Experimental Mechanics - a.y. 2016/2017
Period (Year/Semester): II/II
Required/expected prior knowledge: Nothing
Lecturers: Giovanni Pio Pucillo
The course follows the teachings of the Machine Design and provides the main knowledge both on the experimental techniques for the mechanical characterization of materials, structures, and machine components, as well as the techniques and the methodologies for the experimental analysis of the stress field in the material. Basic tools for the numerical simulation of the experimental activity are given as well. The theoretical part of the course is followed by a practical one in laboratory, where the student has the possibility to put into practice some analysis techniques studied in class.
Tables of contents:
Electrical resistance strain gauge: characteristics, calibration, sensitivity, strengthening effect, selection criteria, quarter bridge / half bridge / full bridge configuration, bridge's linearity errors. Strain measurement and analysis in plane and three-dimensional stress conditions; strain analysis for composite materials; residual stresses analysis. Semiconductor strain gauges. - Transmission and reflection photoelasticity: photoelastic effect, polariscope optics, photoelastic data analysis (isostatics determination and stress separation, transfer of results from the model to the prototype), three-dimensional photoelasticity, frozen stress technique, experimental techniques, digital photoelasticity. - Brittle coating method: background of brittle coatings, coating failure, calibration, isoentatics, experimental techniques, physical characteristics of commercial brittle-coating materials. Geometrical Moiré, projection Moiré, shadow Moiré technique. Holographic interferometry: theory and experimental techniques, fringes interpretation (plane and three-dimensional conditions), metrological applications, automatic data acquisition and data elaboration. Speckle methods: speckle effect, objective and subjective speckle, techniques (speckle photography and interferometry), automatic data acquisition and data elaboration. Validation and homologation tests: technical specifications and standards test methods, test fixtures and test facilities, equipments and instrumentation, sensor calibration.
Practical and theoretical exercitation and lessons. Data acquisition unit managing and programming. Guided tours at the R&D division of industries and/or external laboratories.
Textbooks and learning aids:
Augusto Ajovalasit, "Analisi Sperimentale delle Tensioni con la Fotomeccanica. Fotoelasticità, Moiré, Olografia, Speckle, Correlazione Immagini". ARACNE editrice S.r.l, 2009.
Augusto Ajovalasit, "Analisi Sperimentale delle Tensioni con gli Estensimetri Elettrici a Resistenza". ARACNE editrice S.r.l, 2008.
A. Bray, V. Vicentini: "Meccanica Sperimentale" Volumi 1 e 2. Levrotto e Bella, 1975.
Assessment will be written and oral. Laboratory test.