F. Frendo - Academia.edu (original) (raw)

Papers by F. Frendo

Procedia Structural Integrity

International Journal of Mechanical Sciences

Procedia Structural Integrity

Procedia Structural Integrity, 2022

In this paper several multibody models of a tilting four wheeler are described. The models were&l... more In this paper several multibody models of a tilting four wheeler are described. The models were<br> conceived in the framework of the European Project RESOLVE (Range of Electric SOlution for Lcategory<br> VEhicles).<br> In the models, the actual masses and inertia of the real vehicle parts were implemented, as well as the<br> suspension and steering system characteristics and the tire to ground actions. The rider was implemented<br> through the actions exerted on the handlebar, computed on the basis of purposely developed controllers.<br> Several simulations were carried out reproducing reference maneuvers in order to get the loads on<br> structural components and the actions of the rider on the handlebar. The effect of the longitudinal forces<br> on vehicle dynamics was also investigated (torque vectoring).<br> The results confirmed the prototype feasibility and its similarity to conventional two wheelers.

IOP Conference Series: Materials Science and Engineering, 2021

The present work presents a multifunctional structure for space engineering application part of t... more The present work presents a multifunctional structure for space engineering application part of the TOPDESS project, funded by ESA. The main aim of the project is the design of a thermal control device able to deploy through passive actuation. A combined device has been designed, made up of a Pulsating Heat Pipe (PHP) foldable heat exchanger and Shape Memory Alloy (SMA) wire. The deployment of the SMA wire is conceived to be controlled by thermal contact with the heat source and by conduction along the wire. Since the heat sources are lumped and the wire is subject to convection, a temperature gradient develops along the wire. A monodimensional mode able to predict the behavior of an SMA wire subjected to a spatial temperature gradient, is presented in this paper. The results show that the system can carry out folding and unfolding cycles with rotation angles greater than 80° only if the wire is subjected to uniform temperature distribution; in the case of temperature gradient, the ...

Thermal Spray 1998: Proceedings from the International Thermal Spray Conference, 1998

The coefficient of thermal expansion (CTE) of a NiCoCrAlY coating was investigated in this work. ... more The coefficient of thermal expansion (CTE) of a NiCoCrAlY coating was investigated in this work. The CTE was inferred from the measured length variations of coated prismatic symmetric specimens (i.e. having the coating on two opposite surfaces) at various temperature increments. The elongation of the specimen was evaluated from the relative positions of two markers, which was recorded during the test by a CCD video camera; analysis with subpixeling technique allowed high resolution in the dilatation measurements. Analytical relationships used to determine the coating's CTE were based on the simple multilayer beam model; the temperature dependent elastic moduli of the layers had been determined by four point bend test in a previous work. Coated specimens were employed having different substrate thicknesses in order to check the accuracy of measurements.

Mechanism and Machine Theory, 2022

Welding in the World, 2021

Mechanism and Machine Theory, 2020

The present paper is an extension of a previously published paper by the authors, where the "brus... more The present paper is an extension of a previously published paper by the authors, where the "brush" model was adopted for the contact stresses between the belt and pulleys. In this paper, the axial stiffness of the belt is introduced, while in previous work, particularly suited for belt with stiff reinforcement fibers, the belt was assumed to be inextensible. The complete set of equations is derived in steady state conditions and the relationship between belt tension and belt speed is introduced based on the continuity condition. The belt tension can be obtained by solving a second order differential equation, for which a closed form solution is given. A numerical procedure is, however, necessary for determining the solution of a given transmission with assigned rotational speed at the driving pulley and resistant moment at the driven pulley. It is shown how the contact angle at which stick-slip phenomenon may occur is influenced by the belt stiffness and the way the transmission effiency is reduced. Allowing to analyze the mechanics of flat belt transmission, the model can be considered a useful tool for the designer.

Journal of Physics: Conference Series, 2016

Since nowadays the NVH performance of vehicles has become an important priority, the noise radiat... more Since nowadays the NVH performance of vehicles has become an important priority, the noise radiating from brakes is considered a source of considerable passenger discomfort and dissatisfaction. Creep groan and squeal that show up with annoying vibrations and noise in specific frequency ranges are typical examples of self-excited brake vibrations caused by the stick-slip effect, the former, by the mode coupling of brake disc and friction pads or calliper, the latter. In both cases, the friction coefficient, which depends, among other factors, on the morphology of the mating surfaces and on the operating conditions, is a fundamental parameter but not the only one for the occurrence of the vibratory phenomena. Finite element complex eigenvalue parametric analyses were performed on a disc brake assembly to evaluate propensity to dynamic instability of brakes with multiple pads, as in railway brakes, as a function of the number of pads, pad shape and size, and material parameters.

Engineering Fracture Mechanics

Fatigue & Fracture of Engineering Materials & Structures, 2017

generation algorithm available in the numerical code. To speed-up the analyses no check of the si... more generation algorithm available in the numerical code. To speed-up the analyses no check of the size and no check of the difference between the lengths of adjacent edges of an element are required; indeed, approximations are all included in the scatter band of the PSM. The following new part has been added to the revised manuscript to clarify this point: "The finite element size d has been intentionally taken as the 'global element size' input by the FE analyst before running the free mesh generation algorithm available in the FE code. Obviously, the edge lengths of the actually generated finite elements will fulfil the prescribed size d only approximately. Nevertheless, the average FE size d has been adopted in Eqs (3) and (4), the effects of the variability of the FE size in the vicinity of the V-notch tip being included in the scatter band of K FE * and K FE ** ." 3. Section 4.2 describes the loading in the shear case, mentioning prescribed displacements which correspond to a gross shear stress. The relation applies to an absent crack. But doesn't a crack weaken the plate so that this relation changes is such a case? Please clarify. Yes, the crack alters the uniform gross shear stress existing in the un-cracked case. In the crack case it is just a reference stress: please note that the same reference stress has been adopted to evaluate the exact SIF K 2 (using extremely refined FE meshes) and the sliding FE peak stress τ ΙΙ,peak (using coarse meshes according to the PSM). The exact SIF K 2 and the sliding peak stress τ ΙΙ,peak evaluated by using the same loading condition are input in Eq. (6) in order to calculate the normalised SIF K FE **. This has been clarified in the section 5.2 of the revised manuscript. 4. In Section 7.4 it is mentioned that the default options are highlighted in Tables 8 and 9 (also in the table captions). Do you mean 'default options indicated'? Thanks. Yes, we mean the 'default options indicated', we have modified both text and Table captions accordingly.

Meccanica, 2013

Since, nowadays, the NVH performance of a vehicle is one of the most important priorities for the... more Since, nowadays, the NVH performance of a vehicle is one of the most important priorities for the market, the noise radiating from disc brakes is considered a source of considerable discomfort and customer dissatisfaction. Squeal is an example of noise, caused by vibrations induced by friction forces, in which the vibration modes of the brake disc are coupled to those of the friction pads or of the caliper. In this work a case study, in which the squeal phenomenon was detected after changing the supplier of the disc pads, is presented. A test bench was purposely developed to investigate the squeal phenomenon; tests at different rotating speeds and pressures in the brake circuit were carried out employing different friction pads. The experimental apparatus appeared capable of reproducing the phenomenon observed in real practice and to investigate the effect of operating parameters and different components on the onset of instability. Friction tests and geometric analysis of the friction pads were also carried out to complete the investigation. At the same time, a finite element (FE) complex eigenvalue parametric analysis was performed on the brake assembly. The different propensity of the pads to squeal was attributed to differences in their geometry and in their friction coefficients. The FE analysis, confirmed the experimental observations and indicated possible design improvements to increase the stability of the system.

IOP Conference Series: Materials Science and Engineering, 2021

The mechanics of power transmission is usually modeled by two different theories: the creep theor... more The mechanics of power transmission is usually modeled by two different theories: the creep theory and the shear theory. Recently, the authors introduced an alternative theory based on the brush model, which allows to compute the tangential stress distribution along the winding arc of pulleys. The brush model is able to predict the speed loss along the driving and driven pulley as a function of the transmission parameters (e.g. pre-load, friction, pulley radii etc.) and the operating parameters (i.e. angular speed and resistant torque). In addition, the energy efficiency of the system is obtained by knowing the speed loss and the energy dissipation; this contribution can be subdivided into energy loss due to friction and energy loss due to the non-recoverable elastic deformation of the bristle. In the present paper, using the previously developed model, a sensitivity analysis aimed at mapping the transmission capabilities as a function of geometry and operating parameters is propose...

IOP Conference Series: Materials Science and Engineering

This work deals with the development of a simplified and time-efficient phenomenological model fo... more This work deals with the development of a simplified and time-efficient phenomenological model for chain transmissions efficiency. Firstly, a complete multibody model for a final transmission of a motorcycle is developed in MSC Adams View environment, and is properly validated in terms of efficiency with experimental tests on a real chain system. Results from multibody simulations are used to develop a new analytical model, that relates all the main operating and geometry parameters of the transmission system to the transmission efficiency with simple relations. In particular, the influence of the polygonal effect on system efficiency is investigated, finding a relationship with the angle of the sprockets pitch polygon. A new parameter, called chain tension efficiency, is introduced to model the distribution of losses within the system. A linear relationship between this parameter and the number of sprockets teeth and with the system efficiency was assumed and validated, with good r...

Procedia Structural Integrity

Mechanism and Machine Theory

Procedia Structural Integrity

International Journal of Mechanical Sciences

Procedia Structural Integrity

Procedia Structural Integrity, 2022

In this paper several multibody models of a tilting four wheeler are described. The models were&l... more In this paper several multibody models of a tilting four wheeler are described. The models were<br> conceived in the framework of the European Project RESOLVE (Range of Electric SOlution for Lcategory<br> VEhicles).<br> In the models, the actual masses and inertia of the real vehicle parts were implemented, as well as the<br> suspension and steering system characteristics and the tire to ground actions. The rider was implemented<br> through the actions exerted on the handlebar, computed on the basis of purposely developed controllers.<br> Several simulations were carried out reproducing reference maneuvers in order to get the loads on<br> structural components and the actions of the rider on the handlebar. The effect of the longitudinal forces<br> on vehicle dynamics was also investigated (torque vectoring).<br> The results confirmed the prototype feasibility and its similarity to conventional two wheelers.

IOP Conference Series: Materials Science and Engineering, 2021

The present work presents a multifunctional structure for space engineering application part of t... more The present work presents a multifunctional structure for space engineering application part of the TOPDESS project, funded by ESA. The main aim of the project is the design of a thermal control device able to deploy through passive actuation. A combined device has been designed, made up of a Pulsating Heat Pipe (PHP) foldable heat exchanger and Shape Memory Alloy (SMA) wire. The deployment of the SMA wire is conceived to be controlled by thermal contact with the heat source and by conduction along the wire. Since the heat sources are lumped and the wire is subject to convection, a temperature gradient develops along the wire. A monodimensional mode able to predict the behavior of an SMA wire subjected to a spatial temperature gradient, is presented in this paper. The results show that the system can carry out folding and unfolding cycles with rotation angles greater than 80° only if the wire is subjected to uniform temperature distribution; in the case of temperature gradient, the ...

Thermal Spray 1998: Proceedings from the International Thermal Spray Conference, 1998

The coefficient of thermal expansion (CTE) of a NiCoCrAlY coating was investigated in this work. ... more The coefficient of thermal expansion (CTE) of a NiCoCrAlY coating was investigated in this work. The CTE was inferred from the measured length variations of coated prismatic symmetric specimens (i.e. having the coating on two opposite surfaces) at various temperature increments. The elongation of the specimen was evaluated from the relative positions of two markers, which was recorded during the test by a CCD video camera; analysis with subpixeling technique allowed high resolution in the dilatation measurements. Analytical relationships used to determine the coating's CTE were based on the simple multilayer beam model; the temperature dependent elastic moduli of the layers had been determined by four point bend test in a previous work. Coated specimens were employed having different substrate thicknesses in order to check the accuracy of measurements.

Mechanism and Machine Theory, 2022

Welding in the World, 2021

Mechanism and Machine Theory, 2020

The present paper is an extension of a previously published paper by the authors, where the "brus... more The present paper is an extension of a previously published paper by the authors, where the "brush" model was adopted for the contact stresses between the belt and pulleys. In this paper, the axial stiffness of the belt is introduced, while in previous work, particularly suited for belt with stiff reinforcement fibers, the belt was assumed to be inextensible. The complete set of equations is derived in steady state conditions and the relationship between belt tension and belt speed is introduced based on the continuity condition. The belt tension can be obtained by solving a second order differential equation, for which a closed form solution is given. A numerical procedure is, however, necessary for determining the solution of a given transmission with assigned rotational speed at the driving pulley and resistant moment at the driven pulley. It is shown how the contact angle at which stick-slip phenomenon may occur is influenced by the belt stiffness and the way the transmission effiency is reduced. Allowing to analyze the mechanics of flat belt transmission, the model can be considered a useful tool for the designer.

Journal of Physics: Conference Series, 2016

Since nowadays the NVH performance of vehicles has become an important priority, the noise radiat... more Since nowadays the NVH performance of vehicles has become an important priority, the noise radiating from brakes is considered a source of considerable passenger discomfort and dissatisfaction. Creep groan and squeal that show up with annoying vibrations and noise in specific frequency ranges are typical examples of self-excited brake vibrations caused by the stick-slip effect, the former, by the mode coupling of brake disc and friction pads or calliper, the latter. In both cases, the friction coefficient, which depends, among other factors, on the morphology of the mating surfaces and on the operating conditions, is a fundamental parameter but not the only one for the occurrence of the vibratory phenomena. Finite element complex eigenvalue parametric analyses were performed on a disc brake assembly to evaluate propensity to dynamic instability of brakes with multiple pads, as in railway brakes, as a function of the number of pads, pad shape and size, and material parameters.

Engineering Fracture Mechanics

Fatigue & Fracture of Engineering Materials & Structures, 2017

generation algorithm available in the numerical code. To speed-up the analyses no check of the si... more generation algorithm available in the numerical code. To speed-up the analyses no check of the size and no check of the difference between the lengths of adjacent edges of an element are required; indeed, approximations are all included in the scatter band of the PSM. The following new part has been added to the revised manuscript to clarify this point: "The finite element size d has been intentionally taken as the 'global element size' input by the FE analyst before running the free mesh generation algorithm available in the FE code. Obviously, the edge lengths of the actually generated finite elements will fulfil the prescribed size d only approximately. Nevertheless, the average FE size d has been adopted in Eqs (3) and (4), the effects of the variability of the FE size in the vicinity of the V-notch tip being included in the scatter band of K FE * and K FE ** ." 3. Section 4.2 describes the loading in the shear case, mentioning prescribed displacements which correspond to a gross shear stress. The relation applies to an absent crack. But doesn't a crack weaken the plate so that this relation changes is such a case? Please clarify. Yes, the crack alters the uniform gross shear stress existing in the un-cracked case. In the crack case it is just a reference stress: please note that the same reference stress has been adopted to evaluate the exact SIF K 2 (using extremely refined FE meshes) and the sliding FE peak stress τ ΙΙ,peak (using coarse meshes according to the PSM). The exact SIF K 2 and the sliding peak stress τ ΙΙ,peak evaluated by using the same loading condition are input in Eq. (6) in order to calculate the normalised SIF K FE **. This has been clarified in the section 5.2 of the revised manuscript. 4. In Section 7.4 it is mentioned that the default options are highlighted in Tables 8 and 9 (also in the table captions). Do you mean 'default options indicated'? Thanks. Yes, we mean the 'default options indicated', we have modified both text and Table captions accordingly.

Meccanica, 2013

Since, nowadays, the NVH performance of a vehicle is one of the most important priorities for the... more Since, nowadays, the NVH performance of a vehicle is one of the most important priorities for the market, the noise radiating from disc brakes is considered a source of considerable discomfort and customer dissatisfaction. Squeal is an example of noise, caused by vibrations induced by friction forces, in which the vibration modes of the brake disc are coupled to those of the friction pads or of the caliper. In this work a case study, in which the squeal phenomenon was detected after changing the supplier of the disc pads, is presented. A test bench was purposely developed to investigate the squeal phenomenon; tests at different rotating speeds and pressures in the brake circuit were carried out employing different friction pads. The experimental apparatus appeared capable of reproducing the phenomenon observed in real practice and to investigate the effect of operating parameters and different components on the onset of instability. Friction tests and geometric analysis of the friction pads were also carried out to complete the investigation. At the same time, a finite element (FE) complex eigenvalue parametric analysis was performed on the brake assembly. The different propensity of the pads to squeal was attributed to differences in their geometry and in their friction coefficients. The FE analysis, confirmed the experimental observations and indicated possible design improvements to increase the stability of the system.

IOP Conference Series: Materials Science and Engineering, 2021

The mechanics of power transmission is usually modeled by two different theories: the creep theor... more The mechanics of power transmission is usually modeled by two different theories: the creep theory and the shear theory. Recently, the authors introduced an alternative theory based on the brush model, which allows to compute the tangential stress distribution along the winding arc of pulleys. The brush model is able to predict the speed loss along the driving and driven pulley as a function of the transmission parameters (e.g. pre-load, friction, pulley radii etc.) and the operating parameters (i.e. angular speed and resistant torque). In addition, the energy efficiency of the system is obtained by knowing the speed loss and the energy dissipation; this contribution can be subdivided into energy loss due to friction and energy loss due to the non-recoverable elastic deformation of the bristle. In the present paper, using the previously developed model, a sensitivity analysis aimed at mapping the transmission capabilities as a function of geometry and operating parameters is propose...

IOP Conference Series: Materials Science and Engineering

This work deals with the development of a simplified and time-efficient phenomenological model fo... more This work deals with the development of a simplified and time-efficient phenomenological model for chain transmissions efficiency. Firstly, a complete multibody model for a final transmission of a motorcycle is developed in MSC Adams View environment, and is properly validated in terms of efficiency with experimental tests on a real chain system. Results from multibody simulations are used to develop a new analytical model, that relates all the main operating and geometry parameters of the transmission system to the transmission efficiency with simple relations. In particular, the influence of the polygonal effect on system efficiency is investigated, finding a relationship with the angle of the sprockets pitch polygon. A new parameter, called chain tension efficiency, is introduced to model the distribution of losses within the system. A linear relationship between this parameter and the number of sprockets teeth and with the system efficiency was assumed and validated, with good r...

Procedia Structural Integrity

Mechanism and Machine Theory