bille Janka

OBS: Mesure de la dureté des métaux. On applique, sur une surface légèrement polie du métal (...) une bille en acier spécial très dur (...) sous une charge déterminée. Il se forme alors dans la pièce une empreinte permanente, en forme de calotte sphérique [méthode de Brinell] (...)

OBS: With the change to SI units a special hardened steel tool (known as the Janka hardness tool) rounded to a diameter of 11.3 mm (projected area 100 mm2) is embedded to one-half of its diameter into the (20mm) test piece ... an electrical contact ... rings a signal bell when the correct depth of penetration has been reached ... the hardness test is performed ... on the static bending specimen.... The rate of penetration of the ball is 0.11 mm/s ... there is a very good correlation between the side hardness of timber, as determined by the Janka hardness tool, and its compression strength perpendicular to the grain.