TABLE OF CONTENTS The very first parameter governing the constitutive law of a material is its stiffness connected with its elasticity. If elasticity laws have been known for quite a long time, the measurement of elastic characteristics itself covers many different realities, from the perfect crystal to polymer, as well as from the isotropic solid to composites, or even coatings.
This chapter is not intended as an exhaustive list of methods for measuring elastic constants, but as a panorama of the various techniques used, from standard mechanical tests to more specific tests; comparing the different methods is not an object in itself, but elements are given regarding the implementation of tests and the specimen geometry, the precision and the temperature limitations of the type of measurement, the choice in relation to the type of material (stiffness range or brittleness); all these elements will make it possible to appreciate the complementarities of various techniques and to indicate their possibilities for the user.
The presentation will be limited to "mechanical" methods in the sense that they use the application of a load and the indirect or direct reading of a deformation; X-ray diffraction methods and neutron or magnetic diffraction methods will not be dealt with here (see [HAU 97]). In order to discriminate between these methods, standard mechanical tests are distinguished as quasi-static, ultrasound and resonance methods as dynamic, and more recently, with the development of coatings, the instrumented indentation methods as local and surface methods.
[1]
[1]Chapter written by Pascal GADAUD.
