ice, water, oil, grease, mud, etc. During the use of footwear, the friction coefficient is important. It depends on various factors, including: the type of a polymer matrix, auxiliary agents, the shape of the tread, the hardness of the sole, stiffness, wettability, and pressure. From the point of view of the footwear safety, the type of the sole material, its construction, especially the profile of the sole, the shape of the heel, and the thickness of the sole, as well as the method of use, are important. The types of rubbing surfaces (their structures, physical properties), the temperature of the contacting bodies, and the type of the substrate have a significant impact on friction. The assumption and purpose of the article was to compare the methods for determining the coefficient of friction between the shoe soles and walking surfaces used in scientific research around the world in relation to the methodology developed in Poland.

PL

Poprawa warunków życia oraz rozwój opieki medycznej przyczyniają się do zwiększenia długości życia człowieka. Ponieważ sprawność motoryczna zmniejsza się wraz z długością życia, osoby w wieku dojrzałym potrzebują obuwia wygodnego i zapewniającego wysoki poziom bezpieczeństwa. Podeszwy nie powinny odkształcać się przy zmianach temperatury, powinny wykazywać odpowiednie właściwości termoizolacyjne oraz odporność na poślizg zarówno w warunkach suchych, jak i na powierzchniach mokrych i zabrudzonych. Poślizg obuwia występuje zwykle na podłożach oblodzonych, zwilżonych wodą, olejami, smarami, błotem itp. Podczas użytkowania spodów obuwia istotne znaczenie ma współczynnik tarcia, który zależy od wielu czynników między innymi od: rodzaju matrycy polimerowej, środków pomocniczych, kształtu bieżnika, twardości spodu, sztywności, zwilżalności oraz nacisku. Z punktu widzenia bezpieczeństwa użytkowania obuwia istotne znaczenie ma rodzaj materiału spodu, jego konstrukcja, a szczególnie profil podeszwy, kształt obcasa i grubość podeszwy, a także sposób użytkowania. Znaczny wpływ na tarcie wywierają rodzaje trących powierzchni (ich struktura, właściwości fizyczne), temperatura oraz rodzaj podłoża. Założeniem i celem artykułu było porównania metod określania współczynnika tarcia pomiędzy spodem obuwia a podłożem stosowanych w badaniach naukowych na świecie w odniesieniu do metodyki opracowanej w Polsce.

3

Charakterystyka przyczepności prętów GFRP i BFRP do betonu z dodatkiem zeolitu i metakaolinitu

Urbański Marek, Woyciechowski Piotr, Szmigiera Elżbieta, Adamczewski Grzegorz, Sosnowska Edyta

Przegląd Budowlany

|

2023

|

R. 94, nr 11-12

121--127

PL

Porównano zależności przyczepność-poślizg oraz mechanizmy zniszczenia dla betonu z dodatkami zeolitu i metakaolinitu w obecności prętów GFRP, BFRP i stalowych. Przyczepność prętów GFRP do betonu z dodatkiem metakaolinitu była o 50% większa niż do betonu zwykłego, natomiast przyczepność do betonu z zeolitem podobna. W przypadku prętów BFRP stwierdzono wzrost przyczepności o 7% dla betonu z metakaolinitem. Pręty BFRP miały większą przyczepność w stosunku do zbrojenia stalowego. Zmiana przyczepności prętów GFRP i BFRP była stopniowa, a poślizg był kilkukrotnie większy niż prętów stalowych.

EN

Bond stress-slip relationship and failure mechanisms for concrete with additions of zeolite and metakaolin in the presence of GFRP, BFRP and steel bars were compared. The bond strength of GFRP bars to concrete with the addition of metakaolin was 50% higher than to ordinary concrete, while the bond strength to concrete with zeolite was similar. In the case of BFRP bars, an increase in bond strength by 7% was found for concrete with metakaolin. BFRP bars had greater bond strength to steel reinforcement. The change in the bond stress of the GFRP and BFRP bars was gradual and the slip was several times greater than that of the steel bars.

4

Hamulce w pojazdach szynowych. Podstawowa charakterystyka, budowa i eksploatacja

Górowski Maciej

Paragraf na Drodze

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2023

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Nr 2

17--49

PL

Celem artykułu jest przybliżenie tematyki związanej z budową i zasadami działania układów hamulcowych stosowanych w pojazdach szynowych – kolejowych i tramwajowych, ze zwróceniem uwagi na aspekty dotyczące bezpieczeństwa, osiągania odpowiedniej skuteczności hamowania i przyczepności pomiędzy kołem a szyną. Artykuł jest wstępem teoretycznym z zakresu stosowanych rozwiązań i wymagań stawianym układom hamulcowym i układom wspomagającym działanie hamulców w pojazdach szynowych.

EN

The aim of the article is to present the issues related to the construction and principles of operation of braking systems used in railroad and tramway vehicles, paying attention to aspects of safety, achieving appropriate braking performance and wheel to rail adhesion. The article is a theoretical introduction to the applied solutions and requirements for braking systems in rail vehicles together with systems supporting the operation of brakes.

5

Experimental and numerical evaluations of the bond behaviour between ribbed steel rebars and concrete

Biscala Hugo C.

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e159, 2023

EN

The study of interfacial behaviour between ribbed steel rebars and concrete is a subject that has been widely studied. However, the definition of the bond stress distribution throughout the embedded length of the steel rebar is still controversial due to the difficulty of experimentally obtaining such distribution for a fixed load magnitude. It is also undeniable its relevancy for the better understanding and model reinforced concrete (RC) structures. So, the definition of the local behaviour between the ribbed steel rebar and concrete is critical to correctly simulate the adherence between both materials. In this matter, the local bond-slip models recommended in codes seem to satisfy some researchers while others suggest prudence in using them. Therefore, only choosing the correct bond-slip relationship may lead to exact interpretations and conclusions of the structural behaviour of a concrete structure but with the existing different bond-slip types, researchers can be misled inadvertently. This work aims to clarify some of these aspects by numerically simulating several pull-out tests under different conditions and checking their influence (or not) on real-scale specimens. After the validation of the numerical model through a proposed new bond-slip relationship, other parameters were studied also. Although the type of the bond-slip relationship influences the detachment of the steel rebar from the concrete, the yielding of the former material was found to be the main parameter that masks the differences in the behaviour of real-scale RC structures when different types of bond-slip relationships were considered in the numerical simulations.

6

Visco-elastic fluid model in an inclined porous stenosed artery with slip effect and body acceleration

Manisha Rana, Kumar Surendra

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 4

82--104

EN

The present paper analyzes an unsteady magnetohydrodynamic blood flow model of an visco-elastic fluid through an inclined porous stenosed artery with body acceleration and slip effect. Navier-Stokes equations have been used to describe the blood flow model. The governing equation of blood flow is solved by an analytic method by considering blood as an incompressible, visco-elastic fluid, and suspension of RBC’s in plasma. Axial velocity, blood acceleration, flow rate, and shear stress are derived numerically by using the finite Laplace and Hankel transformation and their inverse. The effect of parameters such as the visco-elasticity parameter, Womersley number, Hartmann number, inclination angle, parameter of slip, and body acceleration frequency is analyzed. Axial velocity reduces as the Hartmann number and visco-elasticity parameter enhance and it enhances with the enhancement of the slip parameter and inclination angle. The study is beneficial for finding the effect of slip parameter, porosity factor and Hartmann number when a human body is exposed to MRI and CT scan.

7

Experimental investigation of bonding behavior of anchoraged timber-to-timber joint

Ghoroubi Rahim, Mercimek Ömer, Sakin Shaimaa, Anil Özgür

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e7, 2022

EN

The comprehensive experimental study examining the general load–displacement behavior, stress distributions and shear stress–shear-displacement behaviors in the connection area when wood structural elements are combined with adhesive or adhesive with mechanical anchorages have been found in very limited number of studies in the literature. Therefore, an experimental study was planned. In this study, the general load–displacement behavior of the timber connection regions which are connected by adhesive and mechanical anchorages together with adhesive, with varying lengths of 180, 240 and 350 mm are investigated experimentally. Besides, the effect of changing the number and location of mechanical anchorages used in the connection area on the general load–displacement behavior and shear stress–shear-displacement behavior was also investigated. Using the load–displacement graphs obtained as a result of the experimental study, a generalized material model is proposed for the shear stress–shear-displacement interfacial adhesion surface for wood–wood junction points. This material model, which is proposed for wood–wood connection points with mechanical anchors, is a model that can be useful and can be used in the analysis of structural systems containing such connections using finite element software. It is thought that the overall capacity and load–displacement behavior of structural systems containing such connection points can be calculated more realistically using the proposed interfacial material model.

8

Sliding of spherical ball on solid lubricating coating combined with wear process

Białas Marcin, Maciejewski Jan, Kucharski Stanisław

Welding Technology Review

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2021

|

R. 93, nr 1

39--50

EN

In present paper we show results of ball-on-disk wear experiment of MoS2 film deposited on Ti6Al4V substrate. The ball material is aluminium oxide. The tests are performed for different surrounding temperature conditions: 20°C, 200°C and 350°C. It is shown that depth of the wear groove increases with increasing surrounding temperature. A finite element modelling approach is next developed to mimic the experimental observations of ball-on-disk wear process. It is based on the assumption of steady state condition developed during short time scale at contact region. The steady state results can next be applied to long time scale in which wear process is numerically simulated. Model results are compared with experimentally obtained wear groove and show satisfactory agreement.

PL

Artykuł prezentuje wyniki testu zużycia powłoki samosmarującej MoS2 nałożonej na podłoże wykonane z materiału Ti6AI4V. Powłoka obciążona jest kulką szafirową w ruchu rotacyjnym. Badania wykonano w trzech różnych temperaturach otoczenia: 20°C, 200°C oraz 350°C. Wykazano, że głębokość rowka zużyciowego wzrasta wraz ze wzrostem temperatury otoczenia. Zaproponowano model metody elementów skończonych za pomocą którego zasymulowany został proces zużycia warstwy. Punktem wyjścia dla tej części pracy było założenie stanu ustalonego, powstającego w obszarze kontaktu pomiędzy kulą a warstwą. Warunki odpowiadające temu stanowi przyjęto do matematycznego opisu procesu zużycia z wykorzystaniem równań Archarda. Na zakończenie eksperymentalny profil zużycia porównany został z wynikami otrzymanymi metodą elementów skończonych.

9

Exact solutions for fractionalized second grade fluid flows with boundary slip effects

Dehraj S., Malookani R. A., Aasoori S. K., Bhutto G. M., Arain L.

International Journal of Applied Mechanics and Engineering

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2021

|

Vol. 26, no. 1

88--103

EN

In this paper, an exact analytical solution for the motion of fractionalized second grade fluid flows moving over accelerating plate under the influence of slip has been obtained. A coupled system of partial differential equations representing the equation of motion has been re-written in terms of fractional derivatives form by using the Caputo fractional operator. The Discrete Laplace transform method has been employed for computing the expressions for the velocity field […] and the corresponding shear stress […]. The obtained solutions for the velocity field and the shear stress have been written in terms of Wright generalized hypergeometric function pqψ and are expressed as a sum of the slip contribution and the corresponding no-slip contribution. In addition, the solutions for a fractionalized, ordinary second grade fluid and Newtonian fluid in the absence of slip effect have also been obtained as special case. Finally, the effect of different physical parameters has been demonstrated through graphical illustrations.

10

Study of the two-rotor electric motor of a drive of vehicle drive wheels

Sergienko Nikolay, Kuznetsov Valeriy, Liubarskyi Borys, Pastushchina Mariia, Gołębiowski Piotr, Tkaczyk Sławomir

Archives of Transport

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2021

|

Vol. 60, iss. 4

245--257

EN

In recent years, electric and hybrid vehicles have taken more and more attention due to their apparent advantages in saving fuel resources and reducing harmful emissions into the environment. Even though electric vehicles can solve the ecological problem, their operation is faced with a number of inconveniences associated with a limited driving distance from a single charge due to limited storage of energy from an independent power source and a lack of the required service and repair infrastructure. In hybrid and electric vehicles one of the main parameters is the curb weight, which affects energy consumption, vehicle speed, stability, controllability and maneuverability. In this regard, leading car manufacturers use parts with a low specific weight (non-metallic, aluminum alloys, etc.) in the design and also exclude some units from the design. Due to these technical solutions, the vehicle's operating is improved. One of the groups of parameters to be defined when designing a new electric vehicle is the parameters relating to the electric motor. The purpose of the article is determination of the mechanical characteristics of a two-rotor electric motor during magnetic flux control and assessment of the possibility of organizing the drive of the drive wheels of the vehicle. The electric motor has two mechanically independent outputs. For the study, an electrical equivalent diagram has been developed for the given two-rotor electric motor. A simulation model of the equivalent diagram has been built. Simulating the interaction processes of the rotors with the stator made it possible to obtain data for building the mechanical characteristics for each output of the electric motor. Analysis and processing of the mechanical characteristics data of the electric motors showed the conformity and the range of changes in the torque on each of the rotors when changing their slip and revolution, which are required when building algorithms for the operation of electric motor control systems as part of drives for various purposes. Analysis of the simulation results made it possible to assess the possibility of using the considered two-rotor electric motor for the drive of drive wheels in an electric and hybrid wheeled vehicle.

11

Jak obiektywnie ocenić odporność posadzki na poślizg?

Sudoł Ewa

Inżynier Budownictwa

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2020

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nr 10

58--62

12

Influence of heat generation/absorption on mixed convection flow behaviour in the presence of Lorentz forces in a vertical micro circular duct having time periodic boundary conditions: steady periodic regime

Aina B., Isa S.

International Journal of Applied Mechanics and Engineering

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2020

|

Vol. 25, no. 4

1--21

EN

The problem of mixed convection flow of a heat generating/absorbing fluid in the presence existence of Lorentz forces in a vertical micro circular subjected to a periodic sinusoidal temperature change at the surface has been studied taking the first-order slip and jump effects into consideration. The research analysis is carried out by considering a fully developed parallel flow and steady periodic regime. The governing equations, together with the constraint equations which arise from the definition of mean velocity and temperature, are written in a dimensionless form and mapped into equations in the complex domain. One obtains two independent boundary value problems, which provide the mean value and the oscillating term of the velocity and temperature distributions. These boundary value problems are solved analytically. A parametric study of some of the physical parameters involved in the problem is conducted. The results of this research revealed that the magnetic field has a damping impact on the flow and results in decreases in fluid velocity for both air and water. Furthermore, the presence of the heat generation parameter is seen to enhance the temperature distribution and this is reflected as an increase in the magnitude of the oscillation dimensionless velocity, whereas in the presence of heat absorption a reversed trend occurs.

13

Finite beam element with 22 DOF for curved composite box girders considering torsion, distortion, and biaxial slip

Zhu Li, Wang Jia-Ji, Li Ming-Jie, Chen Chao, Wang Guang-Ming

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 4

16--34

EN

Experimental and numerical study on the mechanical performance of curved steel–concrete composite box girders is reported in this research. First, this research establishes a theoretical model for curved composite girders with 11° of freedoms (DOFs) for each node. The DOFs include the longitudinal displacement, transverse displacement, deflection, torsion angle, warping angle, and interface biaxial slip between steel and concrete. Based on the virtual work theorem, the equilibrium function, the stiffness matrix, the node displacement matrix and the external load matrix are proposed for the curved composite girders using the FE spatial discretization. Second, the authors conduct an experimental program on three large-scale curved composite girders with various interface shear connectors and central angles. The comparison between the developed finite beam element, the elaborate FE model and the test results indicates the developed finite beam element has an adequate level of accuracy in predicting the deflection, the torsion angle and the axial strain distribution of test specimens. Third, based on the developed finite beam element model, the effect of initial curvature, number of diaphragms, and the interface connector stiffness on the curved composite girder is examined. The simulation results showed that the initial curvature significantly contributes to the displacement and stress of composite girders. Applying more diaphragms can notably reduce the distortion angle and distortion displacement. The interface shear connector stiffness has a significant influence on the curved composite girder. With the increasing shear connector stiffness, the displacement and stress of curved composite girders decrease notably. Based on the parametric analyses, it is recommended to limit the central angle of simply supported composite girder below 45°, to apply an adequate number of diaphragms, and to design curved composite girders as fully shear connection specimens.

14

Evolution of Goss texture in an Al–Cu–Mg alloy during cold rolling

Zhao Qi, Liu Zhiyi, Hu Yangcheng, Li Shasha, Bai Song

Archives of Civil and Mechanical Engineering

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2020

|

Vol. 20, no. 1

340--354

EN

Evolution of Goss texture in an Al–Cu–Mg alloy during cold rolling was investigated by three-dimensional orientation distribution functions, electron back-scattered diffraction and transmission electron microscopy. The results showed that with increasing reduction from 23.7 to 80%, Goss textures gradually transformed into Brass texture through the activation of sole {111}<110> slip systems. When rolling reduction further increased from 80 to 86.3%, Goss texture rather than Brass started to rotate towards Copper and S components. The formation of Copper and S textures at these high reductions was attributed to the activation of {110}<110> and {001}<110> non-octahedral slip systems.

15

Unsteady three-dimensional MHD nanofluid flow over a stretching sheet with variable wall thickness and slip effects

Kumar G. Vinod, Varma S. V. K., Kumar R. V. M. S. S. K.

International Journal of Applied Mechanics and Engineering

|

2019

|

Vol. 24, no. 3

709--724

EN

The stretching sheets with variable thickness may occur in engineering applications more frequently than a flat sheet. Due to its various applications, in the present analysis we considered a three dimensional unsteady MHD nanofluid flow over a stretching sheet with a variable wall thickness in a porous medium. The effects of radiation, viscous dissipation and slip boundary conditions are considered. Buongiorno’s model is incorporated to study the combined effects of thermophoresis and Brownian motion. The dimensionless governing equations are solved by using MATLAB bvp4c package. The impact of various important flow parameters is presented and analysed through graphs and tables. It is interesting to note that all the three boundary layer thicknesses are diminished by slip parameters. Further, the unsteady parameter decreases the hydromagnetic boundary layer thickness.

16

Unsteady MHD thermal diffusive and radiative fluid flow past a vertical porous plate with chemical reaction in slip flow regime

Ravi Kumar D., Jayarami Reddy K., Raju M. C.

International Journal of Applied Mechanics and Engineering

|

2019

|

Vol. 24, no. 1

117--129

EN

An analytical solution of an MHD free convective thermal diffusive flow of a viscous, incompressible, electrically conducting and heat-absorbing fluid past a infinite vertical permeable porous plate in the presence of radiation and chemical reaction is presented. The flow is considered under the influence of a magnetic field applied normal to the flow. The plate is assumed to move with a constant velocity in the direction of fluid flow in slip flow regime, while free stream velocity is assumed to follow the exponentially increasing small perturbation law. The velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number distributions are derived and have shown through graphs and tables by using the simple perturbation technique.

17

Role of brownian motion and thermophoresis effects on hydromagnetic flow of nanofluid over a nonlinearly stretching sheet with slip effects and solar radiation

Anjali Devi S. P., Mekala S.

International Journal of Applied Mechanics and Engineering

|

2019

|

Vol. 24, no. 3

489--508

EN

Hydromagnetic flow of water based nanofluids over a nonlinearly stretching sheet in the presence of velocity slip, temperature jump, magnetic field, nonlinear thermal radiation, thermophoresis and Brownian motion has been studied. The article focuses on Cu water nanofluid and Ag water nanofluid. The similarity transformation technique is adopted to reduce the governing nonlinear partial differential equations into nonlinear ordinary differential equations and then they are solved numerically utilizing the Nachistem – Swigert shooting method along with the fourth order Runge Kutta integration technique. The influence of physical parameters on the flow, temperature and nanoparticle volume fraction are presented through graphs. Also the values of the skin friction coefficient at the wall and nondimensional rate of heat transfer are given in a tabular form. A comparative study with previous published results is also made.

18

Odporność na poślizg posadzek

Sudoł Ewa

Builder

|

2019

|

R.23, nr 2

44--47

19

Entropy generation on MHD slip flow over a stretching cylinder with heat generation/absorption

Jain S., Bohra S.

International Journal of Applied Mechanics and Engineering

|

2018

|

Vol. 23, no. 2

413--428

EN

In the present study, we have investigated entropy generation on a magnetohydrodynamic fluid flow and heat transfer over a stretching cylinder with a porous medium in slip flow regime. A uniform heat source and radiation is also considered. Similarity transformation has been applied for making an ordinary differential equation from nonlinear governing partial differential equations. The numerical solution for the set of nonlinear ordinary differential equations has been obtained by using the fourth-order Runge-Kutta scheme together with the shooting method. The effects of pertinent parameters such as the magnetic field parameter, permeability parameter, slip parameter, Prandtl number and radiation parameter on the fluid velocity distribution, temperature distribution, entropy generation and Bejan number are discussed graphically.

20

Beam bond tests of GFRP and steel reinforcement to concrete

Szczech D., Kotynia R.

Archives of Civil Engineering

|

2018

|

Vol. 64, nr 4/II

243--256

EN

The paper presents research program of bond between glass fiber reinforced polymer bars and concrete in reference to the steel bars. Bond between the reinforcement and concrete is a crucial parameter governing a behaviour of reinforced concrete members and transferring of the internal forces from concrete to the reinforcement. The use of FRP bars as an equivalent reinforcement to steel in concrete structures has increased in recent years. The FRP bars are very different from steel, mainly due to much lower elasticity modulus and their anisotropic structure. Good performance of FRP reinforced concrete requires sufficient interfacial bond between bars and concrete. However, there are no specific standards referring to the surface preparation of these bars, that leads to variable bond behaviour of the composite reinforcement to the concrete. The objective of the study was to investigate the influence of variable parameters on the bond behaviour to concrete. The experimental program consisted of eighteen beam bond specimens varying in: bar diameter (12mm, 16mm, 18mm) and type of reinforcement (GFRP sand – coated and steel bars). Although the GFRP bars indicated good bond behaviour to concrete, the average bond strength was slightly lower than that of steel reinforcement of 16mm and 18 mm, while it was higher for the GFRP bars of 12mm diameter.