Antonio Ludovico - Academia.edu (original) (raw)

Papers by Antonio Ludovico

In this experimental work the weldability of an Al alloy AA 2024-T3 by using two different laser ... more In this experimental work the weldability of an Al alloy AA 2024-T3 by using two different laser sources, (CO2 and Nd:YAG), has been tested for experiments. A ROFIN SINAR, 1500 W continuous wave (c.w.) max power level, emitting at 10.6 mum, and a HAAS TRUMPH source, 3000 W max power level, pulsed beam, that produces na 1.06 mum wavelength have been used. The thicknesses employed are 0.8-1.6 and 2.0 mm for the Nd:YAG, 1 and 1.6 mm for the CO2. In order to define a possible laser welding process optimisation versus the best quality and relative mechanical properties of the butt joints, different laser working parameters have been studied and experimented. Moreover two diverse welding techniques, that is by using a filler wire or without one have been applied and the relative results have been compared. The best selected butt joints have been cahracterized by some visual examinations, micro and macrographs of transverse sections, micro-hardness data and plots as well as some tensile te...

Materials, 2016

A simulation model was developed for the monitoring, controlling and optimization of the Friction... more A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW) process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable) and the mechanical properties (output responses) of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls). The simulation model was based on the adoption of the Artificial Neural Networks (ANNs) characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration.

Even if many steels and alloys have been welded on the last years, nowadays there are some other ... more Even if many steels and alloys have been welded on the last years, nowadays there are some other stainless steel alloys that need a further comprehension when they have to be welded. Typically these alloys are martensitic and precipitation hardening ones that still present some problems to be weld, i.e. hot cracks, fragile beads, an excessive grain size and other

This paper reports the results obtained by employing materials such as austenitic stainless steel... more This paper reports the results obtained by employing materials such as austenitic stainless steel (AISI 304) sheets, with different face thicknesses and core geometry's, usually some trapezoidal ones. A ROFIN SINAR C.W.CO2 laser has been used as a fast axial flow source and a 1500 W max power level to weld the many bases of the corrugated cores to the

Advanced Materials Research, 2012

ABSTRACT The new generation of high power fiber lasers presents several benefits for industrial a... more ABSTRACT The new generation of high power fiber lasers presents several benefits for industrial application. Nevertheless, due to the small spot size of the laser, the fiber laser has difficulties in some welding applications. These shortcomings can be overcome by laser-arc hybrid welding technique such as laser-gas metal arc welding or laser-gas tungsten arc welding. In this work, a high power fiber laser was coupled to an arc welder and the AA5754-H111 magnesium aluminum alloy was welded. The trials were carried out using laser leading configuration. A new generation of high power fiber laser was used. The experimental trials included process parameters such as laser power, welding speed and arc current. Microstructure, microhardness and weld appearance were analyzed. The experimental results showed that laser leading configuration produces full penetration for some welding parameters. The obtained results worth a larger investigation based on the experimental design technique.

9th International Symposium on Gas Flow and Chemical Lasers, 1993

XV International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers, 2005

High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications III, 2014

ABSTRACT Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. T... more ABSTRACT Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. The laser Assisted Friction Stir Welding (LAFSW) combines a Friction Stir Welding machine and a laser system. Laser power is used to preheat and to plasticize the volume of the workpiece ahead of the rotating tool; the workpiece is then joined in the same way as in the conventional FSW process. In this work an Ytterbium fiber laser with maximum power of 4 kW and a commercial FSW machine were coupled. Both FSW and LAFSW tests were conducted on 3 mm thick 5754H111 aluminum alloy plates in lap joint configuration with a constant tool rotation rate and with different feed rates. The two processes were compared and evaluated in terms of differences in the microstructure and in the micro-hardness profile.

Lasers in Material Processing, 1997

Lasers in Material Processing, 1997

XIII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference, 2001

Volume 4184 N eural networks optimisation of laser welding process 8 Dip. Ing. Meccanica-Uni v. d... more Volume 4184 N eural networks optimisation of laser welding process 8 Dip. Ing. Meccanica-Uni v. di Salerno -Via Ponte Don Melillo -84084 Fisciano -Salerno (ltaly) bCentro Laser S.c.ar.l.-Str. Provinciale per Casamassima km 3 -70010 Valenzano Bari (Italy) cDip. di Progettazione e Produzione lnd. -Politecnico di Bari-V.le Japigia, 182 -70126 Bari (ltaly) dDip. Ing. Materiali e Prod.-Univ. di Napoli ''Federico II'' -P .le Tecchio, 80-80125 Napoli (Italy)

Lasers and Applications, 2005

ABSTRACT Worldwide manufacturers have already recognized the advantages of using laser welding fo... more ABSTRACT Worldwide manufacturers have already recognized the advantages of using laser welding for a number of applications. Although laser welding is usually performed autogenously, the use of wire filler allows a broader range of welding applications. In this paper a finite element model for key-hole laser welding sources based on experimental observations is presented. The shape for the heat source can be easily changed so to simulate both autogeneous and wire filler laser welding. In the thermal and mechanical calculations the material properties were considered with full temperature dependence. Austenitic stainless and aluminum alloy welds were chosen to validate the model. Simulations of out-of-plane welds were computed using a local coordinates system. A personal computer was used for the calculations. For different plate thicknesses and weld geometries, the calculated fused zones were found in very good agreement with the experimental ones, which proved that the thermal history was computed correctly. When materials with thermal induced microstructure changes are welded, the microstructure in every point of the heat affected zones can be determined as a function of the local temperature cycle.

Second GR-I International Conference on New Laser Technologies and Applications, 1998

XV International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers, 2005

In this experimental work the weldability of an Al alloy AA 2024-T3 by using two different laser ... more In this experimental work the weldability of an Al alloy AA 2024-T3 by using two different laser sources, (CO2 and Nd:YAG), has been tested for experiments. A ROFIN SINAR, 1500 W continuous wave (c.w.) max power level, emitting at 10.6 mum, and a HAAS TRUMPH source, 3000 W max power level, pulsed beam, that produces na 1.06 mum wavelength have been used. The thicknesses employed are 0.8-1.6 and 2.0 mm for the Nd:YAG, 1 and 1.6 mm for the CO2. In order to define a possible laser welding process optimisation versus the best quality and relative mechanical properties of the butt joints, different laser working parameters have been studied and experimented. Moreover two diverse welding techniques, that is by using a filler wire or without one have been applied and the relative results have been compared. The best selected butt joints have been cahracterized by some visual examinations, micro and macrographs of transverse sections, micro-hardness data and plots as well as some tensile tests. Finally, according to the results as above, physical-technological evaluations and comparisons have been reported.

New Trends in Technologies: Devices, Computer, Communication and Industrial Systems, 2010

Journal of the American Ceramic Society, 1999

Page 1. Effect of Processing Parameters on the Morphology of Hydrothermally Derived PbTiO3 Powder... more Page 1. Effect of Processing Parameters on the Morphology of Hydrothermally Derived PbTiO3 Powders Chad R. Peterson* and Elliott B. Slamovich* School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 ...

Proceedings of SPIE, 1810

This work concerns a study on the integration of a laser system with a speech synthesis facility.... more This work concerns a study on the integration of a laser system with a speech synthesis facility. The speech synthesis system uses a random access memory (RAM) and electrical contacts (NO and/or NC), controlled by an electronic circuit provided with a microprocessor, in ...

Proceedings of the …, 2007

Aluminium foams, produced by the powder metallurgy route, have a high potential for use in weight... more Aluminium foams, produced by the powder metallurgy route, have a high potential for use in weight-sensitive construction parts. The stiffness to weight ratio is the main criterion for material selection in light-weight design. The aim of this study is to evaluate the properties and to optimize the control factors of a powder technique, developed at the Fraunhofer Institute, starting from aluminium powders with titanium hydride as the foaming agent. During the experimental work, many samples were made following the principles of the design of experiment. Then a study of the morphology and distribution of cells and of the walls of the cells was carried out and relative density was measured. Mechanical properties of foam samples were studied by quasi-static compression tests. The final evaluation of the most important features has been made using ANOVA statistical analysis.

Applied Mechanics and Materials, 2012

ABSTRACT Laser ablation is a new, very flexible process for micro-fabrication of micro-moulds and... more ABSTRACT Laser ablation is a new, very flexible process for micro-fabrication of micro-moulds and other micro-system devices. This process is suitable for machining difficult-to-machine materials, like ceramics, dielectrics, carbide and hardened steel with excellent productivity and surface. The paper presents the investigation on the material removal rate of aluminium 5754 using a nanosecond Nd:YAG laser with a wavelength of 1064 nm.

In this experimental work the weldability of an Al alloy AA 2024-T3 by using two different laser ... more In this experimental work the weldability of an Al alloy AA 2024-T3 by using two different laser sources, (CO2 and Nd:YAG), has been tested for experiments. A ROFIN SINAR, 1500 W continuous wave (c.w.) max power level, emitting at 10.6 mum, and a HAAS TRUMPH source, 3000 W max power level, pulsed beam, that produces na 1.06 mum wavelength have been used. The thicknesses employed are 0.8-1.6 and 2.0 mm for the Nd:YAG, 1 and 1.6 mm for the CO2. In order to define a possible laser welding process optimisation versus the best quality and relative mechanical properties of the butt joints, different laser working parameters have been studied and experimented. Moreover two diverse welding techniques, that is by using a filler wire or without one have been applied and the relative results have been compared. The best selected butt joints have been cahracterized by some visual examinations, micro and macrographs of transverse sections, micro-hardness data and plots as well as some tensile te...

Materials, 2016

A simulation model was developed for the monitoring, controlling and optimization of the Friction... more A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW) process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable) and the mechanical properties (output responses) of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls). The simulation model was based on the adoption of the Artificial Neural Networks (ANNs) characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration.

Even if many steels and alloys have been welded on the last years, nowadays there are some other ... more Even if many steels and alloys have been welded on the last years, nowadays there are some other stainless steel alloys that need a further comprehension when they have to be welded. Typically these alloys are martensitic and precipitation hardening ones that still present some problems to be weld, i.e. hot cracks, fragile beads, an excessive grain size and other

This paper reports the results obtained by employing materials such as austenitic stainless steel... more This paper reports the results obtained by employing materials such as austenitic stainless steel (AISI 304) sheets, with different face thicknesses and core geometry's, usually some trapezoidal ones. A ROFIN SINAR C.W.CO2 laser has been used as a fast axial flow source and a 1500 W max power level to weld the many bases of the corrugated cores to the

Advanced Materials Research, 2012

ABSTRACT The new generation of high power fiber lasers presents several benefits for industrial a... more ABSTRACT The new generation of high power fiber lasers presents several benefits for industrial application. Nevertheless, due to the small spot size of the laser, the fiber laser has difficulties in some welding applications. These shortcomings can be overcome by laser-arc hybrid welding technique such as laser-gas metal arc welding or laser-gas tungsten arc welding. In this work, a high power fiber laser was coupled to an arc welder and the AA5754-H111 magnesium aluminum alloy was welded. The trials were carried out using laser leading configuration. A new generation of high power fiber laser was used. The experimental trials included process parameters such as laser power, welding speed and arc current. Microstructure, microhardness and weld appearance were analyzed. The experimental results showed that laser leading configuration produces full penetration for some welding parameters. The obtained results worth a larger investigation based on the experimental design technique.

9th International Symposium on Gas Flow and Chemical Lasers, 1993

XV International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers, 2005

High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications III, 2014

ABSTRACT Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. T... more ABSTRACT Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. The laser Assisted Friction Stir Welding (LAFSW) combines a Friction Stir Welding machine and a laser system. Laser power is used to preheat and to plasticize the volume of the workpiece ahead of the rotating tool; the workpiece is then joined in the same way as in the conventional FSW process. In this work an Ytterbium fiber laser with maximum power of 4 kW and a commercial FSW machine were coupled. Both FSW and LAFSW tests were conducted on 3 mm thick 5754H111 aluminum alloy plates in lap joint configuration with a constant tool rotation rate and with different feed rates. The two processes were compared and evaluated in terms of differences in the microstructure and in the micro-hardness profile.

Lasers in Material Processing, 1997

Lasers in Material Processing, 1997

XIII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference, 2001

Volume 4184 N eural networks optimisation of laser welding process 8 Dip. Ing. Meccanica-Uni v. d... more Volume 4184 N eural networks optimisation of laser welding process 8 Dip. Ing. Meccanica-Uni v. di Salerno -Via Ponte Don Melillo -84084 Fisciano -Salerno (ltaly) bCentro Laser S.c.ar.l.-Str. Provinciale per Casamassima km 3 -70010 Valenzano Bari (Italy) cDip. di Progettazione e Produzione lnd. -Politecnico di Bari-V.le Japigia, 182 -70126 Bari (ltaly) dDip. Ing. Materiali e Prod.-Univ. di Napoli ''Federico II'' -P .le Tecchio, 80-80125 Napoli (Italy)

Lasers and Applications, 2005

ABSTRACT Worldwide manufacturers have already recognized the advantages of using laser welding fo... more ABSTRACT Worldwide manufacturers have already recognized the advantages of using laser welding for a number of applications. Although laser welding is usually performed autogenously, the use of wire filler allows a broader range of welding applications. In this paper a finite element model for key-hole laser welding sources based on experimental observations is presented. The shape for the heat source can be easily changed so to simulate both autogeneous and wire filler laser welding. In the thermal and mechanical calculations the material properties were considered with full temperature dependence. Austenitic stainless and aluminum alloy welds were chosen to validate the model. Simulations of out-of-plane welds were computed using a local coordinates system. A personal computer was used for the calculations. For different plate thicknesses and weld geometries, the calculated fused zones were found in very good agreement with the experimental ones, which proved that the thermal history was computed correctly. When materials with thermal induced microstructure changes are welded, the microstructure in every point of the heat affected zones can be determined as a function of the local temperature cycle.

Second GR-I International Conference on New Laser Technologies and Applications, 1998

XV International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers, 2005

In this experimental work the weldability of an Al alloy AA 2024-T3 by using two different laser ... more In this experimental work the weldability of an Al alloy AA 2024-T3 by using two different laser sources, (CO2 and Nd:YAG), has been tested for experiments. A ROFIN SINAR, 1500 W continuous wave (c.w.) max power level, emitting at 10.6 mum, and a HAAS TRUMPH source, 3000 W max power level, pulsed beam, that produces na 1.06 mum wavelength have been used. The thicknesses employed are 0.8-1.6 and 2.0 mm for the Nd:YAG, 1 and 1.6 mm for the CO2. In order to define a possible laser welding process optimisation versus the best quality and relative mechanical properties of the butt joints, different laser working parameters have been studied and experimented. Moreover two diverse welding techniques, that is by using a filler wire or without one have been applied and the relative results have been compared. The best selected butt joints have been cahracterized by some visual examinations, micro and macrographs of transverse sections, micro-hardness data and plots as well as some tensile tests. Finally, according to the results as above, physical-technological evaluations and comparisons have been reported.

New Trends in Technologies: Devices, Computer, Communication and Industrial Systems, 2010

Journal of the American Ceramic Society, 1999

Page 1. Effect of Processing Parameters on the Morphology of Hydrothermally Derived PbTiO3 Powder... more Page 1. Effect of Processing Parameters on the Morphology of Hydrothermally Derived PbTiO3 Powders Chad R. Peterson* and Elliott B. Slamovich* School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 ...

Proceedings of SPIE, 1810

This work concerns a study on the integration of a laser system with a speech synthesis facility.... more This work concerns a study on the integration of a laser system with a speech synthesis facility. The speech synthesis system uses a random access memory (RAM) and electrical contacts (NO and/or NC), controlled by an electronic circuit provided with a microprocessor, in ...

Proceedings of the …, 2007

Aluminium foams, produced by the powder metallurgy route, have a high potential for use in weight... more Aluminium foams, produced by the powder metallurgy route, have a high potential for use in weight-sensitive construction parts. The stiffness to weight ratio is the main criterion for material selection in light-weight design. The aim of this study is to evaluate the properties and to optimize the control factors of a powder technique, developed at the Fraunhofer Institute, starting from aluminium powders with titanium hydride as the foaming agent. During the experimental work, many samples were made following the principles of the design of experiment. Then a study of the morphology and distribution of cells and of the walls of the cells was carried out and relative density was measured. Mechanical properties of foam samples were studied by quasi-static compression tests. The final evaluation of the most important features has been made using ANOVA statistical analysis.

Applied Mechanics and Materials, 2012

ABSTRACT Laser ablation is a new, very flexible process for micro-fabrication of micro-moulds and... more ABSTRACT Laser ablation is a new, very flexible process for micro-fabrication of micro-moulds and other micro-system devices. This process is suitable for machining difficult-to-machine materials, like ceramics, dielectrics, carbide and hardened steel with excellent productivity and surface. The paper presents the investigation on the material removal rate of aluminium 5754 using a nanosecond Nd:YAG laser with a wavelength of 1064 nm.