Strain Measurement (Book Series: Measurement of Physical and Chemical Quantities)

• Type: Book
• Date: 2012

Authors

Maria Teresa Restivo (Author) FEUP; Fernando Gomes Almeida (Author) FEUP; Maria de Fátima Chousal (Author) FEUP

Publisher

International Frequency Sensor Association (IFSA) Publishing

Barcelona

Scientific classification

FOS: Engineering and technology

CORDIS: Technological sciences

Other information

Abstract (EN): The present work, entitled “Strain Measurement”, is the first volume in the series “Measurement of Physical and Chemical Quantities”. Two new works, on temperature and on displacement measurement, will be offered in the near future. This first edition is devoted to strain measurement considering its relevance in the engineering field. Invited authors are also contributing to specific topics with valuable perspectives. The text starts by introducing the elementary concepts of stress and strain state of a body. Next, several experimental extensometry measurement techniques are briefly introduced highlighting and covering the fundamental concepts of the mostly universal one: the electric resistance extensometry using electrical strain gauges. Basic instrumentation theory and techniques associated with the use of strain gauges are presented. Looking forward into modern advanced techniques optical fibre based extensometry is also covered. Taking into account the importance of the evaluation of measurement uncertainties the publication ends with the uncertainty estimation on the measurement of mechanical stress. The different chapters include several multimedia components such as animations, simulations and video clips. Chapter 1, Elementary concepts of stress and strain, presents fundamental concepts of the states of stress and strain. The understanding of these concepts is fundamental for the theme under study and aims at the accurate experimental evaluation based in the measurement of stress and strain states in loaded bodies (parts, structures…). A non exhaustive summary of some measurement techniques is also presented, emphasizing resistance extensometry, the most universal method. Chapter 2, Strain gauges: basic concepts, conveys the basic concepts on strain gauges, namely their working principle and the most relevant characteristics. The meaning of self-compensated strain gauges is explained. Parameters that must be taken into account for the selection of a strain gauge are also referenced and some helpful guidelines are provided. Chapter 3, Resistance extensometry: instrumentation and associated techniques, deals with a set of fundamental concepts on instrumentation, signal conditioning and various techniques that are instrumental to minimize the main causes of measurement error that are inherent to the use of strain gauges. Along the chapter the use of a few simple numerical calculations “A few numbers!” are applied in order to clarify some notions. Chapter 4: Strain measurement using optical fibres, is written by the invited authors José Luís Santos, L.A. Ferreira and F.M. Araújo. This chapter describes the use of the optical fibre as a sensing element which is being increasingly explored for measurement of physical quantities of which strain is a remarkable example. This chapter describes the working principle of optical fibre sensors and their application to strain measurement. Two sensorial structures are reviewed with detail, the Mach-Zehnder interferometer and the fibre Bragg grating, that may be considered as the optical equivalent of the electric resistance strain gauge. Chapter 5: Uncertainty estimation on the measurement of mechanical stress, is shared between Maria Teresa Restivo and invited author Carlos Sousa. Measurement is a fundamental activity in all engineering areas. But the result of a measurement action is not complete until the measured value is paired with information about its associated uncertainty. In this chapter the measurement of the flexural normal stress at the surface of a cantilever beam using resistance strain gauges is used as basis for uncertainty estimation. The authors hope to have contributed with fundamental concepts and technical information on the topic of strain measurement. This contribution has been clearly enriched with the involvement of the invited authors.

Language: English

Type (Professor's evaluation): Scientific

Notes: plus media contents

No. of pages: 106

ISBN: ISBN: 978-84-615-989

Collection: Book Series: Measurement of Physical and Chemical Quantities