On the Nature of the Shore Hardness

The author intends to explain the relation between the Shore hardness and the indentation hardness and then to clarify the nature of the former. In measuring the Shore hardness for a given material, a light hammer provided with a small ball is used. Let us denote the resisting force of material at an instant in the compressing period by P and the corresponding depth of indentation by x, then we may write P=ax+bxn. By using this relation, he obtained the relation HS=HB/HE where HB=Brinell hardness number. HE should be called elastic hardness. This expression means that the Shore hardness is proportional to the Brinell hardness for all the materials having equal elastic properties, for example for the ordinary carbon steel from mild to hard steel.