Carlo Rosso | Politecnico di Torino (original) (raw)
Papers by Carlo Rosso
Springer eBooks, 2013
Creep and stress relaxation are known to be interrelated in linearly viscoelastic materials by an... more Creep and stress relaxation are known to be interrelated in linearly viscoelastic materials by an exact analytical expression. In this article, analytical interrelations are derived for nonlinearly viscoelastic materials which obey a single integral nonlinear superposition constitutive equation. The kernel is not assumed to be separable as a product of strain and time dependent parts. Superposition is fully taken into account within the single integral formulation used. Specific formulations based on power law time dependence and truncated expansions are developed. These are appropriate for weak stress and strain dependence. The interrelated constitutive formulation is applied to ligaments, in which stiffness increases with strain, stress relaxation proceeds faster than creep, and rate of creep is a function of stress and rate of relaxation is a function of strain. An interrelation was also constructed for a commercial diecast aluminum alloy currently used in small engine applications.
IOP Conference Series: Materials Science and Engineering, 2021
In the latest years many researcher focused on the possibility to foresee the failure of a mechan... more In the latest years many researcher focused on the possibility to foresee the failure of a mechanical system in the early stages in order to allow quick response times. Monitoring and diagnostics are at the base of those methodologies of predictive maintenance, which represents the standard for companies. Data acquired by monitoring systems are sometimes not sufficient to perform an effective diagnosis and to detect failures. In the present work the possibility of a defining a relation between the response of a system and the dimension of a defect causing the vibration is explored. Through a non-Hertzian contact model a roller bearing is studied and a correlation is sought between the size of the defect and the frequency content of the contact pressure time history. Resorting to a non-Hertzian approach enables the determination with good accuracy of the overpressures due to edge effects caused by the sudden change in curvature in presence of a defect. The estimation of the pressure ...
IOP Conference Series: Materials Science and Engineering, 2021
The search for propulsion systems of vehicles with lower environmental impact is focusing on syst... more The search for propulsion systems of vehicles with lower environmental impact is focusing on systems with exclusive or supplementary use of electric motors. In fully electric or hybrid vehicles, the electric power delivery is used not only to provide torque to the vehicle and the consequent movement of the vehicle, but also to transform the vehicle’s kinetic energy back into electrical energy for storage in batteries when the vehicle is downhill or it must be slowed down. Under normal operating conditions, even in urban usage, it is common to have sudden inversions of the power flow. This means that in a really short time the motor switches from delivering torque to receiving it. Normally the electric motor is not directly connected on the wheels, but a geared transmission is present. The change of torque from positive (motor) to negative (generator) causes a sudden change of the working conditions. This induces vibrational and durability problems on the gears. In the present paper,...
In aerospace gearboxes, very thin gears are used in order to reduce the weight of the system. The... more In aerospace gearboxes, very thin gears are used in order to reduce the weight of the system. The low stiff of such gears introduces additional natural frequencies in the working range of the gearbox, determining noise and sometimes fatigue failures. Traditional techniques are not so useful for computing the dynamic overloads that this kind of gears generates, so a coupled MBS-FEM analysis is requested. In the present paper, the capabilities of gears analysis with the coupled MBS-FEM analysis are investigated with respect to gears with very thin geometry. Main results of the present paper are the demonstration of the validity of coupled MBS-FEM analysis in gear dynamic analysis and that, in such particular very flexible solution, also the web and the rim stiffnesses are fundamental in defining the gear dynamics and the load exchanged by the gears each other and with the other gearbox components
Advances in Mechanism and Machine Science, 2019
In this paper, enrichments of automotive steel wheels design procedure are presented. The princip... more In this paper, enrichments of automotive steel wheels design procedure are presented. The principal results are obtained using consolidated techniques as modal analysis and statistical approaches to estimate useful, but difficult to directly measure, system quantities. The methodology is applied to predict the local stiffening effect between the rim and the disk induced by the residual stress variation during the fitting procedure. The stiffening effect is related to components and assembly characteristics, such as masses, natural frequencies, generalised tolerances and uncertainties of elasto-plastic material properties and manufacturing process parameters. Components to assembly experimental modal analysis direct correlation is performed to identify the representative modes of the phenomena, while polynomial chaos expansion-based meta models developed upon experimental observations allow to extend the obtained results to component and assembly characteristics. A further improvement is analysed to extend the methodology to wheel-to-tyre interactions during fatigue tests allowing the indirect structure global stress estimation.
Shock and Vibration, 2020
Bearing is a crucial component of industrial equipment, since any fault occurring in this system ... more Bearing is a crucial component of industrial equipment, since any fault occurring in this system usually affects the functionality of the whole machine. To manage this problem, some currently available technologies enable the remote prognosis and diagnosis of bearings, before that faults compromise the system function and safety, respectively. A system for the in-service monitoring of bearing, to detect any inner fault or damage of components and material, allows preventing undesired machine stops. Moreover, it even helps in performing an out-monitoring action, aimed at revealing any anomalous behaviour of the system hosting bearings, through their dynamic response. The in-monitoring can be based on the vibration signal measurement and exploited to detect the presence of defects in material. In this paper, the orthogonal empirical mode decomposition is analysed and tested to investigate how it could be effectively exploited in a lean in-service monitoring operation and remote diagno...
Nonlinear Dynamics, Volume 1, 2017
In the literature, many models for depicting the gear mating dynamics are present. In addition, f... more In the literature, many models for depicting the gear mating dynamics are present. In addition, finite element techniques allow to perform highly representative engagement analysis, but with a high computational effort and in particular only after having defined a semi-definitive geometry. When a new gearbox is developed, its geometrical features are not completely defined, and highly refined finite element models cannot be used. On the other hand, performing parametric analysis at the early stages of the design process is mandatory to shorten the lead time. In this direction, an accurate parametric model of gear engagement, which requires a little computational effort, is an enabling technology. In the present paper, the Harmonic Balance Method is used to build a simple engagement model able to predict the dynamic effect in teeth contact and to investigate the contribution to gear dynamics due to actual static transmission error and the contact ratio. A particular emphasis is given to the actual contact ratio estimation and the relationship between the teeth stiffness and the dynamic transmission error. As principal result, the possibility to design teeth stiffness in order to minimize dynamic transmission error is investigated and HBM potential for reaching this goal is evaluated.
Procedia Structural Integrity, 2017
During their operation, modern aircraft engine components are subjected to increasingly demanding... more During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data.
SAE Technical Paper Series
Frattura ed Integrità Strutturale, 2015
Thin rimmed and webbed gears are used in particular applications to reduce systems weight. This k... more Thin rimmed and webbed gears are used in particular applications to reduce systems weight. This kind of gears need an accurate and fail safe design. As a matter of fact, a possible failure, due to bending fatigue, consists in crack nucleation and consequent growth, in particular in the tooth root zone. These cracks may propagate through the tooth or through the rim. Crack propagation direction is basically influenced by the wheel geometry parameters, above all the rim thickness. Studies available in literature emphasize three ranges for the backup ratio values, involving different behaviors. These ranges are related to the crack propagation paths; respectively through the tooth, through the rim and in an unforeseeable way. This last uncertainty zone depends on other parameters, related to both geometry and loading conditions. In this work the effect of wheel speed related to the bending load has been investigated. The investigation has been carried out by means of numerical models i...
In the literature, many models for depicting the gear mating dynamics are present. In addition, f... more In the literature, many models for depicting the gear mating dynamics are present. In addition, finite element techniques allow to perform highly representative engagement analysis, but with a high computational effort and in particular only after having defined a semi-definitive geometry. When a new gearbox is developed, its geometrical features are not completely defined, and highly refined finite element models cannot be used. On the other hand, performing parametric analysis at the early stages of the design process is mandatory to shorten the lead time. In this direction, an accurate parametric model of gear engagement, which requires a little computational effort, is an enabling technology. In the present paper, the Harmonic Balance Method is used to build a simple engagement model able to predict the dynamic effect in teeth contact and to investigate the contribution to gear dynamics due to actual static transmission error and the contact ratio. A particular emphasis is given...
Frattura ed Integrità Strutturale, 2014
Crack propagation in gears is a problem related not only to the life of the components, but also ... more Crack propagation in gears is a problem related not only to the life of the components, but also to the concept of failsafe design. Fail safe design means to design a component in order that, if a failure occurs, this may cause a “safe failure”. This aspect is very important above all in aerospace industry. As a matter of fact, in aerospace application, the need of reducing weight brings to produce gears with very thick rim and web. Considering thin rim gears, when a crack is nucleated near the tooth root, it may propagate through the tooth (causing the loss of the entire tooth or a portion of it) or the propagation may follow a path across the wheel diameter (causing the projection of big parts of the gear that may break the gearbox and may cause serious damage to the aircraft). The first failure mode is define as “failsafe failure” and the second one as “catastrophic failure” and of course has to be avoided. Designers need to have robust design criteria in order to predict crack p...
Springer eBooks, 2013
Creep and stress relaxation are known to be interrelated in linearly viscoelastic materials by an... more Creep and stress relaxation are known to be interrelated in linearly viscoelastic materials by an exact analytical expression. In this article, analytical interrelations are derived for nonlinearly viscoelastic materials which obey a single integral nonlinear superposition constitutive equation. The kernel is not assumed to be separable as a product of strain and time dependent parts. Superposition is fully taken into account within the single integral formulation used. Specific formulations based on power law time dependence and truncated expansions are developed. These are appropriate for weak stress and strain dependence. The interrelated constitutive formulation is applied to ligaments, in which stiffness increases with strain, stress relaxation proceeds faster than creep, and rate of creep is a function of stress and rate of relaxation is a function of strain. An interrelation was also constructed for a commercial diecast aluminum alloy currently used in small engine applications.
IOP Conference Series: Materials Science and Engineering, 2021
In the latest years many researcher focused on the possibility to foresee the failure of a mechan... more In the latest years many researcher focused on the possibility to foresee the failure of a mechanical system in the early stages in order to allow quick response times. Monitoring and diagnostics are at the base of those methodologies of predictive maintenance, which represents the standard for companies. Data acquired by monitoring systems are sometimes not sufficient to perform an effective diagnosis and to detect failures. In the present work the possibility of a defining a relation between the response of a system and the dimension of a defect causing the vibration is explored. Through a non-Hertzian contact model a roller bearing is studied and a correlation is sought between the size of the defect and the frequency content of the contact pressure time history. Resorting to a non-Hertzian approach enables the determination with good accuracy of the overpressures due to edge effects caused by the sudden change in curvature in presence of a defect. The estimation of the pressure ...
IOP Conference Series: Materials Science and Engineering, 2021
The search for propulsion systems of vehicles with lower environmental impact is focusing on syst... more The search for propulsion systems of vehicles with lower environmental impact is focusing on systems with exclusive or supplementary use of electric motors. In fully electric or hybrid vehicles, the electric power delivery is used not only to provide torque to the vehicle and the consequent movement of the vehicle, but also to transform the vehicle’s kinetic energy back into electrical energy for storage in batteries when the vehicle is downhill or it must be slowed down. Under normal operating conditions, even in urban usage, it is common to have sudden inversions of the power flow. This means that in a really short time the motor switches from delivering torque to receiving it. Normally the electric motor is not directly connected on the wheels, but a geared transmission is present. The change of torque from positive (motor) to negative (generator) causes a sudden change of the working conditions. This induces vibrational and durability problems on the gears. In the present paper,...
In aerospace gearboxes, very thin gears are used in order to reduce the weight of the system. The... more In aerospace gearboxes, very thin gears are used in order to reduce the weight of the system. The low stiff of such gears introduces additional natural frequencies in the working range of the gearbox, determining noise and sometimes fatigue failures. Traditional techniques are not so useful for computing the dynamic overloads that this kind of gears generates, so a coupled MBS-FEM analysis is requested. In the present paper, the capabilities of gears analysis with the coupled MBS-FEM analysis are investigated with respect to gears with very thin geometry. Main results of the present paper are the demonstration of the validity of coupled MBS-FEM analysis in gear dynamic analysis and that, in such particular very flexible solution, also the web and the rim stiffnesses are fundamental in defining the gear dynamics and the load exchanged by the gears each other and with the other gearbox components
Advances in Mechanism and Machine Science, 2019
In this paper, enrichments of automotive steel wheels design procedure are presented. The princip... more In this paper, enrichments of automotive steel wheels design procedure are presented. The principal results are obtained using consolidated techniques as modal analysis and statistical approaches to estimate useful, but difficult to directly measure, system quantities. The methodology is applied to predict the local stiffening effect between the rim and the disk induced by the residual stress variation during the fitting procedure. The stiffening effect is related to components and assembly characteristics, such as masses, natural frequencies, generalised tolerances and uncertainties of elasto-plastic material properties and manufacturing process parameters. Components to assembly experimental modal analysis direct correlation is performed to identify the representative modes of the phenomena, while polynomial chaos expansion-based meta models developed upon experimental observations allow to extend the obtained results to component and assembly characteristics. A further improvement is analysed to extend the methodology to wheel-to-tyre interactions during fatigue tests allowing the indirect structure global stress estimation.
Shock and Vibration, 2020
Bearing is a crucial component of industrial equipment, since any fault occurring in this system ... more Bearing is a crucial component of industrial equipment, since any fault occurring in this system usually affects the functionality of the whole machine. To manage this problem, some currently available technologies enable the remote prognosis and diagnosis of bearings, before that faults compromise the system function and safety, respectively. A system for the in-service monitoring of bearing, to detect any inner fault or damage of components and material, allows preventing undesired machine stops. Moreover, it even helps in performing an out-monitoring action, aimed at revealing any anomalous behaviour of the system hosting bearings, through their dynamic response. The in-monitoring can be based on the vibration signal measurement and exploited to detect the presence of defects in material. In this paper, the orthogonal empirical mode decomposition is analysed and tested to investigate how it could be effectively exploited in a lean in-service monitoring operation and remote diagno...
Nonlinear Dynamics, Volume 1, 2017
In the literature, many models for depicting the gear mating dynamics are present. In addition, f... more In the literature, many models for depicting the gear mating dynamics are present. In addition, finite element techniques allow to perform highly representative engagement analysis, but with a high computational effort and in particular only after having defined a semi-definitive geometry. When a new gearbox is developed, its geometrical features are not completely defined, and highly refined finite element models cannot be used. On the other hand, performing parametric analysis at the early stages of the design process is mandatory to shorten the lead time. In this direction, an accurate parametric model of gear engagement, which requires a little computational effort, is an enabling technology. In the present paper, the Harmonic Balance Method is used to build a simple engagement model able to predict the dynamic effect in teeth contact and to investigate the contribution to gear dynamics due to actual static transmission error and the contact ratio. A particular emphasis is given to the actual contact ratio estimation and the relationship between the teeth stiffness and the dynamic transmission error. As principal result, the possibility to design teeth stiffness in order to minimize dynamic transmission error is investigated and HBM potential for reaching this goal is evaluated.
Procedia Structural Integrity, 2017
During their operation, modern aircraft engine components are subjected to increasingly demanding... more During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data.
SAE Technical Paper Series
Frattura ed Integrità Strutturale, 2015
Thin rimmed and webbed gears are used in particular applications to reduce systems weight. This k... more Thin rimmed and webbed gears are used in particular applications to reduce systems weight. This kind of gears need an accurate and fail safe design. As a matter of fact, a possible failure, due to bending fatigue, consists in crack nucleation and consequent growth, in particular in the tooth root zone. These cracks may propagate through the tooth or through the rim. Crack propagation direction is basically influenced by the wheel geometry parameters, above all the rim thickness. Studies available in literature emphasize three ranges for the backup ratio values, involving different behaviors. These ranges are related to the crack propagation paths; respectively through the tooth, through the rim and in an unforeseeable way. This last uncertainty zone depends on other parameters, related to both geometry and loading conditions. In this work the effect of wheel speed related to the bending load has been investigated. The investigation has been carried out by means of numerical models i...
In the literature, many models for depicting the gear mating dynamics are present. In addition, f... more In the literature, many models for depicting the gear mating dynamics are present. In addition, finite element techniques allow to perform highly representative engagement analysis, but with a high computational effort and in particular only after having defined a semi-definitive geometry. When a new gearbox is developed, its geometrical features are not completely defined, and highly refined finite element models cannot be used. On the other hand, performing parametric analysis at the early stages of the design process is mandatory to shorten the lead time. In this direction, an accurate parametric model of gear engagement, which requires a little computational effort, is an enabling technology. In the present paper, the Harmonic Balance Method is used to build a simple engagement model able to predict the dynamic effect in teeth contact and to investigate the contribution to gear dynamics due to actual static transmission error and the contact ratio. A particular emphasis is given...
Frattura ed Integrità Strutturale, 2014
Crack propagation in gears is a problem related not only to the life of the components, but also ... more Crack propagation in gears is a problem related not only to the life of the components, but also to the concept of failsafe design. Fail safe design means to design a component in order that, if a failure occurs, this may cause a “safe failure”. This aspect is very important above all in aerospace industry. As a matter of fact, in aerospace application, the need of reducing weight brings to produce gears with very thick rim and web. Considering thin rim gears, when a crack is nucleated near the tooth root, it may propagate through the tooth (causing the loss of the entire tooth or a portion of it) or the propagation may follow a path across the wheel diameter (causing the projection of big parts of the gear that may break the gearbox and may cause serious damage to the aircraft). The first failure mode is define as “failsafe failure” and the second one as “catastrophic failure” and of course has to be avoided. Designers need to have robust design criteria in order to predict crack p...