CuCrZr alloy is used to produce actively cooled components for high heat flux elements of beamlin... more CuCrZr alloy is used to produce actively cooled components for high heat flux elements of beamlines and for heat sink of plasma facing components in nuclear fusion devices such as ITER and DEMO. It has an excellent thermal conductivity and specific mechanical strength, together with a high electrical conductivity that is giving high push to its use. Recently, CuCrZr alloy was also considered as an attractive material for Additive Manufacturing, leading to extend its application in the field of strain rate studies. As a matter of fact, its strain rate dependency is playing an important role for vertical target plasma-facing units components uses as heat sink in the ITER divertor or as structural material for actively cooled plasma facing components. This paper describes the results obtained by quasi-static and dynamic compression tests carried out on CuCrZr specimens produced by laser Powder Bed Fusion (PBF), with Selective Laser Melting (SLM) technology. Quasi-static tests have been conducted by means a servo-hydraulic tensile machine, while a direct tension-compression split Hopkinson bar has been used to perform the tests at high strain rate. Since dedicated heat treatments are required to obtain optimal combination of strength, ductility, and conductivity, some of the specimens have been heated up to 560 – 580 °C for 4 – 5 h and then cooled in air. Eventually, the calibration of the most appropriate constitutive models for 3D-printed CuCrZr alloy deformed at high strain rate has been carried out by means an inverse analytical procedure.
IOP Conference Series: Materials Science and Engineering
The main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee ... more The main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee high mechanical properties. Therefore, it is necessary easily figure out the most suitable structure for the required design requirements. The well-known strategy to design sandwich panels is evaluating collapse maps as they determine the panel performances based on their geometrical features. The aim of this study is to update the traditional collapse maps by showing how the core shape can improve the sandwich beam performance. The collapse maps proposed are based on advanced analytical models than the traditional Gibson theories. The analytical modelling of the indentation phenomenon is based on Vlasov’s model. The analytical modelling of the bending phenomenon is based on the First Shear Order Theory. The overall panel stress and strain maps are computed superposing both effects. A composite sandwich panels with Gyroid core based are analyzed to verify the proposed model consistency. ...
The main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee ... more The main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee high mechanical properties. Therefore, it is necessary easily figure out the most suitable structure for the required design requirements. The well-known strategy to design sandwich panels is evaluating collapse maps as they determine the panel performances based on their geometrical features. The aim of this study is to update the traditional collapse maps by showing how the core shape can improve the sandwich beam performance. The collapse maps proposed are based on advanced analytical models than the traditional Gibson theories. The analytical modelling of the indentation phenomenon is based on Vlasov’s model. The analytical modelling of the bending phenomenon is based on the First Shear Order Theory. The overall panel stress and strain maps are computed superposing both effects. A composite sandwich panels with Gyroid core based are analyzed to verify the proposed model consistency. A core failure criterion is chosen by experimental testing evidence on the representative core structure. Once the computed stress state overtakes failure criterion ones, the critical load is defined. In the end, the model is exploited to compare the performances of four sandwich panels with cores based on different lattice structures.
The TPMS (triply periodic minimal surface) are receiving great attention for production of open c... more The TPMS (triply periodic minimal surface) are receiving great attention for production of open cell scaffold structures, for example in biomedical applications. In this paper stretch-dominated lattice structures have been considered. The Gyroid cell made of epoxy resin by DLP technology was analyzed. The compression test results in quasi-static (10-3 s-1) and dynamic (4x102 s-1) conditions have been used to compute the macroscopic cellular material properties by the homogenization methods. Finally, in order to evaluate the behaviour of the unit cell under multi-axial stress state, combined shear-compression tests have been carried out as well.
Nowadays cellular materials are receiving great attention for their excellent mechanical properti... more Nowadays cellular materials are receiving great attention for their excellent mechanical properties, being applied in energy absorbers or in structural components having optimized mass distribution. In this paper stretch-dominated lattice structures have been considered. A 3D periodic lattice structure of different cell size, TPMS (triply periodic minimal surface), made of epoxy resin by DLP technology was studied. Compression tests at different strain rate (10-3 to 103 1/s) have been performed and a constitutive model to assess the experimental findings has been calibrated.
Thermomechanics & Infrared Imaging, Inverse Problem Methodologies, Mechanics of Additive & Advanced Manufactured Materials, and Advancements in Optical Methods & Digital Image Correlation, Volume 4
Journal of Engineering Materials and Technology-transactions of The Asme, 2021
Laser metal deposition (LMD) is an additive manufacturing process with an extreme potential in la... more Laser metal deposition (LMD) is an additive manufacturing process with an extreme potential in large-scale metal production. Among the printable metals, the Inconel 625 has found a wide variety of cutting-edge applications in the aerospace, defense, and space sectors. Thus, knowledge of mechanical properties under quasi-static and dynamic conditions is fundamental. In this work, the quasi-static and dynamic compression behavior of Inconel 625 obtained by LMD is presented. The curves of printed Inconel 625 showed a change in slope in the work hardening phase, which is due to the mechanics of the dislocation motion. Therefore, a modified two-stage (TS) Hollomon power-law is proposed to model this specific mechanical behavior, which identifies a threshold strain that delimit two different hardening behaviors. Furthermore, Johnson–Cook and Cowper–Symonds models were used to represent the effect of strain rate and temperature on the material properties. A variable strain rate sensitivity...
The paper provides an evaluation of the nonlinear dynamic response of a cantilever beam made of c... more The paper provides an evaluation of the nonlinear dynamic response of a cantilever beam made of composite material subjected to low-velocity impacts. The structure is assumed to respond in a quasi-static manner and modelled by a continuous beam in large displacement with a lumped mass attached. First, an analytical model was developed to study the free vibrations of a beam, taking into account the nonlinearities due to large displacements and inertia. Then, the analytical findings were compared with experimental test data. The vibration of a real composite beam has been acquired through high-speed imaging technique. The displacements of the beam were extracted by digital image analysis; then, the nonlinear parameters of the analytical model were determined by the Fitting Time History technique. The results obtained by the analytical model and the experimental test are compared with numerical analysis. The validated analytical model was adapted to study a low-velocity impact; the lum...
This paper investigates the nonlinear dynamic behavior of a cantilever beam made of composite mat... more This paper investigates the nonlinear dynamic behavior of a cantilever beam made of composite material without and with lumped mass fixed along its length. The analysis compares the results coming from analytical and numerical modeling with experimental observations. The first part focuses on the analytical model. The model takes into account the nonlinearity derived from large amplitude vibration and inertia. The second part deals with the experimental test, where the specimen and the data acquisition are defined. Then, the nonlinearity of the acquired data is determined by the fitting time history (FTH) technique. The third part deals with the finite element model. Finally, the results obtained by the analytical method, the experimental method, and the numerical method are compared between each other.
In the last few years, Fused Filament Fabrication is growing in the industrial field for the manu... more In the last few years, Fused Filament Fabrication is growing in the industrial field for the manufacture of final products by using new materials with high mechanical performances. Among those, one of the strongest is Carbon-PA. This is a composite material made by Nylon thermoplastic matrix filled with short carbon fibers reinforces. The aim of this work is to investigate its mechanical properties in static and dynamic conditions. Cylindrical specimens were produced by extruding the material in the three main printing directions. Then, uniaxial quasi-static and dynamic compression tests have been performed to evaluate its strain rate sensitivity. Dynamic tests have been carried out through a direct Split Hopkinson Bar setup with a pulse-shaping technique. The results show a compression behaviour dependent on the printing direction and strain rate. The behaviour of Carbon-PA was different between static and dynamic condition, passing from ductile to brittle. Moreover, a tomography a...
CuCrZr alloy is used to produce actively cooled components for high heat flux elements of beamlin... more CuCrZr alloy is used to produce actively cooled components for high heat flux elements of beamlines and for heat sink of plasma facing components in nuclear fusion devices such as ITER and DEMO. It has an excellent thermal conductivity and specific mechanical strength, together with a high electrical conductivity that is giving high push to its use. Recently, CuCrZr alloy was also considered as an attractive material for Additive Manufacturing, leading to extend its application in the field of strain rate studies. As a matter of fact, its strain rate dependency is playing an important role for vertical target plasma-facing units components uses as heat sink in the ITER divertor or as structural material for actively cooled plasma facing components. This paper describes the results obtained by quasi-static and dynamic compression tests carried out on CuCrZr specimens produced by laser Powder Bed Fusion (PBF), with Selective Laser Melting (SLM) technology. Quasi-static tests have been conducted by means a servo-hydraulic tensile machine, while a direct tension-compression split Hopkinson bar has been used to perform the tests at high strain rate. Since dedicated heat treatments are required to obtain optimal combination of strength, ductility, and conductivity, some of the specimens have been heated up to 560 – 580 °C for 4 – 5 h and then cooled in air. Eventually, the calibration of the most appropriate constitutive models for 3D-printed CuCrZr alloy deformed at high strain rate has been carried out by means an inverse analytical procedure.
IOP Conference Series: Materials Science and Engineering
The main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee ... more The main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee high mechanical properties. Therefore, it is necessary easily figure out the most suitable structure for the required design requirements. The well-known strategy to design sandwich panels is evaluating collapse maps as they determine the panel performances based on their geometrical features. The aim of this study is to update the traditional collapse maps by showing how the core shape can improve the sandwich beam performance. The collapse maps proposed are based on advanced analytical models than the traditional Gibson theories. The analytical modelling of the indentation phenomenon is based on Vlasov’s model. The analytical modelling of the bending phenomenon is based on the First Shear Order Theory. The overall panel stress and strain maps are computed superposing both effects. A composite sandwich panels with Gyroid core based are analyzed to verify the proposed model consistency. ...
The main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee ... more The main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee high mechanical properties. Therefore, it is necessary easily figure out the most suitable structure for the required design requirements. The well-known strategy to design sandwich panels is evaluating collapse maps as they determine the panel performances based on their geometrical features. The aim of this study is to update the traditional collapse maps by showing how the core shape can improve the sandwich beam performance. The collapse maps proposed are based on advanced analytical models than the traditional Gibson theories. The analytical modelling of the indentation phenomenon is based on Vlasov’s model. The analytical modelling of the bending phenomenon is based on the First Shear Order Theory. The overall panel stress and strain maps are computed superposing both effects. A composite sandwich panels with Gyroid core based are analyzed to verify the proposed model consistency. A core failure criterion is chosen by experimental testing evidence on the representative core structure. Once the computed stress state overtakes failure criterion ones, the critical load is defined. In the end, the model is exploited to compare the performances of four sandwich panels with cores based on different lattice structures.
The TPMS (triply periodic minimal surface) are receiving great attention for production of open c... more The TPMS (triply periodic minimal surface) are receiving great attention for production of open cell scaffold structures, for example in biomedical applications. In this paper stretch-dominated lattice structures have been considered. The Gyroid cell made of epoxy resin by DLP technology was analyzed. The compression test results in quasi-static (10-3 s-1) and dynamic (4x102 s-1) conditions have been used to compute the macroscopic cellular material properties by the homogenization methods. Finally, in order to evaluate the behaviour of the unit cell under multi-axial stress state, combined shear-compression tests have been carried out as well.
Nowadays cellular materials are receiving great attention for their excellent mechanical properti... more Nowadays cellular materials are receiving great attention for their excellent mechanical properties, being applied in energy absorbers or in structural components having optimized mass distribution. In this paper stretch-dominated lattice structures have been considered. A 3D periodic lattice structure of different cell size, TPMS (triply periodic minimal surface), made of epoxy resin by DLP technology was studied. Compression tests at different strain rate (10-3 to 103 1/s) have been performed and a constitutive model to assess the experimental findings has been calibrated.
Thermomechanics & Infrared Imaging, Inverse Problem Methodologies, Mechanics of Additive & Advanced Manufactured Materials, and Advancements in Optical Methods & Digital Image Correlation, Volume 4
Journal of Engineering Materials and Technology-transactions of The Asme, 2021
Laser metal deposition (LMD) is an additive manufacturing process with an extreme potential in la... more Laser metal deposition (LMD) is an additive manufacturing process with an extreme potential in large-scale metal production. Among the printable metals, the Inconel 625 has found a wide variety of cutting-edge applications in the aerospace, defense, and space sectors. Thus, knowledge of mechanical properties under quasi-static and dynamic conditions is fundamental. In this work, the quasi-static and dynamic compression behavior of Inconel 625 obtained by LMD is presented. The curves of printed Inconel 625 showed a change in slope in the work hardening phase, which is due to the mechanics of the dislocation motion. Therefore, a modified two-stage (TS) Hollomon power-law is proposed to model this specific mechanical behavior, which identifies a threshold strain that delimit two different hardening behaviors. Furthermore, Johnson–Cook and Cowper–Symonds models were used to represent the effect of strain rate and temperature on the material properties. A variable strain rate sensitivity...
The paper provides an evaluation of the nonlinear dynamic response of a cantilever beam made of c... more The paper provides an evaluation of the nonlinear dynamic response of a cantilever beam made of composite material subjected to low-velocity impacts. The structure is assumed to respond in a quasi-static manner and modelled by a continuous beam in large displacement with a lumped mass attached. First, an analytical model was developed to study the free vibrations of a beam, taking into account the nonlinearities due to large displacements and inertia. Then, the analytical findings were compared with experimental test data. The vibration of a real composite beam has been acquired through high-speed imaging technique. The displacements of the beam were extracted by digital image analysis; then, the nonlinear parameters of the analytical model were determined by the Fitting Time History technique. The results obtained by the analytical model and the experimental test are compared with numerical analysis. The validated analytical model was adapted to study a low-velocity impact; the lum...
This paper investigates the nonlinear dynamic behavior of a cantilever beam made of composite mat... more This paper investigates the nonlinear dynamic behavior of a cantilever beam made of composite material without and with lumped mass fixed along its length. The analysis compares the results coming from analytical and numerical modeling with experimental observations. The first part focuses on the analytical model. The model takes into account the nonlinearity derived from large amplitude vibration and inertia. The second part deals with the experimental test, where the specimen and the data acquisition are defined. Then, the nonlinearity of the acquired data is determined by the fitting time history (FTH) technique. The third part deals with the finite element model. Finally, the results obtained by the analytical method, the experimental method, and the numerical method are compared between each other.
In the last few years, Fused Filament Fabrication is growing in the industrial field for the manu... more In the last few years, Fused Filament Fabrication is growing in the industrial field for the manufacture of final products by using new materials with high mechanical performances. Among those, one of the strongest is Carbon-PA. This is a composite material made by Nylon thermoplastic matrix filled with short carbon fibers reinforces. The aim of this work is to investigate its mechanical properties in static and dynamic conditions. Cylindrical specimens were produced by extruding the material in the three main printing directions. Then, uniaxial quasi-static and dynamic compression tests have been performed to evaluate its strain rate sensitivity. Dynamic tests have been carried out through a direct Split Hopkinson Bar setup with a pulse-shaping technique. The results show a compression behaviour dependent on the printing direction and strain rate. The behaviour of Carbon-PA was different between static and dynamic condition, passing from ductile to brittle. Moreover, a tomography a...
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Papers by Mattia Utzeri