Experimental Methods in Mechanical Engineering
Objectives
It is intended that the student''s contact with various experimental techniques allows them to know or predict the responses exhibited by structures subjected to static or dynamic loads. In the presence of these responses, the student is asked to compare them with those obtained through theoretical models. Explaining the differences between the results obtained by both methods is one of the important tasks that the student should be able to perform.
As the various experimental works are carried out in groups, it is essential for the student to promote their development and critical work in this environment, as well as to manage their time correctly. It is also intended, with the preparation and discussion of the reports, that the student develops his/her skills in technical writing and oral presentation.
General characterization
Code
8451
Credits
6.0
Responsible teacher
Pedro Samuel Gonçalves Coelho, Raquel Albuquerque Soares Brás de Almeida
Hours
Weekly - 4
Total - 59
Teaching language
Português
Prerequisites
As an integrative discipline, it is necessary that students already have a consolidated background in Statics and Dynamics of rigid bodies, Mechanics of Solids, and very importantly in Mechanical Vibrations.
Bibliography
Encyclopedie VISHAY d''''Analyse des Contraintes" Ed da VISHAY Micromesures.
"Fundamentos de Extensometria Eléctrica" - A.P. Vale Urgueira FCT- 2003
"The Strain Gage Primer", CC Perry, HR Lissner, McGraw Hill
"Dinâmica - Mecânica Vectorial para Engenheiros", Beer and Johnston Mc Graw Hill 1998
RS Figliola, DE Beasley; "Theory and Design for Mechanical Measurements", John Wiley Sons
KG McConnell "Vibration Testing - Theory and Practice", John Wiley Sons
Maia et all, "Theoretical and Experimental Modal Analysis", RSP
JH Ginsberg "Mechanical and Structural Vibrations - Theory and Applications", JWS
Teaching method
The curricular unit consists of several modules taught in theoretical classes, some dealing with new material in the course and others making an interconnection of various subjects, however learned throughout the course. Essentially, the first module deals with the response measurement techniques using electrical strain gauges, the second considers the effect of the uncertainties of the equipment and the measurement chain on the final value that is intended to be obtained experimentally and in the third Practical models associated with various matters of rigid body dynamics and mechanical vibrations are developed. Students have to carry out several laboratory works, in groups, to present the respective reports, thus having the opportunity to develop the critical spirit of analysis of the results as well as teamwork.
Evaluation method
The evaluation implies the completion of all laboratory work (TL) and reports on four of them, previously defined. These reports are subsequently discussed with each group of students, and the result of all work must be positive. All laboratory work has equal weight in the final average of each student, that is, the final grade is determined by the following weighted average,
Final grade = 0,25*TL1+0,25*TL2+0,25*TL3+0.25*TL4 ≥ 9,5 Values
There is NO possibility of taking an exam (at any time) since the UC assessment is based on reports and discussion of the laboratory work carried out.
Subject matter
Experimental stress analysis: Basic principles of electrical extensometry and photoelasticity. Placement of strain gauges. Wheatstone Bridge. Rosette of extensions. of Stress concentration.
Dynamics: Determination of the moments of inertia of rigid bodies from the use of the composite and bifilar pendulum.
Mechanical Vibrations: Introduction to experimental modal analysis of vibratory systems.
Data Acquisition Systems: Fundamentals of signal theory. Signal processing and conditioning. Transducers: force measurement; pressure; displacement; speed; acceleration; flow.