Mechanical tests were performed on samples prepared from the body and the neck of bottles made of... more Mechanical tests were performed on samples prepared from the body and the neck of bottles made of seamless tube, steel 34CrMo4. Plastic material flow curves were taken from tensile tests on samples which were made from tubes and finished bottles. Deformation hardening intensity is calculated, and propensity towards brittle fracture is estimated on the basis of the ratio of total elongation and elongation at maximum load. Compared to the samples of quenched and tempered bottle body, quenched and tempered bottle neck samples indicate that characteristics of strength are almost unchanged with an increase in the minimum strain at the destruction from 12,8% to 15,1%. It was concluded that the results of the plastic material flow can serve as a preliminary indication of anomalies that could contribute to unsatisfactory results of the burst test.
In this paper an approach for multi-criteria analysis of laser cut surface characteristics using ... more In this paper an approach for multi-criteria analysis of laser cut surface characteristics using multi-criteria decision making (MCDM) approach was presented. Laser cutting experiment was conducted based on Taguchi's L27 experimental design by varying laser power, cutting speed, assist gas pressure and focus position at three levels. Multi-criteria analysis was performed by using the weighted aggregated sum product assessment (WASPAS) method while considering burr height, drag line separation, depth of separation line, surface roughness and perpendicularity of the cut as assessment criteria. Based on conducted experimental investigation the MCDM model with 27 alternatives (laser cuts) and five criteria was developed. The relative importance of criteria was determined by using pairwise comparison matrix and geometric mean method of the analytic hierarchy process (AHP) method.
DOAJ (DOAJ: Directory of Open Access Journals), Dec 1, 2016
Today highly competitive market and demands for obtain high surface finish and machining of compl... more Today highly competitive market and demands for obtain high surface finish and machining of complex shape geometries replace conventional machining processes with non-conventional. Plasma jet cutting is one of these non-conventional processes that primary uses a thermal energy of highly ionized gas to cut specified material and blow molten metal away. Main advantages of plasma jet cutting process are high speed of cutting, cutting different types of materials, the quality of cut and moderate to low investment costs. This paper presents experimental results concerning the surface roughness variation at plasma jet cutting of structural steel S235JRG2 plate thickness of 15 mm. Using the experimental data artificial neural network (ANN) model was developed in order to predict the surface roughness in terms of two input parameters, cutting current and cutting speed. After the prediction accuracy of the developed model was validated, the model was used for analyzing influence of input parameters on process response values.
This paper presents a systematic methodology for empirical modeling and optimization of surface r... more This paper presents a systematic methodology for empirical modeling and optimization of surface roughness in CO 2 laser nitrogen cutting of stainless steel. The surface roughness prediction model was developed in terms of laser power, cutting speed, assist gas pressure and focus position by using the artificial neural network (ANN). To cover a wider range of laser cutting parameters and obtain an experimental database for the ANN model development, Taguchi's L 27 orthogonal array was implemented in the experimental plan. The developed ANN model was expressed as an explicit nonlinear function, while the influence of laser cutting parameters and their interactions on surface roughness were analyzed by generating 2D and 3D plots. The final goal of the experimental study focuses on the determination of the optimal laser cutting parameters for the minimization of surface roughness. Since the solution space of the developed ANN model is complex, and the possibility of many local solutions is great, simulated annealing (SA) was selected as a method for the optimization of surface roughness.
Machining of aluminum and its alloys requires the use of cutting tools with special geometry and ... more Machining of aluminum and its alloys requires the use of cutting tools with special geometry and material. Since there exists a number of cutting tools for aluminum machining, each with unique characteristics, selection of the most appropriate cutting tool for a given application is very complex task which can be viewed as a multi-criteria decision making (MCDM) problem. This paper is focused on multi-criteria analysis of VCGT cutting inserts for aluminum alloys turning by applying recently developed MCDM method, i.e. weighted aggregated sum product assessment (WASPAS) method. The MCDM model was defined using the available catalogue data from cutting tool manufacturers.
Heat affected zone (HAZ) of the laser cutting process may be developed based on combination of di... more Heat affected zone (HAZ) of the laser cutting process may be developed based on combination of different factors. In this investigation the HAZ forecasting, based on the different laser cutting parameters, was analyzed. The main goal was to predict the HAZ according to three inputs. The purpose of this research was to develop and apply the Extreme Learning Machine (ELM) to predict the HAZ. The ELM results were compared with genetic programming (GP) and artificial neural network (ANN). The reliability of the computational models were accessed based on simulation results and by using several statistical indicators. Based upon simulation results, it was demonstrated that ELM can be utilized effectively in applications of HAZ forecasting.
Solar energy is very important alternative energy due to the vase deposit. The main goal of the s... more Solar energy is very important alternative energy due to the vase deposit. The main goal of the study was to analyze the solar radiation based on the four parameters: mean sea level (MSL), dry-bulb temperature (DBT), wet-bulb temperature (WBT) and relative humidity (RH). Adaptive neuro-fuzzy inference system (ANFIS) was used in order to estimate the parameters influence on the solar radiation prediction. Variable selection process was used to select the most dominant factors which affect the solar radiation prediction. The results shown that the DBT and RH are the most dominant factors for the solar radiation prediction.
Bimetallic materials are construction materials that are increasingly used in many industries: in... more Bimetallic materials are construction materials that are increasingly used in many industries: in the graphic industry, tobacco processing industry for various cutting knives, in the chemical industry for various plants and vessels, food industry, military industry, etc. In the production of ships, their use becomes dominant, primarily as a combination of cheap construction materials highly resistant to corrosion, at a price closer to construction materials. The appearance of plating with the help of explosion energy has significantly increased the range and quality of available multilayer metals. Although stainless steels and aluminum are the most commonly used material for bimetallic and clad materials, materials such as titanium, zirconium or tantalum are increasingly used. The paper analyzes the process of explosion welding and the results of exploration of the explosion of a welded joint of copper and brass. The microhardness of the material in the welded joint, tribological characteristics and scratch test joint were analyzed.
The last two decades have seen a dramatic shift in use of technology to drive improvements in man... more The last two decades have seen a dramatic shift in use of technology to drive improvements in manufacturing operations. Just twenty years ago, many small and mid-size manufacturers relied on paper-based systems to run their businesses. The application of advanced technologies in manufacturing such as nanotechnology, cloud computing, the Internet of Things (IoT) are changing the face of manufacturing in ways unimaginable a few decades ago. In addition to cutting the costs, these technologies create speed, precision, efficiency and flexibility for manufacturing companies. Technologies that have the greatest impact include cloud, mobile, big data and analytics, internet of things (IoT), robotics, cognitive computing/artificial intelligence (AI), 3D printing, augmented reality/virtual reality (AR/VR), and even blockchain. In the paper is presented top 10 strategic technology trends for 2012 to 2019 that the every year compani Gartner, Inc. from the IT Symposium/Xpo stage, we unveil our for the following year that CIOs and other senior executives should be paying attention to.
In the paper examined was the influence of the cutting regime parameters on surface roughness par... more In the paper examined was the influence of the cutting regime parameters on surface roughness parameters during turning of hard steel with cubic boron nitrite cutting insert. In this study for modeling of surface finish parameters was used central compositional design of experiment and artificial neural network. The values of surface roughness parameters Ra and Rt were predicted by this two-modeling methodology and determined models were then compared. The results showed that the proposed systems can significantly increase the accuracy of the product profile when compared to the conventional approaches. The results indicate that the design of experiments with central composition plan modeling technique and artificial neural network can be effectively used for the prediction of the surface roughness for hard steel and determined significand cutting regime parameters.
Dross height is an important cut quality characteristic in plasma jet cutting process. It can be ... more Dross height is an important cut quality characteristic in plasma jet cutting process. It can be defined as molten metal blown from the cutting zone and localized on the bottom of the metal sheet. In each plasma jet cutting process, it is important to obtain dross free cuts. Aluminium is as material very present in shipbuilding and metal industry and because of that very usually cut by plasma jet. Because of high heat and electrical conductivity of aluminium, plasma jet cutting is followed by insecurity about process parameters settings that lead to optimal cut quality characteristics. The aim of this paper is to develop a fuzzy logic model that predicts the influence of variable process parameters on dross height in plasma jet cutting of aluminium alloy 5083. Experiments were performed according to Taguchi L27 orthogonal array by varying cutting speed, arc current and cutting height as input process parameters. Fuzzy logic model was defined using Mamdani inference system. This model was used to investigate effects of variable process parameters on dross height response. In order to analyse interaction effects of plasma jet cutting process parameters on dross formation 3D surface and contour plots were generated. The analysis revealed that the cutting speed has the most significant effect followed by arc current and cutting height. Obtained results of this research indicate that artificial intelligence technique, fuzzy logic, can be effectively used for modelling and prediction of dross formation in plasma jet cutting process of aluminium alloy.
Laser beam machining (LBM) is one of the lately most used nonconventional machining processes. It... more Laser beam machining (LBM) is one of the lately most used nonconventional machining processes. It is based on melting and evaporation of processed material. It can be applied to almost a whole range of materials. Lately, it has been increasingly used for mark-engraving materials, as well as for milling less demanding 3D shapes. This paper presents the results of research on the possibility of laser milling of plexiglass. The influence of the cutting speed, laser power and the radial step on the machined surface roughness and depth of the cut was analyzed. It was concluded that increase in radial step and cutting speed causes lover values of the depth of cut. Laser milling with higher laser pover leads to higher values of depth of cut. Influence of mentioned laser machining parameters on surface roughness of machined surface is obvious, but it is necessary to realize more detail investigation on this subject.
Na uzorcima korozijski postojanih celika, provedena su laboratorijska ispitivanja te ispitivanja ... more Na uzorcima korozijski postojanih celika, provedena su laboratorijska ispitivanja te ispitivanja uzoraka u stvarnim uvjetima trosenja. Elektrokemijska ispitivanja provedena su u cilju provjere korozijske otpornosti modificiranih povrsina celika. Na uzorcima korozijski postojanih celika X20Cr13 i X17CrNi16-2, provedena je metalografska analiza i ispitivanje tvrdoce. Mogucnost primjene modificiranih povrsina na odabranim celicima, provjerena je ispitivanjem uzoraka u stvarnim uvjetima trosenja. Dobiveni rezultati pokazuju da su indukcijski zakaljeni i naknadno nitrirani martenzitni celici prosjecno postigli otpornost trosenju do tri reda velicine vecu u odnosu na dostavno stanje.
The purpose of this paper is to present new approach in drilling path optimization based on genet... more The purpose of this paper is to present new approach in drilling path optimization based on genetic algorithm and to present a practically applicable software solution in everu day practice. It deals with multi-hole drilling problem with precedence constraints which is common case in metalworking industry. The starting point is the assumption that the geometry of the workpiece is already recognized, then the mathematical model is presented and genetic algorithm is used to generate and to optimize tool path. Proposed concept greatly reduced the costs of part production through improved machining efficiency and it is very suitable for small and medium enterprises (SMEs) which have limited resources. Proposed concept is realised through software solution implemented in object-oriented programming language Delphi, and can be used for automatic generation of NC code.
The paper presents a numerical analysis, using the finite element method, for the case of static ... more The paper presents a numerical analysis, using the finite element method, for the case of static and dynamic loading of the upper carriage of the remote-controlled combat station, due to the recoil force generated by the operation of the integrated automatic grenade launcher 30mm M93. The paper describes the problem of integrating the BGA 30mm M93 automatic grenade launcher onto the combat platform, and based on the dimensions of the automatic launcher, modeling of the automatic launcher stand with cradle was carried out. As a result of the weapon dynamics equations and internal ballistics calculations, the pressure force of the gunpowder gases and the recoil force of the automatic grenade launcher were calculated. The paper also presents the results of the dynamic analysis of the finite element model of the upper gun carriage loaded with the obtained impulse recoil force for different elevation angles of the weapon.
Mechanical tests were performed on samples prepared from the body and the neck of bottles made of... more Mechanical tests were performed on samples prepared from the body and the neck of bottles made of seamless tube, steel 34CrMo4. Plastic material flow curves were taken from tensile tests on samples which were made from tubes and finished bottles. Deformation hardening intensity is calculated, and propensity towards brittle fracture is estimated on the basis of the ratio of total elongation and elongation at maximum load. Compared to the samples of quenched and tempered bottle body, quenched and tempered bottle neck samples indicate that characteristics of strength are almost unchanged with an increase in the minimum strain at the destruction from 12,8% to 15,1%. It was concluded that the results of the plastic material flow can serve as a preliminary indication of anomalies that could contribute to unsatisfactory results of the burst test.
In this paper an approach for multi-criteria analysis of laser cut surface characteristics using ... more In this paper an approach for multi-criteria analysis of laser cut surface characteristics using multi-criteria decision making (MCDM) approach was presented. Laser cutting experiment was conducted based on Taguchi's L27 experimental design by varying laser power, cutting speed, assist gas pressure and focus position at three levels. Multi-criteria analysis was performed by using the weighted aggregated sum product assessment (WASPAS) method while considering burr height, drag line separation, depth of separation line, surface roughness and perpendicularity of the cut as assessment criteria. Based on conducted experimental investigation the MCDM model with 27 alternatives (laser cuts) and five criteria was developed. The relative importance of criteria was determined by using pairwise comparison matrix and geometric mean method of the analytic hierarchy process (AHP) method.
DOAJ (DOAJ: Directory of Open Access Journals), Dec 1, 2016
Today highly competitive market and demands for obtain high surface finish and machining of compl... more Today highly competitive market and demands for obtain high surface finish and machining of complex shape geometries replace conventional machining processes with non-conventional. Plasma jet cutting is one of these non-conventional processes that primary uses a thermal energy of highly ionized gas to cut specified material and blow molten metal away. Main advantages of plasma jet cutting process are high speed of cutting, cutting different types of materials, the quality of cut and moderate to low investment costs. This paper presents experimental results concerning the surface roughness variation at plasma jet cutting of structural steel S235JRG2 plate thickness of 15 mm. Using the experimental data artificial neural network (ANN) model was developed in order to predict the surface roughness in terms of two input parameters, cutting current and cutting speed. After the prediction accuracy of the developed model was validated, the model was used for analyzing influence of input parameters on process response values.
This paper presents a systematic methodology for empirical modeling and optimization of surface r... more This paper presents a systematic methodology for empirical modeling and optimization of surface roughness in CO 2 laser nitrogen cutting of stainless steel. The surface roughness prediction model was developed in terms of laser power, cutting speed, assist gas pressure and focus position by using the artificial neural network (ANN). To cover a wider range of laser cutting parameters and obtain an experimental database for the ANN model development, Taguchi's L 27 orthogonal array was implemented in the experimental plan. The developed ANN model was expressed as an explicit nonlinear function, while the influence of laser cutting parameters and their interactions on surface roughness were analyzed by generating 2D and 3D plots. The final goal of the experimental study focuses on the determination of the optimal laser cutting parameters for the minimization of surface roughness. Since the solution space of the developed ANN model is complex, and the possibility of many local solutions is great, simulated annealing (SA) was selected as a method for the optimization of surface roughness.
Machining of aluminum and its alloys requires the use of cutting tools with special geometry and ... more Machining of aluminum and its alloys requires the use of cutting tools with special geometry and material. Since there exists a number of cutting tools for aluminum machining, each with unique characteristics, selection of the most appropriate cutting tool for a given application is very complex task which can be viewed as a multi-criteria decision making (MCDM) problem. This paper is focused on multi-criteria analysis of VCGT cutting inserts for aluminum alloys turning by applying recently developed MCDM method, i.e. weighted aggregated sum product assessment (WASPAS) method. The MCDM model was defined using the available catalogue data from cutting tool manufacturers.
Heat affected zone (HAZ) of the laser cutting process may be developed based on combination of di... more Heat affected zone (HAZ) of the laser cutting process may be developed based on combination of different factors. In this investigation the HAZ forecasting, based on the different laser cutting parameters, was analyzed. The main goal was to predict the HAZ according to three inputs. The purpose of this research was to develop and apply the Extreme Learning Machine (ELM) to predict the HAZ. The ELM results were compared with genetic programming (GP) and artificial neural network (ANN). The reliability of the computational models were accessed based on simulation results and by using several statistical indicators. Based upon simulation results, it was demonstrated that ELM can be utilized effectively in applications of HAZ forecasting.
Solar energy is very important alternative energy due to the vase deposit. The main goal of the s... more Solar energy is very important alternative energy due to the vase deposit. The main goal of the study was to analyze the solar radiation based on the four parameters: mean sea level (MSL), dry-bulb temperature (DBT), wet-bulb temperature (WBT) and relative humidity (RH). Adaptive neuro-fuzzy inference system (ANFIS) was used in order to estimate the parameters influence on the solar radiation prediction. Variable selection process was used to select the most dominant factors which affect the solar radiation prediction. The results shown that the DBT and RH are the most dominant factors for the solar radiation prediction.
Bimetallic materials are construction materials that are increasingly used in many industries: in... more Bimetallic materials are construction materials that are increasingly used in many industries: in the graphic industry, tobacco processing industry for various cutting knives, in the chemical industry for various plants and vessels, food industry, military industry, etc. In the production of ships, their use becomes dominant, primarily as a combination of cheap construction materials highly resistant to corrosion, at a price closer to construction materials. The appearance of plating with the help of explosion energy has significantly increased the range and quality of available multilayer metals. Although stainless steels and aluminum are the most commonly used material for bimetallic and clad materials, materials such as titanium, zirconium or tantalum are increasingly used. The paper analyzes the process of explosion welding and the results of exploration of the explosion of a welded joint of copper and brass. The microhardness of the material in the welded joint, tribological characteristics and scratch test joint were analyzed.
The last two decades have seen a dramatic shift in use of technology to drive improvements in man... more The last two decades have seen a dramatic shift in use of technology to drive improvements in manufacturing operations. Just twenty years ago, many small and mid-size manufacturers relied on paper-based systems to run their businesses. The application of advanced technologies in manufacturing such as nanotechnology, cloud computing, the Internet of Things (IoT) are changing the face of manufacturing in ways unimaginable a few decades ago. In addition to cutting the costs, these technologies create speed, precision, efficiency and flexibility for manufacturing companies. Technologies that have the greatest impact include cloud, mobile, big data and analytics, internet of things (IoT), robotics, cognitive computing/artificial intelligence (AI), 3D printing, augmented reality/virtual reality (AR/VR), and even blockchain. In the paper is presented top 10 strategic technology trends for 2012 to 2019 that the every year compani Gartner, Inc. from the IT Symposium/Xpo stage, we unveil our for the following year that CIOs and other senior executives should be paying attention to.
In the paper examined was the influence of the cutting regime parameters on surface roughness par... more In the paper examined was the influence of the cutting regime parameters on surface roughness parameters during turning of hard steel with cubic boron nitrite cutting insert. In this study for modeling of surface finish parameters was used central compositional design of experiment and artificial neural network. The values of surface roughness parameters Ra and Rt were predicted by this two-modeling methodology and determined models were then compared. The results showed that the proposed systems can significantly increase the accuracy of the product profile when compared to the conventional approaches. The results indicate that the design of experiments with central composition plan modeling technique and artificial neural network can be effectively used for the prediction of the surface roughness for hard steel and determined significand cutting regime parameters.
Dross height is an important cut quality characteristic in plasma jet cutting process. It can be ... more Dross height is an important cut quality characteristic in plasma jet cutting process. It can be defined as molten metal blown from the cutting zone and localized on the bottom of the metal sheet. In each plasma jet cutting process, it is important to obtain dross free cuts. Aluminium is as material very present in shipbuilding and metal industry and because of that very usually cut by plasma jet. Because of high heat and electrical conductivity of aluminium, plasma jet cutting is followed by insecurity about process parameters settings that lead to optimal cut quality characteristics. The aim of this paper is to develop a fuzzy logic model that predicts the influence of variable process parameters on dross height in plasma jet cutting of aluminium alloy 5083. Experiments were performed according to Taguchi L27 orthogonal array by varying cutting speed, arc current and cutting height as input process parameters. Fuzzy logic model was defined using Mamdani inference system. This model was used to investigate effects of variable process parameters on dross height response. In order to analyse interaction effects of plasma jet cutting process parameters on dross formation 3D surface and contour plots were generated. The analysis revealed that the cutting speed has the most significant effect followed by arc current and cutting height. Obtained results of this research indicate that artificial intelligence technique, fuzzy logic, can be effectively used for modelling and prediction of dross formation in plasma jet cutting process of aluminium alloy.
Laser beam machining (LBM) is one of the lately most used nonconventional machining processes. It... more Laser beam machining (LBM) is one of the lately most used nonconventional machining processes. It is based on melting and evaporation of processed material. It can be applied to almost a whole range of materials. Lately, it has been increasingly used for mark-engraving materials, as well as for milling less demanding 3D shapes. This paper presents the results of research on the possibility of laser milling of plexiglass. The influence of the cutting speed, laser power and the radial step on the machined surface roughness and depth of the cut was analyzed. It was concluded that increase in radial step and cutting speed causes lover values of the depth of cut. Laser milling with higher laser pover leads to higher values of depth of cut. Influence of mentioned laser machining parameters on surface roughness of machined surface is obvious, but it is necessary to realize more detail investigation on this subject.
Na uzorcima korozijski postojanih celika, provedena su laboratorijska ispitivanja te ispitivanja ... more Na uzorcima korozijski postojanih celika, provedena su laboratorijska ispitivanja te ispitivanja uzoraka u stvarnim uvjetima trosenja. Elektrokemijska ispitivanja provedena su u cilju provjere korozijske otpornosti modificiranih povrsina celika. Na uzorcima korozijski postojanih celika X20Cr13 i X17CrNi16-2, provedena je metalografska analiza i ispitivanje tvrdoce. Mogucnost primjene modificiranih povrsina na odabranim celicima, provjerena je ispitivanjem uzoraka u stvarnim uvjetima trosenja. Dobiveni rezultati pokazuju da su indukcijski zakaljeni i naknadno nitrirani martenzitni celici prosjecno postigli otpornost trosenju do tri reda velicine vecu u odnosu na dostavno stanje.
The purpose of this paper is to present new approach in drilling path optimization based on genet... more The purpose of this paper is to present new approach in drilling path optimization based on genetic algorithm and to present a practically applicable software solution in everu day practice. It deals with multi-hole drilling problem with precedence constraints which is common case in metalworking industry. The starting point is the assumption that the geometry of the workpiece is already recognized, then the mathematical model is presented and genetic algorithm is used to generate and to optimize tool path. Proposed concept greatly reduced the costs of part production through improved machining efficiency and it is very suitable for small and medium enterprises (SMEs) which have limited resources. Proposed concept is realised through software solution implemented in object-oriented programming language Delphi, and can be used for automatic generation of NC code.
The paper presents a numerical analysis, using the finite element method, for the case of static ... more The paper presents a numerical analysis, using the finite element method, for the case of static and dynamic loading of the upper carriage of the remote-controlled combat station, due to the recoil force generated by the operation of the integrated automatic grenade launcher 30mm M93. The paper describes the problem of integrating the BGA 30mm M93 automatic grenade launcher onto the combat platform, and based on the dimensions of the automatic launcher, modeling of the automatic launcher stand with cradle was carried out. As a result of the weapon dynamics equations and internal ballistics calculations, the pressure force of the gunpowder gases and the recoil force of the automatic grenade launcher were calculated. The paper also presents the results of the dynamic analysis of the finite element model of the upper gun carriage loaded with the obtained impulse recoil force for different elevation angles of the weapon.
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