Principle : The thermomechanical analysis (TMA) allows you to measure quickly and easily the change of dimension of the sample (expansion, shrinkage, movement, etc.) as a function of temperature, time and applied force. the probes and the media sample are generally quartz. the geometry of these parts requires a mode of measurement. the possible modes are the following :
- expansion (probe used no force on the sample) for the determination of coefficient of expansion in dilatométrie ;
- penetration ; a strong constraint, created by a strong force applied by a probe of small diameter, increases the contribution of the penetration relative to the expansion ;
- traction (sample attached by two small clamps) to the study of films or fibers under traction.
- three-point bending (assembly consisting of support in the form of a knife) ;
- volume expansion (mounting consisting of a crucible and a tube with a flat bottom) for the study of the dilation of powders, for example.
For the modes in both penetration and bending, a stress that is more important is imposed to the sample.