Goran Radoičić - Academia.edu (original) (raw)
Papers by Goran Radoičić
The quality of the model used to describe a structure is the main value of the scientific selecti... more The quality of the model used to describe a structure is the main value of the scientific selection of technical analyses. This theoretical-experimental analysis shows the quality of modern dynamic modeling when it comes to modeling structures using linear members (1D finite elements). A tower crane structure is observed as a representative of large structures. A FEM structure model is created and subjected to testing of its static and dynamic properties. Elastic displacements and forms of model oscillations are searched for. Numerically obtained theoretical solutions are compared to experimental results. The quality of modern structure modeling application has a deviation of less than 2%. At the locations of the pronounced bending of the lattice, in the structure of the cantilever type, the elastic displacement deviation is less than 3%. The differences in the results of theoretical models and of experimental studies indicate the sensitivity of modeling quality depending on the experience of the authors and the restrictions of theoretical models in the description of connections in the truss node. The paper points to the elements of quality modeling, the scope of the number of applied structure elements, the redundant detailedness of some descriptions, the importance of the finite element type selection, the experimental values of vibration damping and the tower cranes properties. On the basis of these analyses, it is possible to develop analogue models which assure the quality-precision in modeling responsible structures.
Istraživanja i projektovanja za privredu, 2018
This paper presents the investigation of importancefor determining the dynamic structural respons... more This paper presents the investigation of importancefor determining the dynamic structural response of heavy lifting machines subjected to extreme external effects. A measuring system for the experimental investigation of the dynamics of heavy lifting machines is proposed.It shows the experimental testing results of carrying structures for several classes of hoisting and an export mining machine. The results refer to the most important dynamic parameters. The dynamic parameters also include the duration of transient phenomena in handling lifting structures and structural damping.A technical solution based on the measuring chain that is integrated into the mining export plant information system was developed in the research. The recommendation to choose optimal measuring equipment for this kind of measurement is given to manufacturers and users on the basis of the experience gained in the design and implementation of specifi c measuring systems. The technical specifi cation of amplifi ers and transducers that should be developed for this kind of measurement is also proposed.
This paper gives a contribution to solution of problem: "what kind of vehicles to choose?&qu... more This paper gives a contribution to solution of problem: "what kind of vehicles to choose?". The optimal choosing of vehicle is problem that is immanent in communal enterprises. The best technical solution isn't the most expensive usually, but it isn't and the cheapest. In the paper is presented the universal model for choosing of appropriate solution of vehicle for using in any business system. The model can be applied for the choosing of garbage collection truck. The model is based to multicriterial approach. According to given model, the choosing of vehicle contains five key activities. Process for the choosing of vehicle is presented step by step. This model includes transport requests and waste management system requests. The paper emphasizes importance of specific criteria resulting waste management system. In the paper are explained notion and split of special communal vehicles and garbage collection trucks especially. The paper insists to definition of special communal vehicles which use for special transport and which are equipped with necessary content for loading/unloading or other work function. In the paper is indicated to importance of costs, also and importance of organization and conception of maintenance for the procedure of choosing alternative vehicle. This paper indicates on necessary connecting of tree key factors: choosing of vehicle, quality maintaining and good logistics, in objective of implementation the best performances of transport system. .
IMK-14, 2016
U nedostatku eksperimentalnih analiza vibracija, mogu se uspešno vršiti numeričke analize nosećih... more U nedostatku eksperimentalnih analiza vibracija, mogu se uspešno vršiti numeričke analize nosećih struktura, primenom savremenih softvera za dinamiku mašina. Projektovanje u slučaju maksimalnih opterećenja ima za cilj da očuva stabilnost strukture, pa se u tom cilju obavljaju vrlo različite simulacije procesa u toku opterećenja. Osnovni odgovori o preraspodeli unutrašnjih sila u strukturi izazvani naglim događajima mogu se tražiti dinamičkom analizom prelaznih stanjatranzijentnom dinamikom. U ovom radu je pokazan postupak simulacije dinamičkog ponašanja toranjske dizalice u toku udarnog radnog opterećenja. U radu je takodje pokazan i razvijen mehanički model structure kao i FEM analizasimulacija ponašanja toranjske dizalice u odabranom ekstremnom režimu rada. Numeričkom analizom pokazan je postupak određivanja nekih najvažnijih podataka za istraživače i konstruktore nastao incidentom, kao što su: najveći napon, zakon kretanja (oscilovanja) i unutrašnje sile strukture. Istraživanja se oslanjaju na rezultate aktuelnih merenja. Numerički je testirana dinamička stabilnost strukture u tranzijentnom režimu sa opterećenjem koje je u granicama maksimalnog opterećenja dizalice. Time je istraživana stabilnosti visokog objekta izloženog dinamici u uslovima opasnih uticaja. Poznavanje ove dinamike ima za cilj monitoring i kontrolu dinamičkih sila u strukturi.
Facta Universitatis, Jan 27, 2018
Accidental actions caused by vibrations of supporting structures in mechanical systems represent ... more Accidental actions caused by vibrations of supporting structures in mechanical systems represent the dynamic tasks of specific scientific and professional research in the field of human and equipment safety. This paper determines the mathematical model of physical excitation force created by human power, based on the discrete-time Fourier transformation. For experimental verification of the model, we made a special platform for measuring bouncing force of people who create natural impulse oscillation. The paper shows the results of individual and group experimental testing of living force as the cause of accidents and dangerous effects on the structure. In the end, the excitation of the human operation of a malicious nature (heavy transport machinecrane) has been used to show the application of Fourier model to simulate one incident. For this purpose, the transient FEM analysis and the eigenvalues predetermined modal analysis are used. The paper is illustrated with photographs of experimental tests of dangerous human impulse in several working machines (objects).
IOP conference series, Aug 10, 2018
Based on experience from the testing of the mining stacker in the copper mine in Bor, a practical... more Based on experience from the testing of the mining stacker in the copper mine in Bor, a practical procedure of frequency simulation of the enforced vibration of the structure was demonstrated. Modelling of the excitation was performed by the harmonic function of the eccentric mass of the belt conveyor drive. The paper shows how the drive frequency excitation affects the amplitude of vibration of the supporting structure. From this, the idea is presentedan algorithm for software that would allow for keeping the dynamic properties of the members of the structure within controlled range. An experiment for accelerating the structure and its FFT analysis in the frequency domain was performed. Dynamic modelling of the structure allows obtaining the objectivised concept of the measurement system for monitoring based on the given level of dynamic sensitivity of the parts of the structure.
Etri Journal, May 4, 2016
Универзитет у Нишу, Sep 27, 2016
The doctoral dissertation deals with incidents of heavy lifting and construction machinery. The r... more The doctoral dissertation deals with incidents of heavy lifting and construction machinery. The research studies the stability and the risk of mechanical systems at the dynamic impulse influences which determine the safety of supporting structures. Typical incident events, at work of machinery, which influence in unique way on placed modelling and dynamical simulation, here are selected. The surveys on a group of five types of machines were carried out whereby the models of numerical simulations were developed, with the help of five experimental investigations of the structures for supporting model verification. The results of the disertation are: Exact identification of dangerous forced vibration frequencies; Mathematical formulation of incidental excitation forces; Mathematical forms of wind excitation forces with medium strength in multiple gusts; Geometry of frame structures with low dynamic stability; Mathematical forms of malicious excitations with large vibration amplitudes. Elements of risk are separated and defined: high accelerations, large deflections, shaking (tremor), extreme dynamic coefficients, loss of contact of structural parts. The finite element method (FEM) is applied in transient dynamic analysis of mechanical system. The experiments on tower crane, bridge crane, shipbuilding (levelluffing) crane, mining stacker and mobile elevating platform were performed. The obtained technical models are an incidental design template which checks sensitivity on extreme and unexpected influences.
Structural Engineering and Mechanics, 2019
This paper gives a contribution to solution of problem: "what kind of vehicles to choose?&qu... more This paper gives a contribution to solution of problem: "what kind of vehicles to choose?". The optimal choosing of vehicle is problem that is immanent in communal enterprises. The best technical solution isn't the most expensive usually, but it isn't and the cheapest. In the paper is presented the universal model for choosing of appropriate solution of vehicle for using in any business system. The model can be applied for the choosing of garbage collection truck. The model is based to multicriterial approach. According to given model, the choosing of vehicle contains five key activities. Process for the choosing of vehicle is presented step by step. This model includes transport requests and waste management system requests. The paper emphasizes importance of specific criteria resulting waste management system. In the paper are explained notion and split of special communal vehicles and garbage collection trucks especially. The paper insists to definition of speci...
This paper contributes to the research of rhythmic behavior of a group of people, which, more or ... more This paper contributes to the research of rhythmic behavior of a group of people, which, more or less synchronized, moves or jumps on a thin and elastic plate, thus performing a dynamically variable load. The analysis of the rhythmic behaviour of the crowd carried out on the basis of the experimental testing on the special steel test platform. The experiment consisted of sixteen measurements of live force and acceleration of the test platform. The dynamic loads caused by the mass of the human crowd and individuals had different intensities. The measurements of acceleration of the test platform were performed in order to estimate how the live human force influences on vibrations of machine structures. This research allows us to gain a picture of how serious the threats are from some human actions on the support structure of machines that are handled when performing works in industry, construction or mining. On the basis of these experiments, the mathematical models of the equivalent ...
An important aspect of the support structures' design is their dynamic behavior under extreme... more An important aspect of the support structures' design is their dynamic behavior under extreme conditions. Especially actual are the large-range structures. Therefore, the support structure of a mining machine for transportation of tailings (stacker) is observed dynamically. The dynamic behavior of the entire structure in an incidental situation – the failure of a support tie rod for the pylon-platform connection is observed. The aim of this research is to predict the consequences of breaking a structure element for the rest of the support structure. This paper shows the theoretical modeling of structures, numerical solution of differential equations, and vibrations after simulated incident. The paper presents special design – the way of structure testing from the aspect of high structural availability and ability of the structure to compensate overload caused by the incident. To check the model, a real stacker structure was used at the surface mine RBB (The copper mine – Bor, Se...
Climate changes on the planet have led to the appearance of extreme natural influences on large s... more Climate changes on the planet have led to the appearance of extreme natural influences on large structures in ports and shipyards, as well as at-sea structures. One of the most variable meteorological effects in space and time is the wind. This paper provides the manner of dynamic modelling of wind loads on a tall portal-rotating crane structure. The gust of wind is modelled as a wave quantity variable in time and altitude of flow. Dynamic wind activity on tall structures is used to obtain a structure’s behaviour with regard to extreme climate events when frequently resonant influences occur. This is performed by non-linear transient FEM analysis. Structural damping is modelled by conversion to the equivalent viscous damping. Eigenfrequencies are obtained by applying the Lanczos method which combines the tracking method and the transformation method. The paper contains an originally developed dynamic model, experimentally verified stiffness, and internal static quantities. The aim o...
Double Boom Level-Luffing mechanism (with joint connected parts) is typical cranes structure at s... more Double Boom Level-Luffing mechanism (with joint connected parts) is typical cranes structure at shipyard in the world. Cranes using these systems are characterized by heights over 80 meters and their weight often exceeding 500 tons. The importance of such large cranes imposes a need for detailed study of their dynamic behavior. This paper provides an overview of experimental and theoretical research of the reach changing system. At the same time, the main tasks for the engineers, analysts, researchers and manufacturers are indicated. The paper shows the results of existing cranes experimental tests (its real dynamic properties). The paper also shows the most suitable way of theoretical modeling of supporting structure and calculations of internal dynamic forces. The obtained results in the paper indicate a high level of internal forces and energy and thus the importance of a reliable system design for the reach change.
IMK-14 - Istrazivanje i razvoj, 2016
U nedostatku eksperimentalnih analiza vibracija, mogu se uspešno vršiti numeričke analize nosećih... more U nedostatku eksperimentalnih analiza vibracija, mogu se uspešno vršiti numeričke analize nosećih struktura, primenom savremenih softvera za dinamiku mašina. Projektovanje u slučaju maksimalnih opterećenja ima za cilj da očuva stabilnost strukture, pa se u tom cilju obavljaju vrlo različite simulacije procesa u toku opterećenja. Osnovni odgovori o preraspodeli unutrašnjih sila u strukturi izazvani naglim događajima mogu se tražiti dinamičkom analizom prelaznih stanjatranzijentnom dinamikom. U ovom radu je pokazan postupak simulacije dinamičkog ponašanja toranjske dizalice u toku udarnog radnog opterećenja. U radu je takodje pokazan i razvijen mehanički model structure kao i FEM analizasimulacija ponašanja toranjske dizalice u odabranom ekstremnom režimu rada. Numeričkom analizom pokazan je postupak određivanja nekih najvažnijih podataka za istraživače i konstruktore nastao incidentom, kao što su: najveći napon, zakon kretanja (oscilovanja) i unutrašnje sile strukture. Istraživanja se oslanjaju na rezultate aktuelnih merenja. Numerički je testirana dinamička stabilnost strukture u tranzijentnom režimu sa opterećenjem koje je u granicama maksimalnog opterećenja dizalice. Time je istraživana stabilnosti visokog objekta izloženog dinamici u uslovima opasnih uticaja. Poznavanje ove dinamike ima za cilj monitoring i kontrolu dinamičkih sila u strukturi.
IOP Conference Series: Materials Science and Engineering, 2018
Based on experience from the testing of the mining stacker in the copper mine in Bor, a practical... more Based on experience from the testing of the mining stacker in the copper mine in Bor, a practical procedure of frequency simulation of the enforced vibration of the structure was demonstrated. Modelling of the excitation was performed by the harmonic function of the eccentric mass of the belt conveyor drive. The paper shows how the drive frequency excitation affects the amplitude of vibration of the supporting structure. From this, the idea is presentedan algorithm for software that would allow for keeping the dynamic properties of the members of the structure within controlled range. An experiment for accelerating the structure and its FFT analysis in the frequency domain was performed. Dynamic modelling of the structure allows obtaining the objectivised concept of the measurement system for monitoring based on the given level of dynamic sensitivity of the parts of the structure.
Facta Universitatis, Series: Working and Living Environmental Protection, 2018
Accidental actions caused by vibrations of supporting structures in mechanical systems represent ... more Accidental actions caused by vibrations of supporting structures in mechanical systems represent the dynamic tasks of specific scientific and professional research in the field of human and equipment safety. This paper determines the mathematical model of physical excitation force created by human power, based on the discrete-time Fourier transformation. For experimental verification of the model, we made a special platform for measuring bouncing force of people who create natural impulse oscillation. The paper shows the results of individual and group experimental testing of living force as the cause of accidents and dangerous effects on the structure. In the end, the excitation of the human operation of a malicious nature (heavy transport machine – crane) has been used to show the application of Fourier model to simulate one incident. For this purpose, the transient FEM analysis and the eigenvalues predetermined modal analysis are used. The paper is illustrated with photographs ...
Journal of Applied Engineering Science, 2018
This paper presents the investigation of importancefor determining the dynamic structural respons... more This paper presents the investigation of importancefor determining the dynamic structural response of heavy lifting machines subjected to extreme external effects. A measuring system for the experimental investigation of the dynamics of heavy lifting machines is proposed.It shows the experimental testing results of carrying structures for several classes of hoisting and an export mining machine. The results refer to the most important dynamic parameters. The dynamic parameters also include the duration of transient phenomena in handling lifting structures and structural damping.A technical solution based on the measuring chain that is integrated into the mining export plant information system was developed in the research. The recommendation to choose optimal measuring equipment for this kind of measurement is given to manufacturers and users on the basis of the experience gained in the design and implementation of specifi c measuring systems. The technical specifi cation of amplifi ers and transducers that should be developed for this kind of measurement is also proposed.
Structural Engineering and Mechanics, 2014
A simulation of failures on responsible elements is only one form of the extreme structural behav... more A simulation of failures on responsible elements is only one form of the extreme structural behavior analysis. By understanding the dynamic behavior in incidental situations, it is possible to make a special structural design from the point of the largest axial force, stress and redundancy. The numerical realization of one such simulation analysis was performed using FEM in this paper. The boundary parameters of transient analysis, such as overall structural damping coefficient, load accelerations, time of load fall and internal forces in the responsible structural elements, were determined on the basis of the dynamic experimental parameters. The structure eigenfrequencies were determined in modal analysis. In the study, the basic incidental models were set. The models were identified by many years of monitoring incidental situations and the most frequent human errors in work with heavy structures. The combined load models of structure are defined in the paper since the incidents simply arise as consequences of cumulative errors and failures. A feature of a combined model is that the single incident causes the next incident (consecutive timing) as well as that other simple dynamic actions are simultaneous. The structure was observed in three typical load positions taken from the crane passport (range-load). The obtained dynamic responses indicate the degree of structural sensitivity depending on the character of incident. The dynamic coefficient KD was adopted as a parameter for the evaluation of structural sensitivity.
The quality of the model used to describe a structure is the main value of the scientific selecti... more The quality of the model used to describe a structure is the main value of the scientific selection of technical analyses. This theoretical-experimental analysis shows the quality of modern dynamic modeling when it comes to modeling structures using linear members (1D finite elements). A tower crane structure is observed as a representative of large structures. A FEM structure model is created and subjected to testing of its static and dynamic properties. Elastic displacements and forms of model oscillations are searched for. Numerically obtained theoretical solutions are compared to experimental results. The quality of modern structure modeling application has a deviation of less than 2%. At the locations of the pronounced bending of the lattice, in the structure of the cantilever type, the elastic displacement deviation is less than 3%. The differences in the results of theoretical models and of experimental studies indicate the sensitivity of modeling quality depending on the experience of the authors and the restrictions of theoretical models in the description of connections in the truss node. The paper points to the elements of quality modeling, the scope of the number of applied structure elements, the redundant detailedness of some descriptions, the importance of the finite element type selection, the experimental values of vibration damping and the tower cranes properties. On the basis of these analyses, it is possible to develop analogue models which assure the quality-precision in modeling responsible structures.
Istraživanja i projektovanja za privredu, 2018
This paper presents the investigation of importancefor determining the dynamic structural respons... more This paper presents the investigation of importancefor determining the dynamic structural response of heavy lifting machines subjected to extreme external effects. A measuring system for the experimental investigation of the dynamics of heavy lifting machines is proposed.It shows the experimental testing results of carrying structures for several classes of hoisting and an export mining machine. The results refer to the most important dynamic parameters. The dynamic parameters also include the duration of transient phenomena in handling lifting structures and structural damping.A technical solution based on the measuring chain that is integrated into the mining export plant information system was developed in the research. The recommendation to choose optimal measuring equipment for this kind of measurement is given to manufacturers and users on the basis of the experience gained in the design and implementation of specifi c measuring systems. The technical specifi cation of amplifi ers and transducers that should be developed for this kind of measurement is also proposed.
This paper gives a contribution to solution of problem: "what kind of vehicles to choose?&qu... more This paper gives a contribution to solution of problem: "what kind of vehicles to choose?". The optimal choosing of vehicle is problem that is immanent in communal enterprises. The best technical solution isn't the most expensive usually, but it isn't and the cheapest. In the paper is presented the universal model for choosing of appropriate solution of vehicle for using in any business system. The model can be applied for the choosing of garbage collection truck. The model is based to multicriterial approach. According to given model, the choosing of vehicle contains five key activities. Process for the choosing of vehicle is presented step by step. This model includes transport requests and waste management system requests. The paper emphasizes importance of specific criteria resulting waste management system. In the paper are explained notion and split of special communal vehicles and garbage collection trucks especially. The paper insists to definition of special communal vehicles which use for special transport and which are equipped with necessary content for loading/unloading or other work function. In the paper is indicated to importance of costs, also and importance of organization and conception of maintenance for the procedure of choosing alternative vehicle. This paper indicates on necessary connecting of tree key factors: choosing of vehicle, quality maintaining and good logistics, in objective of implementation the best performances of transport system. .
IMK-14, 2016
U nedostatku eksperimentalnih analiza vibracija, mogu se uspešno vršiti numeričke analize nosećih... more U nedostatku eksperimentalnih analiza vibracija, mogu se uspešno vršiti numeričke analize nosećih struktura, primenom savremenih softvera za dinamiku mašina. Projektovanje u slučaju maksimalnih opterećenja ima za cilj da očuva stabilnost strukture, pa se u tom cilju obavljaju vrlo različite simulacije procesa u toku opterećenja. Osnovni odgovori o preraspodeli unutrašnjih sila u strukturi izazvani naglim događajima mogu se tražiti dinamičkom analizom prelaznih stanjatranzijentnom dinamikom. U ovom radu je pokazan postupak simulacije dinamičkog ponašanja toranjske dizalice u toku udarnog radnog opterećenja. U radu je takodje pokazan i razvijen mehanički model structure kao i FEM analizasimulacija ponašanja toranjske dizalice u odabranom ekstremnom režimu rada. Numeričkom analizom pokazan je postupak određivanja nekih najvažnijih podataka za istraživače i konstruktore nastao incidentom, kao što su: najveći napon, zakon kretanja (oscilovanja) i unutrašnje sile strukture. Istraživanja se oslanjaju na rezultate aktuelnih merenja. Numerički je testirana dinamička stabilnost strukture u tranzijentnom režimu sa opterećenjem koje je u granicama maksimalnog opterećenja dizalice. Time je istraživana stabilnosti visokog objekta izloženog dinamici u uslovima opasnih uticaja. Poznavanje ove dinamike ima za cilj monitoring i kontrolu dinamičkih sila u strukturi.
Facta Universitatis, Jan 27, 2018
Accidental actions caused by vibrations of supporting structures in mechanical systems represent ... more Accidental actions caused by vibrations of supporting structures in mechanical systems represent the dynamic tasks of specific scientific and professional research in the field of human and equipment safety. This paper determines the mathematical model of physical excitation force created by human power, based on the discrete-time Fourier transformation. For experimental verification of the model, we made a special platform for measuring bouncing force of people who create natural impulse oscillation. The paper shows the results of individual and group experimental testing of living force as the cause of accidents and dangerous effects on the structure. In the end, the excitation of the human operation of a malicious nature (heavy transport machinecrane) has been used to show the application of Fourier model to simulate one incident. For this purpose, the transient FEM analysis and the eigenvalues predetermined modal analysis are used. The paper is illustrated with photographs of experimental tests of dangerous human impulse in several working machines (objects).
IOP conference series, Aug 10, 2018
Based on experience from the testing of the mining stacker in the copper mine in Bor, a practical... more Based on experience from the testing of the mining stacker in the copper mine in Bor, a practical procedure of frequency simulation of the enforced vibration of the structure was demonstrated. Modelling of the excitation was performed by the harmonic function of the eccentric mass of the belt conveyor drive. The paper shows how the drive frequency excitation affects the amplitude of vibration of the supporting structure. From this, the idea is presentedan algorithm for software that would allow for keeping the dynamic properties of the members of the structure within controlled range. An experiment for accelerating the structure and its FFT analysis in the frequency domain was performed. Dynamic modelling of the structure allows obtaining the objectivised concept of the measurement system for monitoring based on the given level of dynamic sensitivity of the parts of the structure.
Etri Journal, May 4, 2016
Универзитет у Нишу, Sep 27, 2016
The doctoral dissertation deals with incidents of heavy lifting and construction machinery. The r... more The doctoral dissertation deals with incidents of heavy lifting and construction machinery. The research studies the stability and the risk of mechanical systems at the dynamic impulse influences which determine the safety of supporting structures. Typical incident events, at work of machinery, which influence in unique way on placed modelling and dynamical simulation, here are selected. The surveys on a group of five types of machines were carried out whereby the models of numerical simulations were developed, with the help of five experimental investigations of the structures for supporting model verification. The results of the disertation are: Exact identification of dangerous forced vibration frequencies; Mathematical formulation of incidental excitation forces; Mathematical forms of wind excitation forces with medium strength in multiple gusts; Geometry of frame structures with low dynamic stability; Mathematical forms of malicious excitations with large vibration amplitudes. Elements of risk are separated and defined: high accelerations, large deflections, shaking (tremor), extreme dynamic coefficients, loss of contact of structural parts. The finite element method (FEM) is applied in transient dynamic analysis of mechanical system. The experiments on tower crane, bridge crane, shipbuilding (levelluffing) crane, mining stacker and mobile elevating platform were performed. The obtained technical models are an incidental design template which checks sensitivity on extreme and unexpected influences.
Structural Engineering and Mechanics, 2019
This paper gives a contribution to solution of problem: "what kind of vehicles to choose?&qu... more This paper gives a contribution to solution of problem: "what kind of vehicles to choose?". The optimal choosing of vehicle is problem that is immanent in communal enterprises. The best technical solution isn't the most expensive usually, but it isn't and the cheapest. In the paper is presented the universal model for choosing of appropriate solution of vehicle for using in any business system. The model can be applied for the choosing of garbage collection truck. The model is based to multicriterial approach. According to given model, the choosing of vehicle contains five key activities. Process for the choosing of vehicle is presented step by step. This model includes transport requests and waste management system requests. The paper emphasizes importance of specific criteria resulting waste management system. In the paper are explained notion and split of special communal vehicles and garbage collection trucks especially. The paper insists to definition of speci...
This paper contributes to the research of rhythmic behavior of a group of people, which, more or ... more This paper contributes to the research of rhythmic behavior of a group of people, which, more or less synchronized, moves or jumps on a thin and elastic plate, thus performing a dynamically variable load. The analysis of the rhythmic behaviour of the crowd carried out on the basis of the experimental testing on the special steel test platform. The experiment consisted of sixteen measurements of live force and acceleration of the test platform. The dynamic loads caused by the mass of the human crowd and individuals had different intensities. The measurements of acceleration of the test platform were performed in order to estimate how the live human force influences on vibrations of machine structures. This research allows us to gain a picture of how serious the threats are from some human actions on the support structure of machines that are handled when performing works in industry, construction or mining. On the basis of these experiments, the mathematical models of the equivalent ...
An important aspect of the support structures' design is their dynamic behavior under extreme... more An important aspect of the support structures' design is their dynamic behavior under extreme conditions. Especially actual are the large-range structures. Therefore, the support structure of a mining machine for transportation of tailings (stacker) is observed dynamically. The dynamic behavior of the entire structure in an incidental situation – the failure of a support tie rod for the pylon-platform connection is observed. The aim of this research is to predict the consequences of breaking a structure element for the rest of the support structure. This paper shows the theoretical modeling of structures, numerical solution of differential equations, and vibrations after simulated incident. The paper presents special design – the way of structure testing from the aspect of high structural availability and ability of the structure to compensate overload caused by the incident. To check the model, a real stacker structure was used at the surface mine RBB (The copper mine – Bor, Se...
Climate changes on the planet have led to the appearance of extreme natural influences on large s... more Climate changes on the planet have led to the appearance of extreme natural influences on large structures in ports and shipyards, as well as at-sea structures. One of the most variable meteorological effects in space and time is the wind. This paper provides the manner of dynamic modelling of wind loads on a tall portal-rotating crane structure. The gust of wind is modelled as a wave quantity variable in time and altitude of flow. Dynamic wind activity on tall structures is used to obtain a structure’s behaviour with regard to extreme climate events when frequently resonant influences occur. This is performed by non-linear transient FEM analysis. Structural damping is modelled by conversion to the equivalent viscous damping. Eigenfrequencies are obtained by applying the Lanczos method which combines the tracking method and the transformation method. The paper contains an originally developed dynamic model, experimentally verified stiffness, and internal static quantities. The aim o...
Double Boom Level-Luffing mechanism (with joint connected parts) is typical cranes structure at s... more Double Boom Level-Luffing mechanism (with joint connected parts) is typical cranes structure at shipyard in the world. Cranes using these systems are characterized by heights over 80 meters and their weight often exceeding 500 tons. The importance of such large cranes imposes a need for detailed study of their dynamic behavior. This paper provides an overview of experimental and theoretical research of the reach changing system. At the same time, the main tasks for the engineers, analysts, researchers and manufacturers are indicated. The paper shows the results of existing cranes experimental tests (its real dynamic properties). The paper also shows the most suitable way of theoretical modeling of supporting structure and calculations of internal dynamic forces. The obtained results in the paper indicate a high level of internal forces and energy and thus the importance of a reliable system design for the reach change.
IMK-14 - Istrazivanje i razvoj, 2016
U nedostatku eksperimentalnih analiza vibracija, mogu se uspešno vršiti numeričke analize nosećih... more U nedostatku eksperimentalnih analiza vibracija, mogu se uspešno vršiti numeričke analize nosećih struktura, primenom savremenih softvera za dinamiku mašina. Projektovanje u slučaju maksimalnih opterećenja ima za cilj da očuva stabilnost strukture, pa se u tom cilju obavljaju vrlo različite simulacije procesa u toku opterećenja. Osnovni odgovori o preraspodeli unutrašnjih sila u strukturi izazvani naglim događajima mogu se tražiti dinamičkom analizom prelaznih stanjatranzijentnom dinamikom. U ovom radu je pokazan postupak simulacije dinamičkog ponašanja toranjske dizalice u toku udarnog radnog opterećenja. U radu je takodje pokazan i razvijen mehanički model structure kao i FEM analizasimulacija ponašanja toranjske dizalice u odabranom ekstremnom režimu rada. Numeričkom analizom pokazan je postupak određivanja nekih najvažnijih podataka za istraživače i konstruktore nastao incidentom, kao što su: najveći napon, zakon kretanja (oscilovanja) i unutrašnje sile strukture. Istraživanja se oslanjaju na rezultate aktuelnih merenja. Numerički je testirana dinamička stabilnost strukture u tranzijentnom režimu sa opterećenjem koje je u granicama maksimalnog opterećenja dizalice. Time je istraživana stabilnosti visokog objekta izloženog dinamici u uslovima opasnih uticaja. Poznavanje ove dinamike ima za cilj monitoring i kontrolu dinamičkih sila u strukturi.
IOP Conference Series: Materials Science and Engineering, 2018
Based on experience from the testing of the mining stacker in the copper mine in Bor, a practical... more Based on experience from the testing of the mining stacker in the copper mine in Bor, a practical procedure of frequency simulation of the enforced vibration of the structure was demonstrated. Modelling of the excitation was performed by the harmonic function of the eccentric mass of the belt conveyor drive. The paper shows how the drive frequency excitation affects the amplitude of vibration of the supporting structure. From this, the idea is presentedan algorithm for software that would allow for keeping the dynamic properties of the members of the structure within controlled range. An experiment for accelerating the structure and its FFT analysis in the frequency domain was performed. Dynamic modelling of the structure allows obtaining the objectivised concept of the measurement system for monitoring based on the given level of dynamic sensitivity of the parts of the structure.
Facta Universitatis, Series: Working and Living Environmental Protection, 2018
Accidental actions caused by vibrations of supporting structures in mechanical systems represent ... more Accidental actions caused by vibrations of supporting structures in mechanical systems represent the dynamic tasks of specific scientific and professional research in the field of human and equipment safety. This paper determines the mathematical model of physical excitation force created by human power, based on the discrete-time Fourier transformation. For experimental verification of the model, we made a special platform for measuring bouncing force of people who create natural impulse oscillation. The paper shows the results of individual and group experimental testing of living force as the cause of accidents and dangerous effects on the structure. In the end, the excitation of the human operation of a malicious nature (heavy transport machine – crane) has been used to show the application of Fourier model to simulate one incident. For this purpose, the transient FEM analysis and the eigenvalues predetermined modal analysis are used. The paper is illustrated with photographs ...
Journal of Applied Engineering Science, 2018
This paper presents the investigation of importancefor determining the dynamic structural respons... more This paper presents the investigation of importancefor determining the dynamic structural response of heavy lifting machines subjected to extreme external effects. A measuring system for the experimental investigation of the dynamics of heavy lifting machines is proposed.It shows the experimental testing results of carrying structures for several classes of hoisting and an export mining machine. The results refer to the most important dynamic parameters. The dynamic parameters also include the duration of transient phenomena in handling lifting structures and structural damping.A technical solution based on the measuring chain that is integrated into the mining export plant information system was developed in the research. The recommendation to choose optimal measuring equipment for this kind of measurement is given to manufacturers and users on the basis of the experience gained in the design and implementation of specifi c measuring systems. The technical specifi cation of amplifi ers and transducers that should be developed for this kind of measurement is also proposed.
Structural Engineering and Mechanics, 2014
A simulation of failures on responsible elements is only one form of the extreme structural behav... more A simulation of failures on responsible elements is only one form of the extreme structural behavior analysis. By understanding the dynamic behavior in incidental situations, it is possible to make a special structural design from the point of the largest axial force, stress and redundancy. The numerical realization of one such simulation analysis was performed using FEM in this paper. The boundary parameters of transient analysis, such as overall structural damping coefficient, load accelerations, time of load fall and internal forces in the responsible structural elements, were determined on the basis of the dynamic experimental parameters. The structure eigenfrequencies were determined in modal analysis. In the study, the basic incidental models were set. The models were identified by many years of monitoring incidental situations and the most frequent human errors in work with heavy structures. The combined load models of structure are defined in the paper since the incidents simply arise as consequences of cumulative errors and failures. A feature of a combined model is that the single incident causes the next incident (consecutive timing) as well as that other simple dynamic actions are simultaneous. The structure was observed in three typical load positions taken from the crane passport (range-load). The obtained dynamic responses indicate the degree of structural sensitivity depending on the character of incident. The dynamic coefficient KD was adopted as a parameter for the evaluation of structural sensitivity.