Solids Rheometers and the Measurement of Fundamental Elastic Properties

Solids Rheometers and the Measurement of Fundamental Elastic Properties 

Solids rheometers are instruments in which solid samples of regular shape are subjected to well-defined deformations, and the forces required to do this are measured. 

The sample, usually in the form of a cylinder, can be subjected to uniaxial compression (the simplest and most common test), uniaxial tension, shear, bending or torsion. In compression, the sample rests on the base-plate and is compressed by a horizontal flat plate attached to the crosshead when 

Paradoxically, diametric compression, in which a disc-shaped sample is compressed diametrically between the crosshead plate and the base-plate, can be used to measure tensile strength (Gunasekaran and Ak, 2002). It is a simpler option than tensile testing because of the difficulty in the latter of satisfactorily gripping food material samples, which are relatively weak. 

A double compression test, in which the same sample is subjected to two consecutive compressions and unloadings , forms the basis of the Texture Profile Analysis (TPA) technique, which yields mainly empirical 

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