The hardness of a material is defined by Martens as “resistance that is directed towards the indentation by another harder material”. In the current standardised, common hardness test methods, a hard indenter is pressed perpendicular to the specimen’s surface.
Due to the influence of the indenter geometry (sphere, cone, pyramid), the material of the indenter (steel, tungsten carbide, diamond), the size and speed of the load application and the type of measurement (under load or load release), the characteristic hardness values, with few exceptions, can be converted only partly into each other.
As hardness method for thermoplastic materials, the following are especially of interest:
For elastomers and thermoplastic elastomers, the following methods for measuring hardness were developed:
Special methods for measuring hardness with extended information are: