MECHANICAL AND THERMAL MEASUREMENTS

Academic Year 2021/2022 - 1° Year
Teaching Staff: Fabio Raffaele Emilio LO SAVIO
Credit Value: 6
Scientific field: ING-IND/12 - Mechanical and thermal measurements
Taught classes: 25 hours
Exercise: 37 hours
Term / Semester:

Learning Objectives

The course aims to provide basic measurement knowledge and an accurate transducers analysis. It deals with both static and dynamic analysis of the performance of the measurement chains. The main types of transducers are analyzed in detail with the discussion of the metrological parameters. The student engineer will be instructed on the most significant aspects of measuring devices and methods for 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

Lectures (45 hours) and laboratory or classroom exercises (15 hours).

The initial phase of the course provides an introduction to metrology and analysis of measurement errors. The main electronic terminal instruments to be used in mechanical and thermal measurements are then analyzed. The last part of the course deals with the measurements of the main mechanical quantities. During the course classroom exercises and laboratory tests will be carried out.


Detailed Course Content

Rationale for measurement operations. Concepts of magnitude and measure. Units of measurement systems: CGS, MKS, Technical System, English System, International System. Dimensional equations. Measurement schemes: direct, indirect, zeroing and deviation instruments. Theory of measurement systems: aim of the measurement; functional analysis of an instrument; active and passive transducers; flow of information in the measurement chain; errors due to disturbing factors. Statistical analysis for the "a posteriori" evaluation of uncertainties: representation of errors; best value, standard deviation and standard deviation of the mean; Gauss 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 performance of instruments: 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 flow; vibration and acceleration; mass and strength; temperature; mechanical power; pressure. Stress-strain analysis: local methods (strain gauge measurements).


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.