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Bibliography by Ioan Sebesan

Books by Ioan Sebesan

Romanian Academy, 2020

Achieving dynamic performances within the parameters imposed by a safe traffic and by the running... more Achieving dynamic performances within the parameters imposed by a safe traffic and by the running speed increase is an essential part in the railway vehicles construction.
The general characteristics of the conventional wheel-rail system, of the constructive and geometric parts of the railway and of the mounted axles are presented in this book, together with the problems deriving from speed increase. The work also deals with the geometry of both the wheel-rail contact and the curve inscribing vehicles.
There are also presented problems connected with mounted axles kinematics, wheel-rail contact forces, external forces acting over the axle, safety against running off the rails and torsional capacity of vehicles.
An analysis of the quasi-stationary and dynamic leading forces of the vehicles is made together with the methods of establishing the position for inscribing vehicles in curves and the leading forces for different types of rolling devices are discussed.
Specific vibrations matters of the railway vehicles are taken into consideration, emphasizing on the hunting movement (which is analyzed on a wheel-rail contact phenomena basis). Modern technologies with elastic led axles and conjugated axles technologies are especially studied.
The stick-slip phenomenon of the railway motor vehicles is also analyzed.
Considering the problems involved in high-speed railway transportation, the author points out the technical parameters required for high-speed vehicles.

Papers by Ioan Sebesan

Mechanics Transport Communications - Academic journal,, 2008

Applied Mechanics and Materials, Nov 1, 2015

The track vertical irregularities are the originator of the vertical vibrations in the wheelset. ... more The track vertical irregularities are the originator of the vertical vibrations in the wheelset. These vibrations are further conveyed to the suspended masses of the vehicle, thus generating and maintaining their vibrations. The study of the vibrations behavior of the wheelset plays an important role in the research dealing with the improvement of the vehicle dynamic performance, mainly at high velocities. This paper examines the vibrations behavior of the wheelset during running at speed of up to 200 km/h on a track with stochastic vertical irregularities, which are mathematically represented via the power spectral density. As underlain on numerical simulations, a series of basic features of the wheelset vertical vibrations will stand out, in correlation with the velocity, track quality and its damping. The observations herein prove that the maximum level of vibrations is visible at the frequency resonance of the wheelset on the track. Similarly, it is evident that the wheelset vibrations behavior increases during the running at high velocities on a track with weak damping and low quality.

MATEC web of conferences, 2018

Mathematical Modelling in Civil Engineering, Mar 1, 2015

MATEC web of conferences, 2018

Applied Mechanics and Materials, Nov 1, 2015

Through the past years numerous theories regarding the contact between the wheel and the railway ... more Through the past years numerous theories regarding the contact between the wheel and the railway have been created with the purpose of resolving the interaction issues and improving the dynamical performances of the vehicle. In this context the paper comes with a three-dimensional approach of the contact between the wheel and the railway when there is a load transfer or a dual-contact. The analysis is done through the use of the CONTACT software which assimilates the contact the contact area through half-spaces and it divides it through the method the finite element [1]. In the contact area the linear elasticity theory is respected. CONTACT establishes the shape and size of the contact area between two elastically, deformable bodies found in tangential contact (normal loads). This thing is possible only if the form of the profiles found within the contact area is known. The analysis suggested through the paper validates the applicability of the CONTACT software for the profiles used by CFR and for the analysis of the dual-contact. Also, this approach allows the possibility for a tribological evaluation of the vehicle's behavior while traveling on a rail with excess as well with a rail with super-elevation deficiency.

Applied Mechanics and Materials, Nov 1, 2015

Power supply the energy needed for locomotives and electric trains is performed by means of panto... more Power supply the energy needed for locomotives and electric trains is performed by means of pantographs on the bodywork. These high performance producing vehicles in so far as the contact between the collector (pantograph) and the catenary (contact line) is achieved and maintained regardless of speed. Thanks to the constructive type of the pantograph and the location of the contact force varies in relation to speed and can give rise to phenomena of oscillators that enhances the vertical movements of the wire feeder. As such the problem is essential for a good current collection is dynamic in nature. The most favorable way of current collection is achieved when between full and contact wire can maintain contact through a permanent and constant contact, a situation difficult to achieve in practice because of the first bump of the contact line. Juddering movements in vehicle while walking to a modification of the contact pressure which, however, it was found that is negligible in relation to the wave-like movements of the contact line. This article has looked at what is the dynamic contact force variation where the pantograph is located on the body of the locomotive EP3 LE 060 EA of 5100 kW. For this I started from the constructive characteristics of the components of the pantograph.

The paper examines the differences between the torque in the centre casting of the railway vehicl... more The paper examines the differences between the torque in the centre casting of the railway vehicles in the curve running. The purpose of this study is to establish the influence of a lubricated plane centre casting, respectively non lubricated, on the report Y/Q (the safety value against the derailment).

This study addresses the issue of vehicle-track interaction dynamic effects, in horizontal-transv... more This study addresses the issue of vehicle-track interaction dynamic effects, in horizontal-transversal direction related to traffic, in a curve where there may be a curvature discontinuity. This situation leads to the emergence of significant transverse forces (attack shock) that may even cause the derailment of the vehicle. The paper presents a mathematical and mechanical model for the study of the "attack shock". The associated formulas have been particularized for the case of a tank wagon. The influences of the track unevennesses, the constructive factors and the impact of the vehicle on the dynamic force, are highlighted. The considered mechanical model has been validated through test data..

a free-access multidisciplinary publication of the Faculty of Engineering Hunedoara 1. Abstract: ... more a free-access multidisciplinary publication of the Faculty of Engineering Hunedoara 1. Abstract: The evaluation of running behavior for a railway vehicle is usually made on a testing railway center by direct determining the evaluation values, for instance accelerations or forces. These values are used in assessing the interaction between vehicle and track and mainly describe the wheel/rail system or are closely related to it. The running behavior of an electric multiple unit 1720 kW was studied on a rail sector in alignment, the vehicle being subject of minimum load conditions-namely without passengers, by analyzing the transverse and vertical accelerations that occur both in the bogie frame and car body of the vehicle.

MATEC Web of Conferences, 2018

In the case of urban rail transport, light vehicles can be an effective solution due to the advan... more In the case of urban rail transport, light vehicles can be an effective solution due to the advantages offered by the elastic wheels. One of the great advantages of these rolling elements is given by the reduction of unsuspended masses of the vehicle which have the effect of reducing the vehicle-rolling interaction forces. However, there are no other advantages to be missed, such as noise reduction (very important for urban vehicles) and improved walking quality. This paper aims at presenting the construction and design elements of the elastic wheels. It is hoped to improve the quality of the urban transport vehicles in Romania. At the same time, dynamic effects will be analysed and presented on the wheel - rail contact, in the case of vehicles equipped with elastic wheels.

The paper presents the calculation of the forces that occur on the buffing gear and draw gear dur... more The paper presents the calculation of the forces that occur on the buffing gear and draw gear during running on the curves depending on the tightening of the screw coupling. The choice of the buffing gear and draw gear for railway vehicles is done according to the provision from UIC leaflet no. 527-1 and 527-2, respectively to the report of the Commission of experts ORE B36/RP32.

In this paper the authors propose the validation of a new mathematical model used for the evaluat... more In this paper the authors propose the validation of a new mathematical model used for the evaluation of the longitudinal dynamic forces which appear on the traction, buffer and fastening devices during passenger trains braking. The following two cases are considered: a vehicle bound by a fixed system and launched on it at various initial speeds and the model of a train composed of two cars, braking at maximum circulation speed. The results are evaluated through the values of the forces and displacement of the buffers and the traction hook; also the results are correlated to those presented in the scientific literature.

Most of the studies performed up to the present time, refer to safety running of rolling stock de... more Most of the studies performed up to the present time, refer to safety running of rolling stock designed for passengers and freight trains, in standard operating conditions, under a strict schedule. This rolling stock usually runs with high speed, the risk of appearing running safety disorders increasing when the speed increases. Road-rail machines are designed for planned or unplanned maintenance interventions over railway infrastructure. These interventions are always made when the traffic is closed. Generally, road-rail machines are running at low speed. However, running safety disorders still could occur. The aim of the present study is to experimentally establish a method of static determination of the safety against overturning of road-rail machines, based on the analysis of the load distribution on the wheel in rail configuration of roadrail machines. Thus, an important factor in order to ensure road-rail machines safety against overturning is to ensure the load per wheels in ...

IOP Conference Series: Materials Science and Engineering, 2018

Romanian Academy, 2020

Achieving dynamic performances within the parameters imposed by a safe traffic and by the running... more Achieving dynamic performances within the parameters imposed by a safe traffic and by the running speed increase is an essential part in the railway vehicles construction.
The general characteristics of the conventional wheel-rail system, of the constructive and geometric parts of the railway and of the mounted axles are presented in this book, together with the problems deriving from speed increase. The work also deals with the geometry of both the wheel-rail contact and the curve inscribing vehicles.
There are also presented problems connected with mounted axles kinematics, wheel-rail contact forces, external forces acting over the axle, safety against running off the rails and torsional capacity of vehicles.
An analysis of the quasi-stationary and dynamic leading forces of the vehicles is made together with the methods of establishing the position for inscribing vehicles in curves and the leading forces for different types of rolling devices are discussed.
Specific vibrations matters of the railway vehicles are taken into consideration, emphasizing on the hunting movement (which is analyzed on a wheel-rail contact phenomena basis). Modern technologies with elastic led axles and conjugated axles technologies are especially studied.
The stick-slip phenomenon of the railway motor vehicles is also analyzed.
Considering the problems involved in high-speed railway transportation, the author points out the technical parameters required for high-speed vehicles.

Mechanics Transport Communications - Academic journal,, 2008

Applied Mechanics and Materials, Nov 1, 2015

The track vertical irregularities are the originator of the vertical vibrations in the wheelset. ... more The track vertical irregularities are the originator of the vertical vibrations in the wheelset. These vibrations are further conveyed to the suspended masses of the vehicle, thus generating and maintaining their vibrations. The study of the vibrations behavior of the wheelset plays an important role in the research dealing with the improvement of the vehicle dynamic performance, mainly at high velocities. This paper examines the vibrations behavior of the wheelset during running at speed of up to 200 km/h on a track with stochastic vertical irregularities, which are mathematically represented via the power spectral density. As underlain on numerical simulations, a series of basic features of the wheelset vertical vibrations will stand out, in correlation with the velocity, track quality and its damping. The observations herein prove that the maximum level of vibrations is visible at the frequency resonance of the wheelset on the track. Similarly, it is evident that the wheelset vibrations behavior increases during the running at high velocities on a track with weak damping and low quality.

MATEC web of conferences, 2018

Mathematical Modelling in Civil Engineering, Mar 1, 2015

MATEC web of conferences, 2018

Applied Mechanics and Materials, Nov 1, 2015

Through the past years numerous theories regarding the contact between the wheel and the railway ... more Through the past years numerous theories regarding the contact between the wheel and the railway have been created with the purpose of resolving the interaction issues and improving the dynamical performances of the vehicle. In this context the paper comes with a three-dimensional approach of the contact between the wheel and the railway when there is a load transfer or a dual-contact. The analysis is done through the use of the CONTACT software which assimilates the contact the contact area through half-spaces and it divides it through the method the finite element [1]. In the contact area the linear elasticity theory is respected. CONTACT establishes the shape and size of the contact area between two elastically, deformable bodies found in tangential contact (normal loads). This thing is possible only if the form of the profiles found within the contact area is known. The analysis suggested through the paper validates the applicability of the CONTACT software for the profiles used by CFR and for the analysis of the dual-contact. Also, this approach allows the possibility for a tribological evaluation of the vehicle's behavior while traveling on a rail with excess as well with a rail with super-elevation deficiency.

Applied Mechanics and Materials, Nov 1, 2015

Power supply the energy needed for locomotives and electric trains is performed by means of panto... more Power supply the energy needed for locomotives and electric trains is performed by means of pantographs on the bodywork. These high performance producing vehicles in so far as the contact between the collector (pantograph) and the catenary (contact line) is achieved and maintained regardless of speed. Thanks to the constructive type of the pantograph and the location of the contact force varies in relation to speed and can give rise to phenomena of oscillators that enhances the vertical movements of the wire feeder. As such the problem is essential for a good current collection is dynamic in nature. The most favorable way of current collection is achieved when between full and contact wire can maintain contact through a permanent and constant contact, a situation difficult to achieve in practice because of the first bump of the contact line. Juddering movements in vehicle while walking to a modification of the contact pressure which, however, it was found that is negligible in relation to the wave-like movements of the contact line. This article has looked at what is the dynamic contact force variation where the pantograph is located on the body of the locomotive EP3 LE 060 EA of 5100 kW. For this I started from the constructive characteristics of the components of the pantograph.

The paper examines the differences between the torque in the centre casting of the railway vehicl... more The paper examines the differences between the torque in the centre casting of the railway vehicles in the curve running. The purpose of this study is to establish the influence of a lubricated plane centre casting, respectively non lubricated, on the report Y/Q (the safety value against the derailment).

This study addresses the issue of vehicle-track interaction dynamic effects, in horizontal-transv... more This study addresses the issue of vehicle-track interaction dynamic effects, in horizontal-transversal direction related to traffic, in a curve where there may be a curvature discontinuity. This situation leads to the emergence of significant transverse forces (attack shock) that may even cause the derailment of the vehicle. The paper presents a mathematical and mechanical model for the study of the "attack shock". The associated formulas have been particularized for the case of a tank wagon. The influences of the track unevennesses, the constructive factors and the impact of the vehicle on the dynamic force, are highlighted. The considered mechanical model has been validated through test data..

a free-access multidisciplinary publication of the Faculty of Engineering Hunedoara 1. Abstract: ... more a free-access multidisciplinary publication of the Faculty of Engineering Hunedoara 1. Abstract: The evaluation of running behavior for a railway vehicle is usually made on a testing railway center by direct determining the evaluation values, for instance accelerations or forces. These values are used in assessing the interaction between vehicle and track and mainly describe the wheel/rail system or are closely related to it. The running behavior of an electric multiple unit 1720 kW was studied on a rail sector in alignment, the vehicle being subject of minimum load conditions-namely without passengers, by analyzing the transverse and vertical accelerations that occur both in the bogie frame and car body of the vehicle.

MATEC Web of Conferences, 2018

In the case of urban rail transport, light vehicles can be an effective solution due to the advan... more In the case of urban rail transport, light vehicles can be an effective solution due to the advantages offered by the elastic wheels. One of the great advantages of these rolling elements is given by the reduction of unsuspended masses of the vehicle which have the effect of reducing the vehicle-rolling interaction forces. However, there are no other advantages to be missed, such as noise reduction (very important for urban vehicles) and improved walking quality. This paper aims at presenting the construction and design elements of the elastic wheels. It is hoped to improve the quality of the urban transport vehicles in Romania. At the same time, dynamic effects will be analysed and presented on the wheel - rail contact, in the case of vehicles equipped with elastic wheels.

The paper presents the calculation of the forces that occur on the buffing gear and draw gear dur... more The paper presents the calculation of the forces that occur on the buffing gear and draw gear during running on the curves depending on the tightening of the screw coupling. The choice of the buffing gear and draw gear for railway vehicles is done according to the provision from UIC leaflet no. 527-1 and 527-2, respectively to the report of the Commission of experts ORE B36/RP32.

In this paper the authors propose the validation of a new mathematical model used for the evaluat... more In this paper the authors propose the validation of a new mathematical model used for the evaluation of the longitudinal dynamic forces which appear on the traction, buffer and fastening devices during passenger trains braking. The following two cases are considered: a vehicle bound by a fixed system and launched on it at various initial speeds and the model of a train composed of two cars, braking at maximum circulation speed. The results are evaluated through the values of the forces and displacement of the buffers and the traction hook; also the results are correlated to those presented in the scientific literature.

Most of the studies performed up to the present time, refer to safety running of rolling stock de... more Most of the studies performed up to the present time, refer to safety running of rolling stock designed for passengers and freight trains, in standard operating conditions, under a strict schedule. This rolling stock usually runs with high speed, the risk of appearing running safety disorders increasing when the speed increases. Road-rail machines are designed for planned or unplanned maintenance interventions over railway infrastructure. These interventions are always made when the traffic is closed. Generally, road-rail machines are running at low speed. However, running safety disorders still could occur. The aim of the present study is to experimentally establish a method of static determination of the safety against overturning of road-rail machines, based on the analysis of the load distribution on the wheel in rail configuration of roadrail machines. Thus, an important factor in order to ensure road-rail machines safety against overturning is to ensure the load per wheels in ...

IOP Conference Series: Materials Science and Engineering, 2018

IOP Conference Series: Materials Science and Engineering, 2019

In the paper is presented some theoretical considerations underlying the use of these springs in ... more In the paper is presented some theoretical considerations underlying the use of these springs in the railway vehicle constructions. The use of these springs as elastic suspension systems is justified by a few advantages that they offer in service, such as: simplicity, weight and low gauge, do not require guides, work without wear and have a high reliability. The elasticity in the three-principal: vertical, horizontal-transverse and longitudinal directions recommends the use of these springs in the axle’s suspension of the vehicle. As an application it is presented the axle suspension dimensioning elements in the case of a carload subway vehicle.

IOP Conference Series: Materials Science and Engineering, 2019