Papers by Cristiana Delprete
ASM International eBooks, May 15, 2022
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Journal of manufacturing and materials processing, Feb 1, 2023
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HAL (Le Centre pour la Communication Scientifique Directe), May 16, 2022
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2020 IEEE International Symposium on Systems Engineering (ISSE), 2020
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Polymer, 2022
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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 ...
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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,...
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2019 22nd International Conference on the Computation of Electromagnetic Fields (COMPUMAG), 2019
Vibrations of a three degrees of freedom mechanical structure are attenuated using a magnetic dam... more Vibrations of a three degrees of freedom mechanical structure are attenuated using a magnetic damper, obtained by coupling a conductive structure with a magnetic field generated by permanent magnets. The magnetic dissipations are experimentally investigated focusing on their nonlinearity with respect to frequency and amplitude of oscillations. The system exhibits two types of nonlinearities: one proper of the mechanical system and one of due to the magnetic coupling. The availability of an electromagnetic-motional model allows for the separation of these two effects. A frequency domain model to describe the magneto-mechanical interaction under harmonic excitation is developed by means of a partial element equivalent circuit of the conductive parts. The restitution magnetic force model is then introduced in the numerical model of the system. Results obtained by simulations are validated versus experimental measurements on the three degrees of freedom structure.
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Magnetic damped vibrations are obtained by coupling a conductive structure with a magnetic field.... more Magnetic damped vibrations are obtained by coupling a conductive structure with a magnetic field. The induced damping force characteristic depends upon displacement and velocity. When the magnetic field is generated by permanent magnets, a good model of the damping characteristic requires the estimation of the eddy currents induced in the conductive parts and subsequently of the resulting Lorentz force acting on them. This force is unfortunately nonlinear as its magnitude depends both on frequency and amplitude of oscillations. Considering by hypothesis a harmonic motion of the system, a simulation of the magneto-dynamic phenomenon is performed by means of a partial element equivalent circuit of the conductive parts. The force characteristic is then used to fit a sinusoidal input describing function approximation. Results obtained by simulations are validated versus experimental measurements on a three degrees of freedom structure.
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Scienza, tecnica, sport e passione: gli ingredienti del record italiano di velocita a pedali conq... more Scienza, tecnica, sport e passione: gli ingredienti del record italiano di velocita a pedali conquistato a settembre dal Team Policumbent del Politecnico di Torino
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Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2021
Theory of Critical Distances (TCD) collects several methods adopted in failure prediction of comp... more Theory of Critical Distances (TCD) collects several methods adopted in failure prediction of components provided with stress concentration features. The idea of evaluating stress effect in a zone rather than in a single point was proposed decades ago but, only thanks to relatively recent works, TCD concepts showed to be a successful extension of Linear Elastic Fracture Mechanics (LEFM), able to assess strength and fatigue life. The increasing computational power has made Finite Element Method (FEM) widespread, hence stress fields can be easily extracted and used as input data for fatigue post-processing and durability analyses. In this scenario, TCD reveals as a powerful tool which, thanks to the introduction of a single material parameter (critical distance, [Formula: see text]), integrates classical fracture models by considering the presence of microscale phenomena acting in fracture process. In this sense, TCD behaves as a link between continuum mechanics and LEFM. Modalities an...
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Procedia Structural Integrity, 2019
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Procedia Structural Integrity, 2019
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Journal of Engineering, Design and Technology, 2020
Purpose The implementation of project-based learning (PBL) activities in the curricula of enginee... more Purpose The implementation of project-based learning (PBL) activities in the curricula of engineering students has become a consolidated method to improve their skills. The purpose of this paper is to share the experience acquired by the authors from a decennial case-study on a student team PBL activity focused on design and development of human-powered vehicles (HPVs). A review of the project evolution, boundary constraints and management choices could provide inspiration and suggestions to faculty staff that would like to set-up similar experiences for engineering students in their universities. Design/methodology/approach A student team was funded by the authors in 2008 to gather engineering students interested in design and construction of HPVs. In the past decade, the team has grown from 10 up to 60 students enrolled per year and stimulated to develop a range of HPV designs for sports and mobility. The project management evolved as a consequence to com ply with the growing ambi...
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International Journal of Automotive Composites, 2017
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Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2019
The paper presents and discusses a low-cycle fatigue life prediction energy-based model. The mode... more The paper presents and discusses a low-cycle fatigue life prediction energy-based model. The model was applied to a commercial cast iron automotive exhaust manifold. The total expended energy until fracture proposed by the Skelton model was modified by means of two coefficients which take into account of the effects of mean stress and/or mean strain, and the presence of high temperature. The model was calibrated by means of experimental tests developed on Fe–2.4C–4.6Si–0.7Mo–1.2Cr high-temperature-resistant ductile cast iron. The thermostructural transient analysis was developed on a finite element model built to overtake confidentiality industrial restrictions. In addition to the commercial exhaust manifold, the finite element model considers the bolts, the gasket, and a cylinder head simulacrum to consider the corresponding thermal and mechanical boundary conditions. The life assessment performance of the energy-based model with respect the cast iron specimens was compared with th...
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Procedia Structural Integrity, 2017
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Sports Engineering, 2017
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Papers by Cristiana Delprete