IOP Conference Series: Materials Science and Engineering, 2016
The article analyzes the deformations that are created in a circular plate with radial ribs locat... more The article analyzes the deformations that are created in a circular plate with radial ribs located on one side, under a concentrated force located at it's center, F =77000N. To this purpose the deflection obtained by analytically calculating is determined and compares with the displacement obtained by finite element method. To obtain the vertical displacements of a ribbed plate, the results of a similar plane plate, whose vertical displacements were determined, were used and displacements and tensions parameter value, as determined by the analytical method, were introduced.
The article analyzes the deformations that are created in a circular plate with radial ribs locat... more The article analyzes the deformations that are created in a circular plate with radial ribs located on one side, under a concentrated force located at it's center, F =77000N. To this purpose the deflection obtained by analytically calculating is determined and compares with the displacement obtained by finite element method. To obtain the vertical displacements of a ribbed plate, the results of a similar plane plate, whose vertical displacements were determined, were used and displacements and tensions parameter value, as determined by the analytical method, were introduced.
The Scientific Bulletin of "Valahia" University, Oct 1, 2022
Nanotechnology has a large area of applications, from devices to equipments from physics, enginee... more Nanotechnology has a large area of applications, from devices to equipments from physics, engineering, chemistry and biology. Nanostructures are used in materials engoineering, mecanics, synthesis, antifungic activity protocols and cultural heritage.
Scientific Bulletin of Valahia University - Materials and Mechanics
Inertial vibrating screens operating in resonance and post-resonance mode represent a class of sc... more Inertial vibrating screens operating in resonance and post-resonance mode represent a class of screens that present a series of advantages: simple construction and maintenance, high flow rates, low energy consumption, low level of vibrations transmitted to the building in which they are located, high screening efficiency. Due to these advantages, they tend to replace all other types of screens. However, these cisterns are very sensitive to variations in the supply flow, therefore they must be equipped with electronic control devices and automatic control of the supply flow with mineral aggregates. The present paper presents a numerical simulation of the variation of the vibration amplitudes for different values of the material on the screen using the professional calculation program MATHCAD 14.
Continuous beams are statically indeterminate systems (hyperstatic systems). New analytical metho... more Continuous beams are statically indeterminate systems (hyperstatic systems). New analytical methods based on matrix calculation are currently being used to solve such problems, which allow obtaining reactions. Using the MATHCAD professional program you can solve matrix equations and also you can get diagrams of variation of sectional efforts, displacements and rotations of sections along the entire length of the bar. This paper presents the matrix method for solving a particular problem of a beam located on seven prestressed elastic supports for compression.
In the engineering practice, knowing the technical condition of industrial equipment under operat... more In the engineering practice, knowing the technical condition of industrial equipment under operating shortening duration of the repair machinery, smart planning repairs to evolving wear while machine parts in motion, detecting and correcting errors in the installation or repair. They are some of the important objectives; maintenance engineer must follow to prevent damage to equipment and removing them permanently from operation and ensure repair costs as low as possible. The purpose of this paper is to present a case study on vibro-acoustical diagnosis of equipment and components subject to wear during operation to prevent damage to their catastrophic and the human and material losses.
Artificial muscles are likely to be essential components of robotics, and a variety of micro-mach... more Artificial muscles are likely to be essential components of robotics, and a variety of micro-machinery. The artificial muscles, have the potential to allow future robots to operate with superior muscle elasticity and isometric stress generation, even at extreme temperatures. Some new nanofibers for an artificial muscle is presented in this paper. The artificial muscle is based on a contractile polymer gel which undergoes abrupt volume changes in response to variations in external conditions. The tubes and wetting surfaces of the valves are constructed from teflon which is chemically inert and the fibers are made from Poly-Vinyl Alcohol PVA, alone or with PMMA and as magnetic polymer, with magnetite.
With quality control being an important issue in industry, there is a great need for free form su... more With quality control being an important issue in industry, there is a great need for free form surfaces measurements in manufacturing. With manufacturing processes becoming increasingly more flexible, there is also a demand for increasing flexibility of measuring machines. This paper describes the process of developing an automatic measurement system for any free-form surfaces. We present a system for 3D surfaces measurement with three inter-changeable measurement heads which can be easy mounted on its Z axis and allow contact or non-contact measurements. The paper presents also some considerations about error sources and system calibration. This system is developed under the project: „Researches on advanced control techniques based on the analysis of errors and three-dimensional modeling for a high precision measurement of the complex surfaces”funded by National Program Partnerships in Priority Areas.
The rotary drums are technological equipments used in manufacturing clinker cement materials, coo... more The rotary drums are technological equipments used in manufacturing clinker cement materials, cooling cement clinker, cooling burnt pyrites exhausted from roasting furnace lines of sulfuric acid, cooling alumina discharged from calcination ovens, cooling lime exhausted from lime ovens, cooling slag from chemical fertilizer furnaces, etc. Rotary drums are also used in mixing of powder or granular materials, separation and enrichment of ore, coal, etc.., washing ores and other minerals, crystallization and extraction of sugar from sugar beets, etc.., drying various raw materials for cement clinker, clay, marl, furnace slag, coal, grain, etc.. This paper presents some contributions of application using MATHCAD 14 program into design and verification of loose riding rings mounted on support blocks included in the equipment’s bearing group.
The project “ The Development of Education for the viability of labour market through the innovat... more The project “ The Development of Education for the viability of labour market through the innovative vectors: MECHATRONICS ‐ INTEGRONICS (M&I) ”, financed by the Sector Operational Programme Human Resources Romania 2007÷2013, responds to the directives of the Key Aria of Intervention 2.1 from the priority axis 2: Call for project proposal no. 90 ‐ Learn a trade, on: carrying out a wide set of activities for promoting the new HIGH-TECH ADVANCED field of MECHATRONICS & INTEGRONICS, on the internal labour market, especially in the ranks of university higher education graduates . This apex field is an integrative science that offers a wide perspective on the contribution of science and technology to the unfolding of the programmes corresponding to the national strategies for sustainable economic development and aligning to the ones promoted at the community level.
Scientific Bulletin of Valahia University - Materials and Mechanics, 2018
The implementation of proactive maintenance is a necessity required by the development of modern ... more The implementation of proactive maintenance is a necessity required by the development of modern technologies for the monitoring and exploitation of energy facilities and equipment. An important advantage of proactive maintenance is to permanently monitor the technical condition of the plant and equipment by vibration measurements and in the correct diagnosis in order to reasonably plan the required repairs. Turbo-aggregates are autonomous complex installations for producing electricity in refineries that operate in high power and high-speed modes. To monitor and control turbine vibrations, vibration sensors (uniaxial, biaxial and triaxial accelerometers) and proximity sensors (for relative displacements and lasers) are columned on bearing housings that transmit signals to data acquisition and processing systems as well is the Vibro-Expret diagnosis system presented in this paper.
Scientific Bulletin of Valahia University - Materials and Mechanics, 2017
One important objectives of proactive maintenance are the knowledge of the technical state of mac... more One important objectives of proactive maintenance are the knowledge of the technical state of machinery, the intelligent planning of interventions according to the diagnosis technique, identification and correction of assembling errors. The aim of this paper is to present a new case on the vibrations diagnosis of hydro-aggregate CAMPELA - CHE Dubasari (MOLDOVA). The VIBRO EXPERT diagnostic system used on the CAPMELA hydro-aggregate is designed to measure, monitor, diagnose, and analyze the technical and functional parameters in order to safe use of the hydro-aggregate turbine, using the vibrations data measurement. The proactive maintenance concept is being used more and more thanks to the development of these intelligent monitoring and control systems, in order to prevent interruptions due to major failures.
International Journal of Mechatronics and Applied Mechanics, 2018
Proactive maintenance is a relatively new concept used today by the exploitation of manufacturing... more Proactive maintenance is a relatively new concept used today by the exploitation of manufacturing and energy production systems consisting of vibro acoustic monitoring of installations and equipment with professional equipment, such as Expret-Vibro and PROFISIGNAL software. These vibration level measurements are required for vibro acoustic diagnosis and for timely programming of repairs that are being challenged before accidental malfunctions occur. Electric steam turbines are used to produce electrical energy in refineries, which are particularly complex and are equipped with a turbine shaft located on several sliding or rolling bearings. Vibration sensors are mounted on bearing housings and are formed from one-axial, biaxial and three-axial accelerometers for absolute magnitudes (P-P and RMS speeds) or laser proximal sensors (relative and offset displacements). These sensors transmit the signals of data acquisition cards and amplifiers for data processing
Scientific Bulletin of Valahia University - Materials and Mechanics, 2019
There is a direct analogy between the mechanical and electrical phenomena related to vibrations a... more There is a direct analogy between the mechanical and electrical phenomena related to vibrations and electromagnetic oscillations in the RLC series AC circuits and an inverse analogy to the electromagnetic oscillations in the RLC parallel alternative current (AC) circuits. Direct analogy RLC series AC circuit refers to the connection between complex velocity and complex electrical intensity, mechanical impedance and electrical impedance, etc. Reverse analogy RLC parallel AC circuits refers to the connection between complex velocity and complex electrical voltage, mechanical impedance and electrical admission, etc.
International Journal of Mechatronics and Applied Mechanics, 2017
Permanent knowledge of the technical state of rotating turbines, intelligent planning of interven... more Permanent knowledge of the technical state of rotating turbines, intelligent planning of interventions according to the evolution of vibrations parameters, identification and correction of mounting errors, are the important objectives of proactive maintenance that the operating engineer must pursue for avoidance disruptions or definitive decommissioning. The purpose of this paper is to present a case study on the vibrations diagnosis of hydro-aggregate CAMPELA HA1-CHE Dubasari/12 MW /120 RPM. The Vibro Expert diagnosis system mounted on CAPMELA is designed to measure, monitor, diagnose, predict and analyze the main technical and functional parameters of the hydro-aggregate in order to exploit it in maximum safety.
Scientific Bulletin of Valahia University - Materials and Mechanics, 2016
In the engineering practice, knowing the technical condition of industrial equipment under operat... more In the engineering practice, knowing the technical condition of industrial equipment under operating results shortening of repairs, repairs machinery to smart planning based on the time evolution of bearing wear, detect and correct errors on their installation or repair. This is one of the most important objectives of proactive maintenance; maintenance engineer must follow and monitor the wear of equipment with moving parts to prevent damage and removing them permanently from service, ensuring repair costs as low as possible. The aim of this paper is to present a particular case study on vibro- acoustic diagnosis of equipment and components subject to wear during operation to prevent catastrophic damage, as well as human and material losses.
Scientific Bulletin of Valahia University - Materials and Mechanics, 2017
According to the IWA norms, the water loss category includes also the apparent loss water due to ... more According to the IWA norms, the water loss category includes also the apparent loss water due to measurement errors of the water meters used at the connections. This paper presents the experimental results obtained during two years of registrations in TARGOVISTE’s Water Company network. A program for verifying the water meters used for connections has been implemented according to a statistical distribution, depending on the number of appliances and their dimensions. Using a theoretical simulation model, calibrated on the basis of the actual reference flows measured on the metrology approved measuring stand, a procedure was developed to assess the level of deviations in the fully metered water distribution network. Depending on the values of deviations and flows actually recorded by the meters in the distribution network, it was possible to estimate the percentage of the losses from the actually used water meters.
The actual graphical methods used by engineers when plotting the stress distributions are based o... more The actual graphical methods used by engineers when plotting the stress distributions are based on integrating the differential equations of stresses for each beam segment. The resulting integration constants are obtained by imposing boundary conditions for each beam segment. Using MATHCAD, this alternative proposed analytical method uses the step function Φ(x-a) which introduces a compact form of the stresses and displacements expressions. The constructive optimization is thus easier to be performed.
The authors have proposed to show the advantages of different specialized software that can used ... more The authors have proposed to show the advantages of different specialized software that can used in solving the algebraic and transcendental differential equations applied in mechanics, as problems of material point relative motion dynamics. Index Terms-dynamics, equations, software I. INTRODUCTION One considers the following problem: Inside a tube OA a material point M of mass m slides with friction (fig. 1). In the same time the tube is rotating with the angular velocity ω, around a vertical axis which intersects its ends. In this example the absolute and relative motion of the material point will be studied considering the following cases:
IOP Conference Series: Materials Science and Engineering, 2016
The article analyzes the deformations that are created in a circular plate with radial ribs locat... more The article analyzes the deformations that are created in a circular plate with radial ribs located on one side, under a concentrated force located at it's center, F =77000N. To this purpose the deflection obtained by analytically calculating is determined and compares with the displacement obtained by finite element method. To obtain the vertical displacements of a ribbed plate, the results of a similar plane plate, whose vertical displacements were determined, were used and displacements and tensions parameter value, as determined by the analytical method, were introduced.
The article analyzes the deformations that are created in a circular plate with radial ribs locat... more The article analyzes the deformations that are created in a circular plate with radial ribs located on one side, under a concentrated force located at it's center, F =77000N. To this purpose the deflection obtained by analytically calculating is determined and compares with the displacement obtained by finite element method. To obtain the vertical displacements of a ribbed plate, the results of a similar plane plate, whose vertical displacements were determined, were used and displacements and tensions parameter value, as determined by the analytical method, were introduced.
The Scientific Bulletin of "Valahia" University, Oct 1, 2022
Nanotechnology has a large area of applications, from devices to equipments from physics, enginee... more Nanotechnology has a large area of applications, from devices to equipments from physics, engineering, chemistry and biology. Nanostructures are used in materials engoineering, mecanics, synthesis, antifungic activity protocols and cultural heritage.
Scientific Bulletin of Valahia University - Materials and Mechanics
Inertial vibrating screens operating in resonance and post-resonance mode represent a class of sc... more Inertial vibrating screens operating in resonance and post-resonance mode represent a class of screens that present a series of advantages: simple construction and maintenance, high flow rates, low energy consumption, low level of vibrations transmitted to the building in which they are located, high screening efficiency. Due to these advantages, they tend to replace all other types of screens. However, these cisterns are very sensitive to variations in the supply flow, therefore they must be equipped with electronic control devices and automatic control of the supply flow with mineral aggregates. The present paper presents a numerical simulation of the variation of the vibration amplitudes for different values of the material on the screen using the professional calculation program MATHCAD 14.
Continuous beams are statically indeterminate systems (hyperstatic systems). New analytical metho... more Continuous beams are statically indeterminate systems (hyperstatic systems). New analytical methods based on matrix calculation are currently being used to solve such problems, which allow obtaining reactions. Using the MATHCAD professional program you can solve matrix equations and also you can get diagrams of variation of sectional efforts, displacements and rotations of sections along the entire length of the bar. This paper presents the matrix method for solving a particular problem of a beam located on seven prestressed elastic supports for compression.
In the engineering practice, knowing the technical condition of industrial equipment under operat... more In the engineering practice, knowing the technical condition of industrial equipment under operating shortening duration of the repair machinery, smart planning repairs to evolving wear while machine parts in motion, detecting and correcting errors in the installation or repair. They are some of the important objectives; maintenance engineer must follow to prevent damage to equipment and removing them permanently from operation and ensure repair costs as low as possible. The purpose of this paper is to present a case study on vibro-acoustical diagnosis of equipment and components subject to wear during operation to prevent damage to their catastrophic and the human and material losses.
Artificial muscles are likely to be essential components of robotics, and a variety of micro-mach... more Artificial muscles are likely to be essential components of robotics, and a variety of micro-machinery. The artificial muscles, have the potential to allow future robots to operate with superior muscle elasticity and isometric stress generation, even at extreme temperatures. Some new nanofibers for an artificial muscle is presented in this paper. The artificial muscle is based on a contractile polymer gel which undergoes abrupt volume changes in response to variations in external conditions. The tubes and wetting surfaces of the valves are constructed from teflon which is chemically inert and the fibers are made from Poly-Vinyl Alcohol PVA, alone or with PMMA and as magnetic polymer, with magnetite.
With quality control being an important issue in industry, there is a great need for free form su... more With quality control being an important issue in industry, there is a great need for free form surfaces measurements in manufacturing. With manufacturing processes becoming increasingly more flexible, there is also a demand for increasing flexibility of measuring machines. This paper describes the process of developing an automatic measurement system for any free-form surfaces. We present a system for 3D surfaces measurement with three inter-changeable measurement heads which can be easy mounted on its Z axis and allow contact or non-contact measurements. The paper presents also some considerations about error sources and system calibration. This system is developed under the project: „Researches on advanced control techniques based on the analysis of errors and three-dimensional modeling for a high precision measurement of the complex surfaces”funded by National Program Partnerships in Priority Areas.
The rotary drums are technological equipments used in manufacturing clinker cement materials, coo... more The rotary drums are technological equipments used in manufacturing clinker cement materials, cooling cement clinker, cooling burnt pyrites exhausted from roasting furnace lines of sulfuric acid, cooling alumina discharged from calcination ovens, cooling lime exhausted from lime ovens, cooling slag from chemical fertilizer furnaces, etc. Rotary drums are also used in mixing of powder or granular materials, separation and enrichment of ore, coal, etc.., washing ores and other minerals, crystallization and extraction of sugar from sugar beets, etc.., drying various raw materials for cement clinker, clay, marl, furnace slag, coal, grain, etc.. This paper presents some contributions of application using MATHCAD 14 program into design and verification of loose riding rings mounted on support blocks included in the equipment’s bearing group.
The project “ The Development of Education for the viability of labour market through the innovat... more The project “ The Development of Education for the viability of labour market through the innovative vectors: MECHATRONICS ‐ INTEGRONICS (M&I) ”, financed by the Sector Operational Programme Human Resources Romania 2007÷2013, responds to the directives of the Key Aria of Intervention 2.1 from the priority axis 2: Call for project proposal no. 90 ‐ Learn a trade, on: carrying out a wide set of activities for promoting the new HIGH-TECH ADVANCED field of MECHATRONICS & INTEGRONICS, on the internal labour market, especially in the ranks of university higher education graduates . This apex field is an integrative science that offers a wide perspective on the contribution of science and technology to the unfolding of the programmes corresponding to the national strategies for sustainable economic development and aligning to the ones promoted at the community level.
Scientific Bulletin of Valahia University - Materials and Mechanics, 2018
The implementation of proactive maintenance is a necessity required by the development of modern ... more The implementation of proactive maintenance is a necessity required by the development of modern technologies for the monitoring and exploitation of energy facilities and equipment. An important advantage of proactive maintenance is to permanently monitor the technical condition of the plant and equipment by vibration measurements and in the correct diagnosis in order to reasonably plan the required repairs. Turbo-aggregates are autonomous complex installations for producing electricity in refineries that operate in high power and high-speed modes. To monitor and control turbine vibrations, vibration sensors (uniaxial, biaxial and triaxial accelerometers) and proximity sensors (for relative displacements and lasers) are columned on bearing housings that transmit signals to data acquisition and processing systems as well is the Vibro-Expret diagnosis system presented in this paper.
Scientific Bulletin of Valahia University - Materials and Mechanics, 2017
One important objectives of proactive maintenance are the knowledge of the technical state of mac... more One important objectives of proactive maintenance are the knowledge of the technical state of machinery, the intelligent planning of interventions according to the diagnosis technique, identification and correction of assembling errors. The aim of this paper is to present a new case on the vibrations diagnosis of hydro-aggregate CAMPELA - CHE Dubasari (MOLDOVA). The VIBRO EXPERT diagnostic system used on the CAPMELA hydro-aggregate is designed to measure, monitor, diagnose, and analyze the technical and functional parameters in order to safe use of the hydro-aggregate turbine, using the vibrations data measurement. The proactive maintenance concept is being used more and more thanks to the development of these intelligent monitoring and control systems, in order to prevent interruptions due to major failures.
International Journal of Mechatronics and Applied Mechanics, 2018
Proactive maintenance is a relatively new concept used today by the exploitation of manufacturing... more Proactive maintenance is a relatively new concept used today by the exploitation of manufacturing and energy production systems consisting of vibro acoustic monitoring of installations and equipment with professional equipment, such as Expret-Vibro and PROFISIGNAL software. These vibration level measurements are required for vibro acoustic diagnosis and for timely programming of repairs that are being challenged before accidental malfunctions occur. Electric steam turbines are used to produce electrical energy in refineries, which are particularly complex and are equipped with a turbine shaft located on several sliding or rolling bearings. Vibration sensors are mounted on bearing housings and are formed from one-axial, biaxial and three-axial accelerometers for absolute magnitudes (P-P and RMS speeds) or laser proximal sensors (relative and offset displacements). These sensors transmit the signals of data acquisition cards and amplifiers for data processing
Scientific Bulletin of Valahia University - Materials and Mechanics, 2019
There is a direct analogy between the mechanical and electrical phenomena related to vibrations a... more There is a direct analogy between the mechanical and electrical phenomena related to vibrations and electromagnetic oscillations in the RLC series AC circuits and an inverse analogy to the electromagnetic oscillations in the RLC parallel alternative current (AC) circuits. Direct analogy RLC series AC circuit refers to the connection between complex velocity and complex electrical intensity, mechanical impedance and electrical impedance, etc. Reverse analogy RLC parallel AC circuits refers to the connection between complex velocity and complex electrical voltage, mechanical impedance and electrical admission, etc.
International Journal of Mechatronics and Applied Mechanics, 2017
Permanent knowledge of the technical state of rotating turbines, intelligent planning of interven... more Permanent knowledge of the technical state of rotating turbines, intelligent planning of interventions according to the evolution of vibrations parameters, identification and correction of mounting errors, are the important objectives of proactive maintenance that the operating engineer must pursue for avoidance disruptions or definitive decommissioning. The purpose of this paper is to present a case study on the vibrations diagnosis of hydro-aggregate CAMPELA HA1-CHE Dubasari/12 MW /120 RPM. The Vibro Expert diagnosis system mounted on CAPMELA is designed to measure, monitor, diagnose, predict and analyze the main technical and functional parameters of the hydro-aggregate in order to exploit it in maximum safety.
Scientific Bulletin of Valahia University - Materials and Mechanics, 2016
In the engineering practice, knowing the technical condition of industrial equipment under operat... more In the engineering practice, knowing the technical condition of industrial equipment under operating results shortening of repairs, repairs machinery to smart planning based on the time evolution of bearing wear, detect and correct errors on their installation or repair. This is one of the most important objectives of proactive maintenance; maintenance engineer must follow and monitor the wear of equipment with moving parts to prevent damage and removing them permanently from service, ensuring repair costs as low as possible. The aim of this paper is to present a particular case study on vibro- acoustic diagnosis of equipment and components subject to wear during operation to prevent catastrophic damage, as well as human and material losses.
Scientific Bulletin of Valahia University - Materials and Mechanics, 2017
According to the IWA norms, the water loss category includes also the apparent loss water due to ... more According to the IWA norms, the water loss category includes also the apparent loss water due to measurement errors of the water meters used at the connections. This paper presents the experimental results obtained during two years of registrations in TARGOVISTE’s Water Company network. A program for verifying the water meters used for connections has been implemented according to a statistical distribution, depending on the number of appliances and their dimensions. Using a theoretical simulation model, calibrated on the basis of the actual reference flows measured on the metrology approved measuring stand, a procedure was developed to assess the level of deviations in the fully metered water distribution network. Depending on the values of deviations and flows actually recorded by the meters in the distribution network, it was possible to estimate the percentage of the losses from the actually used water meters.
The actual graphical methods used by engineers when plotting the stress distributions are based o... more The actual graphical methods used by engineers when plotting the stress distributions are based on integrating the differential equations of stresses for each beam segment. The resulting integration constants are obtained by imposing boundary conditions for each beam segment. Using MATHCAD, this alternative proposed analytical method uses the step function Φ(x-a) which introduces a compact form of the stresses and displacements expressions. The constructive optimization is thus easier to be performed.
The authors have proposed to show the advantages of different specialized software that can used ... more The authors have proposed to show the advantages of different specialized software that can used in solving the algebraic and transcendental differential equations applied in mechanics, as problems of material point relative motion dynamics. Index Terms-dynamics, equations, software I. INTRODUCTION One considers the following problem: Inside a tube OA a material point M of mass m slides with friction (fig. 1). In the same time the tube is rotating with the angular velocity ω, around a vertical axis which intersects its ends. In this example the absolute and relative motion of the material point will be studied considering the following cases:
Uploads
Papers by cornel marin