A novel volume–pressure hardness (HVP) on the transverse section of wood as a modification of the Brinell measure

Abstract The Brinell ball hardness test is based on either the total surface area of the indentation or the depth of the indentation. Although the Brinell hardness test is well-established, none of its basic definitions have a clear physical justification. Consequently, the Brinell hardness measure in the experiment depends on the load value, with a maximum for half-diameter indentations and a minimum for full indentations. Therefore, a slightly different hardness measure for the ball test has been proposed, which is based on the volume of the indentation and, at the same time, has an energetic justification. The new hardness measure is abbreviated as HVP, derived from the words hardness–volume–pressure, which best reflects the essence of this measure. Two equivalent definitions of the HVP measure have been given. The first geometric definition relates the volume of a real indentation to the indentation volume of an ideal parabolic indenter. The second energetic definition is based on the average volume work of deformation of the material resisting hardness, in terms of pressure (stress). Preliminary experimental results showed no significant correlation between the HVP hardness measure and the applied load. However, the Brinell hardness measure showed a negative correlation with load in two of three sets of transverse section measurements of linden wood. These results reached a statistical significance level of 0.05.