gianluca rossi - Academia.edu (original) (raw)

Papers by gianluca rossi

In fluid-dynamic phenomena analisys the boundary layer plays a fundamental role It also affects t... more In fluid-dynamic phenomena analisys the boundary layer plays a fundamental role It also affects the drag and lift force of a body immersed in a fluid. Reynolds analogy introduces the possibility to use high sensitivity thermographic systems. Such approaches can be used to analyse the distribution of shear stress on the surface of solid bodies immersed into a fluid through temperature distribution. Temperature field can be acquired with the aid of a thermographic system on the surface of a solid body invested by a flow. Temperature distribution depends on many combined effects, such as: conversion of kinetic energy of the flow into thermal energy, flow temperature variation in time and space, convection heat transfer phenomena between flow and body, conduction phenomena inside the body, and radiation heath exchange. A numerical approach was used to validate the proposed procedure. A transient simulation with increasing inlet fluid temperature was carried out to evaluate the thermal exchange between the airstream and the body. The effect of the different thermal exchange due to the local flow peculiarity is modelled.

Because of the continuous evolution of the market in terms of quality and performance, the mechan... more Because of the continuous evolution of the market in terms of quality and performance, the mechanical production industry is subjected to more and more pressing technological challenges. In this frame the use of advanced measurement technique as the thermoelasticity, allows the engineers to have a fast and reliable tool of experimental investigation, optimization and validation of the FEM models of those critical parts as for example parts of car frames. In this work it is shown how the thermoelastic measurement technique can be used to optimize mechanical components, as method of experimental investigation and as technique of validation of numerical models. The measurement technique developed for this purpose is described together with the calibration method used in the test benches normally used for fatigue testing and qualification of these mechanical components. The results obtained show a very good deal with FEM models and also the possibility to experimentally identify the concentration levels of stress in critical parts with a very high spatial resolution and testing the effective geometry and structure material.

arXiv (Cornell University), May 9, 2022

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In this work the performances of three different techniques for 3D scanning have been investigate... more In this work the performances of three different techniques for 3D scanning have been investigated. In particular two commercial tools (smartphone camera and iPad Pro LiDAR) and a structured light scanner (Go!SCAN 50) have been used for the analysis. First of all, two different subjects have been scanned with the three different techniques and the obtained 3D model were analysed in order to evaluate the respective reconstruction accuracy. A case study involving a child was then considered, with the main aim of providing useful information on performances of scanning techniques for clinical applications, where boundary conditions are often challenging (i.e., non-collaborative patient). Finally, a full procedure for the 3D reconstruction of a human shape is proposed, in order to setup a helpful workflow for clinical applications.

A comparison of commercial 3D photo modelling software applications is presented. Starting from t... more A comparison of commercial 3D photo modelling software applications is presented. Starting from the simple acquisition of digital images, and based on the principles of photogrammetry, photo modelling represents a user-friendly and economical way to digitally preserve and three-dimensionally reproduce cultural heritage objects. The aim of this research is to evaluate the potential offered by the technique by reviewing a range of commercial and opensource software applications and making a comparison with reference data points obtained from a structured light 3D scanner. A marble artefact was selected from the collection of the Galleria Nazionale dell'Umbria di Perugia (Italy) as a test case for the analytical comparison of these two optical techniques.

Measurement, Oct 1, 2018

Photomodelling is an innovative, economical and fast technique based on the same principles of ph... more Photomodelling is an innovative, economical and fast technique based on the same principles of photogrammetry, which leads to the creation of 3-dimensional models starting from the simple acquisition of photographs. The aim of this paper is to define performances and metrological characteristics of this new technique and to understand the full potential offered by point cloud processing software. The analytical comparison considers a structured light 3D scanning system Creaform Go Scan 50 with metrological certification as a reference, in order to verify the accuracy and precision of photomodelling, using a modified function of the ICP algorithm and spatial, volumetric and superficial comparison criteria.

In this paper measurement of vibrations on a test case, a simple typical bending beam on an elect... more In this paper measurement of vibrations on a test case, a simple typical bending beam on an electro dynamical exciter, are performed by using a high resolution and sufficiently fast thermocamera. Excitation of the beam has been performed by band-limited noise and response is measured in terms of temperature time history on its surface by the recorded thermal film. Temperature time evolution on the beam surface is also related to stress time evolution according to the thermoelastic principle. By developing a special data processing software of the thermal film the possibility to get the operational deflection mode shapes of the beam is clearly demonstrated. The possibility to measure a new proposed transfer function named stressance (ratio between exciting force and resulting stress) on the different point of the beam surface is proposed.

Proceedings of SPIE, Jun 19, 2006

The application of both scanning laser vibrometry and thermoelasticity for measurement of stress ... more The application of both scanning laser vibrometry and thermoelasticity for measurement of stress and strain fields on mechanical components is proposed. A theoretical approach on both the measurement principles is illustrated and an application to a practical case, as an automotive fan blade, is described. The problem of the fan blade failure is tightly due to the force amplitude and frequency, that are applied in working condition; it is, therefore, important, to know the blade resonance frequencies and the mode shapes. For this reason, the measurement techniques, based on scanning laser Doppler vibrometer, give the chance to quickly perform an experimental modal analysis with high accuracy and spatial resolution and to obtain the structure's mode shapes. In the same time, it is important to assess the stress distribution level on the blade associated to every mode shape. Measurement techniques, that apply thermoelastic principle, allow to quickly determine the blade stress pattern at each load frequency. It is, therefore, possible to establish the stress pattern corresponding to the mode shape and predict the fatigue life of the component.

Materials, Jul 8, 2017

The article presents a hybrid monitoring technique for the measurement of the deformation field. ... more The article presents a hybrid monitoring technique for the measurement of the deformation field. The goal is to obtain information about crack propagation in existing structures, for the purpose of monitoring their state of health. The measurement technique is based on the capture and analysis of a digital image set. Special markers were used on the surface of the structures that can be removed without damaging existing structures as the historical masonry. The digital image analysis was done using software specifically designed in Matlab to follow the tracking of the markers and determine the evolution of the deformation state. The method can be used in any type of structure but is particularly suitable when it is necessary not to damage the surface of structures. A series of experiments carried out on masonry walls of the Oliverian Museum (Pesaro, Italy) and Palazzo Silvi (Perugia, Italy) have allowed the validation of the procedure elaborated by comparing the results with those derived from traditional measuring techniques.

In this study, the effect of Friction Stir Welding on a 6061 aluminium alloy reinforced with 20% ... more In this study, the effect of Friction Stir Welding on a 6061 aluminium alloy reinforced with 20% of alumina particles metal matrix composite was analysed. The sheets were joined by employing a tool rotating at a speed of 700 RPM and a welding speed of 250 mm/min. Optical and scanning electron microscopy observations performed on different zones of the FSW joints cross section revealed the different nugget structures: the thermo-mechanical affected zone and the heat affected zones thanks to the difference in reinforcing particles dimensions as a consequence of the friction process. After FSW the material was aged in a 3.5% NaCl + 0.3 g/1 H 2 0 2 solution for 1, 10 and 90 days. Being a non-contact technique and allowing real-time analysis unlike most investigating means used in this field, the thermoelastic stress technique was applied with success to the study of crack formation and propagation of friction stir welded MMC sheets during cyclic fatigue tests. Fatigue tests were carried out under the axial total stress-amplitude control mode with R=o m j n /o m ax = 0.1 using a resonant electro-mechanical testing machine (TESTRONICTM 50± 25 KN by RUMUL. SU1). All the mechanical tests were performed on as-FSW and aged samples up to failure. The TSA