Monica Iordache | University of Pitesti (original) (raw)

Papers by Monica Iordache

Research paper thumbnail of The Determination of the Dependency between the Input and Output Parameters in Fused Deposition Modeling (FDM) Using Multi Polytropic Functions

In the process of determination of the input-output correlations for FDM technology, researchers ... more In the process of determination of the input-output correlations for FDM technology, researchers usually consider polynomial or simple polytropic functions. For these functions the method of least squares leads to linear systems from which the unknowns are easily determined. The approximations given by polynomial and polytropic functions do not offer the possibility for the extrapolation of the results for other intermediate or extrapolated points, or the obtained results are very different comparing to the experimental ones. For these reasons in this paper we purpose the use of the multi polytropic functions, in which the polytropic exponents have real non-zero values. The obtained system from which the polytropic coefficients and exponents is no longer a linear one. Because of the convergence conditions of the Newton-Raphson method, this method is not a valid one for the solving of this system in the general case. The solving of the system is performed with the aid of the gradient...

Research paper thumbnail of Characteristics of Steels Joints Obtained by the FSW Process - A Brief Review

Key Engineering Materials, 2021

The FSW process has proven to be a promising process for joining steels and improving their chara... more The FSW process has proven to be a promising process for joining steels and improving their characteristics. However, the use of wrongs technological parameters leads to the appearance of defects. In this study, the macro and microstructural characteristics of steel joints and their mechanical properties are analyzed, and the main types of defects of the butt steel joints are presented. The main conclusions of the works studied are summarized and the main development directions for research on the characterization of steel structures joined by the FSW process are identified.

Research paper thumbnail of Numerical investigation of the radial cold rolling process of the grooves

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture

The radial cold rolling process is widely used in industry due to the advantages of chip removing... more The radial cold rolling process is widely used in industry due to the advantages of chip removing processing. In this study, circular complex profiles were formed by cold-rolling with radial feed, using a patented device with two roller-tools. By achieving several numerical simulations of the radial rolling process, the study aimed to establish the influence that the maximum set force and the diameter of the workpiece have on the productivity of the process and the quality of the formed trapezoidal and metric grooves. The numerical simulations were performed with ABAQUS/Explicit software and by using a previously validated finite element model. The penetration curve of the roller-tools in the material was introduced in the simulation as an analytical function and was determined based on experimental researches. To express the dependency of the penetration curve coefficients on other rolling conditions, a multivariable analysis using a design of experiments technique was performed. T...

Research paper thumbnail of A numerical strategy to identify the FSW process optimal parameters of a butt-welded joint of quasi-pure copper plates: modeling and experimental validation

The International Journal of Advanced Manufacturing Technology

Research paper thumbnail of State of Stresses Within U Bent Parts and Its Effect on the Springback Amount

Abstract: This paper presents the stresses distribution within U bent parts and its influence on ... more Abstract: This paper presents the stresses distribution within U bent parts and its influence on the amount of springback, when different blankholder forces and friction coefficients are used. The analysis was performed with the help of the ABAQUS software. It was found that greater stresses induced inside the part and a uniform distribution of them through the sheet thickness reduces the springback amount, increasing thus the part accuracy.

Research paper thumbnail of Analysis of Microstructure and Mechanical Properties of FSW Overlay Joints for Dissimilar Materials

DANIELA MONICA IORDACHE1*, EDUARD LAURENTIU NITU1, ADRIANA GABRIELA PLAIASU1*, LIA NICOLETA BOTIL... more DANIELA MONICA IORDACHE1*, EDUARD LAURENTIU NITU1, ADRIANA GABRIELA PLAIASU1*, LIA NICOLETA BOTILA2, MARIAN CATALIN DUCU1*, MARIA MINODORA PASARE3 1University of Pitesti, Department of Manufacturing and Industrial Management, 1 Tg. Vale Str.1, 110040, Pitesti, Romania 2National Research & Development Institute for Welding and Material Testing ISIM, 30 Mihai Viteazul Av., 300222, Timisoara, Romania 3 University Constantin Brâncusi of Targu Jiu, Department of Engineering and Management of Technological Systems, 30 Geneva Str., 210135, Targu Jiu, Romania

Research paper thumbnail of A New Approach to Optimize the Relative Clearance for Cylindrical Joints Manufactured by FDM 3D Printing Using a Hybrid Genetic Algorithm Artificial Neural Network and Rational Function

Nowadays, FDM technology permits obtaining functional prototypes or even end parts. The process p... more Nowadays, FDM technology permits obtaining functional prototypes or even end parts. The process parameters, such as layer thickness, building orientation, fill density, type of support, etc., have great influence on the quality, functionality and behavior of the obtained parts during their lifetime. In this paper, we present a study concerning the possibilities of obtaining certain values for clearance in revolute joints of non-assembly mechanisms manufactured by FDM 3D Printing. To ensure the functioning of the assembly, one must know the relationship between the imposed and measured clearances by taking into account the significant input data. One way is to use the automat learning method with an artificial neuronal network (ANN). The data necessary for the training, testing, and validation of ANN were experimentally obtained, using a complete L 27 Taguchi experimental plan. A total of 27 samples were printed with different values of the following parameters: the infill density, t...

Research paper thumbnail of Friction Stir Welding of Steel Structures - A Brief Review

Key Engineering Materials, 2021

Friction stir welding is a relatively new technique, developed in 1991, which, due to its advanta... more Friction stir welding is a relatively new technique, developed in 1991, which, due to its advantages, has been continuously developed and applied to industrial applications. This process of joining materials in solid state is an extremely complex one because of the physical phenomena that occur during the process, which makes the research still in full development. The paper presents an analysis of recent scientific work on the use of the FSW process for the joining of steel structures. Thus, the types of steels and merged structures, the processes used and the technological parameters used are analyzed. On the basis of this analysis, the main conclusions of the studied works are summarized and the main development directions for research on the FSW process of steel structures are identified.

Research paper thumbnail of Comparative study on microhardness between friction stir welding and tungsten inert gas assisted friction stir welding of pure copper

MATEC Web of Conferences

Welding copper and its alloys is usually difficult to achieve by conventional fusion welding proc... more Welding copper and its alloys is usually difficult to achieve by conventional fusion welding processes because of high thermal diffusivity of copper, which is at least 10 times higher than most steel alloys. In order to reduce the increased temperature loss, it would be advantageous to use a process that is carried out at lower temperatures. Friction Stir Welding (FSW) is a solid state joining process that involves the joining of two metal pieces at the molecular level without melting and was explored as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (TIG - tungsten inert gas) which generates and adds heat to the process. The research includes two experiments for the FSW process and two experiments for TIG assisted FSW process. It is presented the evolution of the temperature and of the axial force during the process and is determined the microhardness for each experimental case. The ai...

Research paper thumbnail of Orientation of process parameter values of TIG assisted FSW of copper to obtain improved mechanical properties

IOP Conference Series: Materials Science and Engineering

Research paper thumbnail of Microstructure and Properties of Copper and 5754 Aluminum Alloy Joints by Friction Stir Welding

Revista de Chimie

Welding dissimilar materials aluminum and copper by FSW are of great interest because Al and Cu a... more Welding dissimilar materials aluminum and copper by FSW are of great interest because Al and Cu are two most common engineering materials widely used in many industries. The paper analyzes the microstructure and mechanical properties obtained by butt of dissimilar material Cu - Al alloys (EN-AW-5754) by FSW. The joining by FSW process of the two samples (5 mm thickness) was performed with the pin of the tool tangential to copper plate. The values of the process parameters were the same in both cases: the rotation speed of the pin 1200 [rpm] and feed rate 60 [mm / min]. The microstructure was examined in 6 zones covering the whole thickness of the plates, Vickers microhardness was measured along a perpendicular line to the nugget and residual stresses.

Research paper thumbnail of Optimizing the construction of devices to control inaccesible surfaces - case study

IOP Conference Series: Materials Science and Engineering

The modern concept for the evolution of manufacturing systems requires multi-criteria optimizatio... more The modern concept for the evolution of manufacturing systems requires multi-criteria optimization of technological processes and equipments, prioritizing associated criteria according to their importance. Technological preparation of the manufacturing can be developed, depending on the volume of production, to the limit of favourable economical effects related to the recovery of the costs for the design and execution of the technological equipment. Devices, as subsystems of the technological system, in the general context of modernization and diversification of machines, tools, semi-finished products and drives, are made in a multitude of constructive variants, which in many cases do not allow their identification, study and improvement. This paper presents a case study in which the multi-criteria analysis of some structures, based on a general optimization method, of novelty character, is used in order to determine the optimal construction variant of a control device. The rational construction of the control device confirms that the optimization method and the proposed calculation methods are correct and determine a different system configuration, new features and functions, and a specific method of working to control inaccessible surfaces.

Research paper thumbnail of Method of Optimizing the Construction of Machining, Assembly and Control Devices

IOP Conference Series: Materials Science and Engineering

Industry dynamics, driven by economic and social requirements, must generate more interest in tec... more Industry dynamics, driven by economic and social requirements, must generate more interest in technological optimization, capable of ensuring a steady development of advanced technical means to equip machining processes. For these reasons, the development of tools, devices, work equipment and control, as well as the modernization of machine tools, is the certain solution to modernize production systems that require considerable time and effort. This type of approach is also related to our theoretical, experimental and industrial applications of recent years, presented in this paper, which have as main objectives the elaboration and use of mathematical models, new calculation methods, optimization algorithms, new processing and control methods, as well as some structures for the construction and configuration of technological equipment with a high level of performance and substantially reduced costs.

Research paper thumbnail of Experimental investigations of tungsten inert gas assisted friction stir welding of pure copper plates

IOP Conference Series: Materials Science and Engineering

Welding copper and its alloys is usually difficult to join by conventional fusion welding process... more Welding copper and its alloys is usually difficult to join by conventional fusion welding processes because of high thermal diffusivity of the copper, alloying elements, necessity of using a shielding gas and a clean surface. To overcome this inconvenience, Friction Stir Welding (FSW), a solid state joining process that relies on frictional heating and plastic deformation, is used as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (WIG) which generates and adds heat to the process. The aim of this paper is to identify the influence of the additional heat on the process parameters and on the welding joint properties (distribution of the temperature, hardness and roughness). The research includes two experiments for the FSW process and one experiment for tungsten inert gas assisted FSW process. The outcomes of the investigation are compared and analysed for both welding variants. Adding a supplementary heat source, the plates are preheated and are obtain some advantages such as reduced forces used in process and FSW tool wear, faster and better plasticization of the material, increased welding speed and a proper weld quality.

Research paper thumbnail of Studies regarding the influence of the design parameters on the shock behaviour of the parts obtained by 3D Printing technology

University of Pitesti. Scientific Bulletin - Automotive Series

Over the last decade, more and more parts are manufactured by 3D Printing. This is a printing tec... more Over the last decade, more and more parts are manufactured by 3D Printing. This is a printing technology-LPD (Layer Plastic Deposition) being a precise technology for applying the material in order to obtain detailed and accurate prints. This paper presents the bending behavior of the parts obtained by the rapid 3D prototyping technology. 3D printed parts often have anisotropic mechanical properties, more precisely low mechanical properties in the Z axis direction. To this end, 3D models of test samples with different internal structures, orientations and different dimensions of the geometric shapes that make up these internal structures have been made. The material from which the specimens were made is Z-ULTRAT.

Research paper thumbnail of Developing structures for the construction of the processing equipment - Case study

IOP Conference Series: Materials Science and Engineering

The evolution of the manufacturing processes requires, as a mandatory condition, to increase the ... more The evolution of the manufacturing processes requires, as a mandatory condition, to increase the performance of the technological equipment for processing, assembling and control, by promoting new solutions in the field of devices of the semi-finished products, but also by developing special or modular multifunctional components for the modernization of machine tools. This paper proposes a method of optimization of the technological process and equipment, which in the first stage determines, on the basis of a technological chart, the optimal sequence and the number of operations or phases of processing, and in the second step with the global utility method, the optimal combination of special or modular structures, from existing or new ones, is determined for the construction and configuration of a flexible multislot machine for simultaneous and successive centring and spherical operation. We believe that the creation of tools, devices for orientation and fixing, tooling, support, gu...

Research paper thumbnail of Friction Stir Welding of three dissimilar aluminium alloy used in aeronautics industry

IOP Conference Series: Materials Science and Engineering

Friction Stir Welding (FSW) is an innovative solid-state joining process. This process was, in fi... more Friction Stir Welding (FSW) is an innovative solid-state joining process. This process was, in first time, develop to join the similar aluminum plates but now the technology can be used to weld a large area of materials similar or dissimilar. Taking these into account FSW process, for dissimilar materials are increasingly required, more than traditional arc welding, in industrial environment. More than that FSW is used in aeronautics industry because of very good result and very good weldability between aluminum alloy used at building of airplanes, where the body of airplane are 20% aluminum alloy and this percent can be increaser in future. In this paper is presented an experimental study which includes welding three dissimilar aluminum alloy, with different properties, used in aeronautics industry, this materials are: AA 2024, AA6061 and AA7075. After welding with different parameters, the welding join and welding process will be analyzed considering process temperature, process vertical force, and roughnessof welding seams, visual aspect and microhardness.

Research paper thumbnail of Numerical Simulation of Friction Stir Welding (FSW) Process Based on ABAQUS Environment

Solid State Phenomena, 2016

. Simulation of the FSW process is a complex issue, as it implies interactions between thermal an... more . Simulation of the FSW process is a complex issue, as it implies interactions between thermal and mechanical phenomena and the quality of the welding depends on many factors. In order to reduce the time of the experimental tests, which can be long and expensive, numerical simulation of the FSW process has been tried during the last ten years. However, there still remain aspects that cannot be completely simulated. In this paper the authors present the steps of the numerical simulation using the finite elements method, in order to evaluate the boundary conditions of the model and the geometry of the tools by using the Arbitrary Lagrangian Eulerian (ALE) adaptive mesh controls.

Research paper thumbnail of Evaluation of Thermal Distribution in Friction Stir Welding on Dissimilar Materials (Cu-Al) Using Infrared Thermography and Numerical Simulation

Advanced Materials Research, 2016

Friction Stir Welding (FSW) is a solid state joining process realized by the interaction between ... more Friction Stir Welding (FSW) is a solid state joining process realized by the interaction between a non-consumable welding tool that rotates on the contact surfaces of the combined parts. Welding dissimilar materials aluminum and copper by FSW are of great interest because Al and Cu are two most common engineering materials widely used in many industries. This paper presents an investigation concerning the influence of the rotation of the tool on temperatures during the welding process. Also, the welding of copper and aluminum materials by FSW process was simulated using a finite element model. Three-dimensional FE model has been developed in ABAQUS/Explicit using the Coupled Eulerian Lagrangian method, the Johnson–Cook material law and the Coulomb’s Law of friction and was validated by infrared thermography method and thermocouple measurement.

Research paper thumbnail of Numerical Simulation of Friction Stir Welding of Aluminum Alloys: A Brief Review

Applied Mechanics and Materials, 2015

Friction Stir Welding (FSW) is the latest innovative and most complex process which is widely app... more Friction Stir Welding (FSW) is the latest innovative and most complex process which is widely applied to the welding of lightweight alloys, such as aluminum and magnesium alloys, and most recently, titanium alloys, copper alloys, steels and super-alloys. Friction stir welding is a highly complex process comprising several highly coupled physical phenomena. The experiments are often time consuming and costly. To overcome these problems, numerical analysis has frequently been used in the last ten years. In this paper is presented a brief review of scientific papers in recent years on numerical simulation of Friction Stir Welding of aluminum alloys. The main elements analyzed by FSW simulation, and briefly in this paper are: temperature and residual stress distribution; work tool geometry (size and shape of the pin); distribution of equivalent plastic deformation; main areas resulted after welding; distribution of microstructure (grain size); parameters and optimization of the FSW proc...

Research paper thumbnail of The Determination of the Dependency between the Input and Output Parameters in Fused Deposition Modeling (FDM) Using Multi Polytropic Functions

In the process of determination of the input-output correlations for FDM technology, researchers ... more In the process of determination of the input-output correlations for FDM technology, researchers usually consider polynomial or simple polytropic functions. For these functions the method of least squares leads to linear systems from which the unknowns are easily determined. The approximations given by polynomial and polytropic functions do not offer the possibility for the extrapolation of the results for other intermediate or extrapolated points, or the obtained results are very different comparing to the experimental ones. For these reasons in this paper we purpose the use of the multi polytropic functions, in which the polytropic exponents have real non-zero values. The obtained system from which the polytropic coefficients and exponents is no longer a linear one. Because of the convergence conditions of the Newton-Raphson method, this method is not a valid one for the solving of this system in the general case. The solving of the system is performed with the aid of the gradient...

Research paper thumbnail of Characteristics of Steels Joints Obtained by the FSW Process - A Brief Review

Key Engineering Materials, 2021

The FSW process has proven to be a promising process for joining steels and improving their chara... more The FSW process has proven to be a promising process for joining steels and improving their characteristics. However, the use of wrongs technological parameters leads to the appearance of defects. In this study, the macro and microstructural characteristics of steel joints and their mechanical properties are analyzed, and the main types of defects of the butt steel joints are presented. The main conclusions of the works studied are summarized and the main development directions for research on the characterization of steel structures joined by the FSW process are identified.

Research paper thumbnail of Numerical investigation of the radial cold rolling process of the grooves

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture

The radial cold rolling process is widely used in industry due to the advantages of chip removing... more The radial cold rolling process is widely used in industry due to the advantages of chip removing processing. In this study, circular complex profiles were formed by cold-rolling with radial feed, using a patented device with two roller-tools. By achieving several numerical simulations of the radial rolling process, the study aimed to establish the influence that the maximum set force and the diameter of the workpiece have on the productivity of the process and the quality of the formed trapezoidal and metric grooves. The numerical simulations were performed with ABAQUS/Explicit software and by using a previously validated finite element model. The penetration curve of the roller-tools in the material was introduced in the simulation as an analytical function and was determined based on experimental researches. To express the dependency of the penetration curve coefficients on other rolling conditions, a multivariable analysis using a design of experiments technique was performed. T...

Research paper thumbnail of A numerical strategy to identify the FSW process optimal parameters of a butt-welded joint of quasi-pure copper plates: modeling and experimental validation

The International Journal of Advanced Manufacturing Technology

Research paper thumbnail of State of Stresses Within U Bent Parts and Its Effect on the Springback Amount

Abstract: This paper presents the stresses distribution within U bent parts and its influence on ... more Abstract: This paper presents the stresses distribution within U bent parts and its influence on the amount of springback, when different blankholder forces and friction coefficients are used. The analysis was performed with the help of the ABAQUS software. It was found that greater stresses induced inside the part and a uniform distribution of them through the sheet thickness reduces the springback amount, increasing thus the part accuracy.

Research paper thumbnail of Analysis of Microstructure and Mechanical Properties of FSW Overlay Joints for Dissimilar Materials

DANIELA MONICA IORDACHE1*, EDUARD LAURENTIU NITU1, ADRIANA GABRIELA PLAIASU1*, LIA NICOLETA BOTIL... more DANIELA MONICA IORDACHE1*, EDUARD LAURENTIU NITU1, ADRIANA GABRIELA PLAIASU1*, LIA NICOLETA BOTILA2, MARIAN CATALIN DUCU1*, MARIA MINODORA PASARE3 1University of Pitesti, Department of Manufacturing and Industrial Management, 1 Tg. Vale Str.1, 110040, Pitesti, Romania 2National Research & Development Institute for Welding and Material Testing ISIM, 30 Mihai Viteazul Av., 300222, Timisoara, Romania 3 University Constantin Brâncusi of Targu Jiu, Department of Engineering and Management of Technological Systems, 30 Geneva Str., 210135, Targu Jiu, Romania

Research paper thumbnail of A New Approach to Optimize the Relative Clearance for Cylindrical Joints Manufactured by FDM 3D Printing Using a Hybrid Genetic Algorithm Artificial Neural Network and Rational Function

Nowadays, FDM technology permits obtaining functional prototypes or even end parts. The process p... more Nowadays, FDM technology permits obtaining functional prototypes or even end parts. The process parameters, such as layer thickness, building orientation, fill density, type of support, etc., have great influence on the quality, functionality and behavior of the obtained parts during their lifetime. In this paper, we present a study concerning the possibilities of obtaining certain values for clearance in revolute joints of non-assembly mechanisms manufactured by FDM 3D Printing. To ensure the functioning of the assembly, one must know the relationship between the imposed and measured clearances by taking into account the significant input data. One way is to use the automat learning method with an artificial neuronal network (ANN). The data necessary for the training, testing, and validation of ANN were experimentally obtained, using a complete L 27 Taguchi experimental plan. A total of 27 samples were printed with different values of the following parameters: the infill density, t...

Research paper thumbnail of Friction Stir Welding of Steel Structures - A Brief Review

Key Engineering Materials, 2021

Friction stir welding is a relatively new technique, developed in 1991, which, due to its advanta... more Friction stir welding is a relatively new technique, developed in 1991, which, due to its advantages, has been continuously developed and applied to industrial applications. This process of joining materials in solid state is an extremely complex one because of the physical phenomena that occur during the process, which makes the research still in full development. The paper presents an analysis of recent scientific work on the use of the FSW process for the joining of steel structures. Thus, the types of steels and merged structures, the processes used and the technological parameters used are analyzed. On the basis of this analysis, the main conclusions of the studied works are summarized and the main development directions for research on the FSW process of steel structures are identified.

Research paper thumbnail of Comparative study on microhardness between friction stir welding and tungsten inert gas assisted friction stir welding of pure copper

MATEC Web of Conferences

Welding copper and its alloys is usually difficult to achieve by conventional fusion welding proc... more Welding copper and its alloys is usually difficult to achieve by conventional fusion welding processes because of high thermal diffusivity of copper, which is at least 10 times higher than most steel alloys. In order to reduce the increased temperature loss, it would be advantageous to use a process that is carried out at lower temperatures. Friction Stir Welding (FSW) is a solid state joining process that involves the joining of two metal pieces at the molecular level without melting and was explored as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (TIG - tungsten inert gas) which generates and adds heat to the process. The research includes two experiments for the FSW process and two experiments for TIG assisted FSW process. It is presented the evolution of the temperature and of the axial force during the process and is determined the microhardness for each experimental case. The ai...

Research paper thumbnail of Orientation of process parameter values of TIG assisted FSW of copper to obtain improved mechanical properties

IOP Conference Series: Materials Science and Engineering

Research paper thumbnail of Microstructure and Properties of Copper and 5754 Aluminum Alloy Joints by Friction Stir Welding

Revista de Chimie

Welding dissimilar materials aluminum and copper by FSW are of great interest because Al and Cu a... more Welding dissimilar materials aluminum and copper by FSW are of great interest because Al and Cu are two most common engineering materials widely used in many industries. The paper analyzes the microstructure and mechanical properties obtained by butt of dissimilar material Cu - Al alloys (EN-AW-5754) by FSW. The joining by FSW process of the two samples (5 mm thickness) was performed with the pin of the tool tangential to copper plate. The values of the process parameters were the same in both cases: the rotation speed of the pin 1200 [rpm] and feed rate 60 [mm / min]. The microstructure was examined in 6 zones covering the whole thickness of the plates, Vickers microhardness was measured along a perpendicular line to the nugget and residual stresses.

Research paper thumbnail of Optimizing the construction of devices to control inaccesible surfaces - case study

IOP Conference Series: Materials Science and Engineering

The modern concept for the evolution of manufacturing systems requires multi-criteria optimizatio... more The modern concept for the evolution of manufacturing systems requires multi-criteria optimization of technological processes and equipments, prioritizing associated criteria according to their importance. Technological preparation of the manufacturing can be developed, depending on the volume of production, to the limit of favourable economical effects related to the recovery of the costs for the design and execution of the technological equipment. Devices, as subsystems of the technological system, in the general context of modernization and diversification of machines, tools, semi-finished products and drives, are made in a multitude of constructive variants, which in many cases do not allow their identification, study and improvement. This paper presents a case study in which the multi-criteria analysis of some structures, based on a general optimization method, of novelty character, is used in order to determine the optimal construction variant of a control device. The rational construction of the control device confirms that the optimization method and the proposed calculation methods are correct and determine a different system configuration, new features and functions, and a specific method of working to control inaccessible surfaces.

Research paper thumbnail of Method of Optimizing the Construction of Machining, Assembly and Control Devices

IOP Conference Series: Materials Science and Engineering

Industry dynamics, driven by economic and social requirements, must generate more interest in tec... more Industry dynamics, driven by economic and social requirements, must generate more interest in technological optimization, capable of ensuring a steady development of advanced technical means to equip machining processes. For these reasons, the development of tools, devices, work equipment and control, as well as the modernization of machine tools, is the certain solution to modernize production systems that require considerable time and effort. This type of approach is also related to our theoretical, experimental and industrial applications of recent years, presented in this paper, which have as main objectives the elaboration and use of mathematical models, new calculation methods, optimization algorithms, new processing and control methods, as well as some structures for the construction and configuration of technological equipment with a high level of performance and substantially reduced costs.

Research paper thumbnail of Experimental investigations of tungsten inert gas assisted friction stir welding of pure copper plates

IOP Conference Series: Materials Science and Engineering

Welding copper and its alloys is usually difficult to join by conventional fusion welding process... more Welding copper and its alloys is usually difficult to join by conventional fusion welding processes because of high thermal diffusivity of the copper, alloying elements, necessity of using a shielding gas and a clean surface. To overcome this inconvenience, Friction Stir Welding (FSW), a solid state joining process that relies on frictional heating and plastic deformation, is used as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (WIG) which generates and adds heat to the process. The aim of this paper is to identify the influence of the additional heat on the process parameters and on the welding joint properties (distribution of the temperature, hardness and roughness). The research includes two experiments for the FSW process and one experiment for tungsten inert gas assisted FSW process. The outcomes of the investigation are compared and analysed for both welding variants. Adding a supplementary heat source, the plates are preheated and are obtain some advantages such as reduced forces used in process and FSW tool wear, faster and better plasticization of the material, increased welding speed and a proper weld quality.

Research paper thumbnail of Studies regarding the influence of the design parameters on the shock behaviour of the parts obtained by 3D Printing technology

University of Pitesti. Scientific Bulletin - Automotive Series

Over the last decade, more and more parts are manufactured by 3D Printing. This is a printing tec... more Over the last decade, more and more parts are manufactured by 3D Printing. This is a printing technology-LPD (Layer Plastic Deposition) being a precise technology for applying the material in order to obtain detailed and accurate prints. This paper presents the bending behavior of the parts obtained by the rapid 3D prototyping technology. 3D printed parts often have anisotropic mechanical properties, more precisely low mechanical properties in the Z axis direction. To this end, 3D models of test samples with different internal structures, orientations and different dimensions of the geometric shapes that make up these internal structures have been made. The material from which the specimens were made is Z-ULTRAT.

Research paper thumbnail of Developing structures for the construction of the processing equipment - Case study

IOP Conference Series: Materials Science and Engineering

The evolution of the manufacturing processes requires, as a mandatory condition, to increase the ... more The evolution of the manufacturing processes requires, as a mandatory condition, to increase the performance of the technological equipment for processing, assembling and control, by promoting new solutions in the field of devices of the semi-finished products, but also by developing special or modular multifunctional components for the modernization of machine tools. This paper proposes a method of optimization of the technological process and equipment, which in the first stage determines, on the basis of a technological chart, the optimal sequence and the number of operations or phases of processing, and in the second step with the global utility method, the optimal combination of special or modular structures, from existing or new ones, is determined for the construction and configuration of a flexible multislot machine for simultaneous and successive centring and spherical operation. We believe that the creation of tools, devices for orientation and fixing, tooling, support, gu...

Research paper thumbnail of Friction Stir Welding of three dissimilar aluminium alloy used in aeronautics industry

IOP Conference Series: Materials Science and Engineering

Friction Stir Welding (FSW) is an innovative solid-state joining process. This process was, in fi... more Friction Stir Welding (FSW) is an innovative solid-state joining process. This process was, in first time, develop to join the similar aluminum plates but now the technology can be used to weld a large area of materials similar or dissimilar. Taking these into account FSW process, for dissimilar materials are increasingly required, more than traditional arc welding, in industrial environment. More than that FSW is used in aeronautics industry because of very good result and very good weldability between aluminum alloy used at building of airplanes, where the body of airplane are 20% aluminum alloy and this percent can be increaser in future. In this paper is presented an experimental study which includes welding three dissimilar aluminum alloy, with different properties, used in aeronautics industry, this materials are: AA 2024, AA6061 and AA7075. After welding with different parameters, the welding join and welding process will be analyzed considering process temperature, process vertical force, and roughnessof welding seams, visual aspect and microhardness.

Research paper thumbnail of Numerical Simulation of Friction Stir Welding (FSW) Process Based on ABAQUS Environment

Solid State Phenomena, 2016

. Simulation of the FSW process is a complex issue, as it implies interactions between thermal an... more . Simulation of the FSW process is a complex issue, as it implies interactions between thermal and mechanical phenomena and the quality of the welding depends on many factors. In order to reduce the time of the experimental tests, which can be long and expensive, numerical simulation of the FSW process has been tried during the last ten years. However, there still remain aspects that cannot be completely simulated. In this paper the authors present the steps of the numerical simulation using the finite elements method, in order to evaluate the boundary conditions of the model and the geometry of the tools by using the Arbitrary Lagrangian Eulerian (ALE) adaptive mesh controls.

Research paper thumbnail of Evaluation of Thermal Distribution in Friction Stir Welding on Dissimilar Materials (Cu-Al) Using Infrared Thermography and Numerical Simulation

Advanced Materials Research, 2016

Friction Stir Welding (FSW) is a solid state joining process realized by the interaction between ... more Friction Stir Welding (FSW) is a solid state joining process realized by the interaction between a non-consumable welding tool that rotates on the contact surfaces of the combined parts. Welding dissimilar materials aluminum and copper by FSW are of great interest because Al and Cu are two most common engineering materials widely used in many industries. This paper presents an investigation concerning the influence of the rotation of the tool on temperatures during the welding process. Also, the welding of copper and aluminum materials by FSW process was simulated using a finite element model. Three-dimensional FE model has been developed in ABAQUS/Explicit using the Coupled Eulerian Lagrangian method, the Johnson–Cook material law and the Coulomb’s Law of friction and was validated by infrared thermography method and thermocouple measurement.

Research paper thumbnail of Numerical Simulation of Friction Stir Welding of Aluminum Alloys: A Brief Review

Applied Mechanics and Materials, 2015

Friction Stir Welding (FSW) is the latest innovative and most complex process which is widely app... more Friction Stir Welding (FSW) is the latest innovative and most complex process which is widely applied to the welding of lightweight alloys, such as aluminum and magnesium alloys, and most recently, titanium alloys, copper alloys, steels and super-alloys. Friction stir welding is a highly complex process comprising several highly coupled physical phenomena. The experiments are often time consuming and costly. To overcome these problems, numerical analysis has frequently been used in the last ten years. In this paper is presented a brief review of scientific papers in recent years on numerical simulation of Friction Stir Welding of aluminum alloys. The main elements analyzed by FSW simulation, and briefly in this paper are: temperature and residual stress distribution; work tool geometry (size and shape of the pin); distribution of equivalent plastic deformation; main areas resulted after welding; distribution of microstructure (grain size); parameters and optimization of the FSW proc...