37515 - Mechanical and Thermal Measurements

Learning outcomes

The main objectives of the course are to introduce and discussthe main issuesrelated to measurements on mechanical and thermal systems, to the acquisition, analysis, processingandinterpretation ofmeasurement results, and to the understanding and selection of sensors most widely used for physical quantities measurements.

Course contents

Basic principles

Measurement concept: definitions and standardisation. General measurement systems configurations. Examples of application to different application areas.

 

Static characteristics of measuring instruments

Static calibration and calibration curve. Statistical data analysis. Metrological characteristics: accuracy, sensitivity, treshold, resolution, hysteresis, linearity. Uncertainty: definitions and standardisation, analysis and determination.

 

Dynamic characteristics of measuring instruments

Introduction and general equation. I and II order instruments and response to typical inputs. Response to periodic and transient inputs. Experimental measurement od dynamic parameters.

 

Basics of signal analysis

Periodic, transient and random signals. Auto- e cross-correlation functions. Power spectral density. Frequency response to general inputs.

 

Analog-to-digital conversion

Quantisation and coding. Analog signal acquisition and conditiong. A/D converters. Sequential and simultaneous multi-channel acquisition configurations.

 

Dimension, displacement and velocity measurements

Callipers, potentiometres, optical proximity sensors. Incremental and absolute encoders.

 

Absolute displacement, velocity and acceleration measurements

Sismometers. Accelerometers and piezoelectric accelerometers. Accelerometer calibration.

 

Deformation measurements

Strain gages. Resistance strain gages: types, applications, manufacturing and fixing of sheet strain gages, Wheatstone bridge, temperature effect, strain measurement configurations.

 

Force, torque and power measurements

Scales and piezolelectric and strain gage load cells. Torquemeters.

 

Pressure measurements  

Manometers, piezoelectric, piezoresistive and capacitive pressure sensors.

 

Temperature measurements  

Thermometers e thermocouples. Thermoresistances e thermistors.

Readings/Bibliography

E.O. Doebelin, Strumenti e Metodi di misura , McGraw Hill

G. Rossi, Misure meccaniche e termiche: basi teoriche e principali sensori e strumenti, Carocci

R. Figliola, D. Beasley, Theory and design for Mechanical Measurements, Wiley&Sons

G. Minelli, Misure meccaniche , Patron

Teaching methods

Teaching is divided into lectures in the classroom and in the Laboratorio Meccanica e Aeronautica of the Dipartimento di Ingegneria Industriale, at the hangar. Hands-on lessons are useful to get a deeper insight of some of the topics treated in the course.

Assessment methods

The assessment of learning outcomes is done through a written examination.The latter aims at verifying knowledge acquired during the course, related to the execution of measurements under both static and dynamic conditions, and the operation and calibration of instruments analysed during the course. The written test consists of three questions of which at least one is focused on the first part of the course, i.e. static and dynamic performance of measurement systems. If the event of full pass, the obtained grade can be confirmed or an oral examination taken.

Teaching tools

Video Projector, pc

Office hours

See the website of Raffaella Di Sante