Mechanical and thermal measurements
Academic Year 2023/2024 - Teacher: Fabio Raffaele Emilio An LO SAVIOExpected Learning Outcomes
The course aims to provide basic measurement knowledge and an accurate analysis of transducers. Both static and dynamic analysis of the performance of measurement chains are addressed. The main types of transducers are analyzed in detail with the discussion of metrological parameters. The student engineer will be instructed on the most significant aspects of measuring devices and methods of detecting the main mechanical and thermal quantities. The course also includes practical exercises in the laboratory and in the classroom with examples of the use of sensors and data analysis.
Course Structure
The course will be structured as follows: Logical foundations of measurement operations. Concepts of magnitude and measurement. Systems of units of measurement: CGS, MKS, Technical System, English System, International System. Dimensional equations. Measurement schemes: direct, indirect, zeroing and deviation instruments. Theory of measurement systems: purpose of measurement; functional analysis of an instrument; active and passive transducers; information flow in the measurement chain; errors due to disturbance quantities. Statistical analysis for the a posteriori evaluation of uncertainties: representation of errors; best estimate, standard deviation and standard deviation of the mean; Gaussian curve; error propagation; Chauvenet criterion; least squares method (linear regression), covariance and correlation. Static performance of instruments: static calibration; metrological characteristics and causes of error of the instruments: sensitivity; linearity; repeatability; accuracy; precision; fineness (insertion error); hysteresis; mobility and resolution. Dynamic instrument performance: response to time-varying signals; bandwidth; instruments of 0-, 1- and 2-order; transfer function; dynamic calibration. Analog circuits and instruments: Wheatstone bridge; potentiometric circuit; galvanometer; oscilloscope. Measurement of the main mechanical quantities: length and displacement; speed and range; vibration and acceleration; mass and strength; temperature; mechanical power; pressure. Stress-strain analysis: local methods (strain measurement).
Required Prerequisites
To better understand the contents of Mechanical and Thermal Measurements, at the beginning of the teaching activities the student should possess knowledge ("cultural" propaedeutics) of mathematical analysis, physics, electrical engineering and construction science. There are no "formal" preparatory requirements.
Attendance of Lessons
Mandatory attendance.
Detailed Course Content
Logical foundations of measurement operations. Concepts of quantity and measurement. Systems of units: CGS, MKS, Technical System, English System, International System. Dimensional equations. Measurement schemes: direct, indirect, zeroing and deviation instruments. Theory of measurement systems: purpose of measurement; functional analysis of an instrument; active and passive transducers; information flow in the measurement chain; errors due to disturbance quantities. Statistical analysis for the a posteriori evaluation of uncertainties: representation of errors; best estimate, standard deviation and standard deviation of the mean; Gaussian curve; error propagation; Chauvenet criterion; least squares method (linear regression), covariance and correlation. Static performance of instruments: static calibration; metrological characteristics and causes of error of the instruments: sensitivity; linearity; repeatability; accuracy; precision; finess (insertion error); hysteresis; mobility and resolution. Dynamic instrument performance: response to time-varying signals; bandwidth; instruments of 0-, 1- and 2-order; transfer function; dynamic calibration. Analog circuits and instruments: Wheatstone bridge; potentiometric circuit; galvanometer; oscilloscope. Measurement of the main mechanical quantities: length and displacement; speed and range; vibration and acceleration; mass and strength; temperature; mechanical power; pressure. Stress-strain analysis: local methods (strain measurement).
Textbook Information
- E. O. Doebelin, Strumenti e metodi di misura, McGraw-Hill. Milano.
- A. Ajovalasit, Analisi delle sollecitazioni: estensimetria. Università di Palermo.
- J.R. Taylor, Introduzione all’analisi degli errori, Zanichelli.
- Notes by the teacher.
Course Planning
| Subjects | Text References | |
|---|---|---|
| 1 | Metrology and error theory | - Introduzione all’analisi degli errori.- Notes by the teacher. |
| 2 | Circuits and Analog Instruments. | - Strumenti e m todi di misura,- Notes by the teacher. |
| 3 | Measurement of the main mechanical quantities. | - Strumenti e m todi di misura,- Notes by the teacher. |
| 4 | Strain measurement. | - Analisi delle sollecitazioni: Estensimetria.- Notes by the teacher. |
Learning Assessment
Learning Assessment Procedures
The exam consists of an oral test.
During the lessons, application exercises of the course contents are performed in the laboratory and in the classroom aimed at learning practical experimentation by the students. The laboratory exercises, each described in the form of a technical report, and the topics covered during the lectures are discussed during the oral exam.
During the lessons, application exercises of the course contents are performed in the laboratory and in the classroom aimed at learning practical experimentation by the students. The laboratory exercises, each described in the form of a technical report, and the topics covered during the lectures are discussed during the oral exam.
The evaluation during the oral interview will be based on: knowledge of the topics covered, the relevance of the answers to the questions asked, the ownership of technical language, the ability to make connections between the contents of the program.
To guarantee equal opportunities and in compliance with current laws, interested students can request a personal interview in order to plan any compensatory and/or dispensatory measures, based on the educational objectives and specific needs.
You can also contact the CInAP (Centre for Active and Participated Integration - Services for Disabilities and/or DSA) professor of your Department.
Examples of frequently asked questions and / or exercises
- The candidate describes how to normalize a Gauss curve.
- The Candidate explains the fundamental laws of thermocouples.
- The Candidate describes the best configurations for measuring bending with strain gauges.
- The Candidate will explain the theory of interferometry and the application in the interferometric bench.