Processes taking place in the contact of two bodies and having an
influence on strength and service life of machinery or of the whole
structure have been in the interest of physicists and engineers for a
very long time. The first scientific base had been created by H. Hertz
(see Hertz. H.: tJber die Berührung. fester elastischer Körper. J. reine
und angewandte Mathematik. 1882. 92. pp. 156-171 ) more than one hundred
years ago. Since that time (proportionally to the need of industry)
countless numbers of other studies have originated, But practice always
has been an inspiration for the solution being more general and
profound. At the beginning only the problem of the contact of two solid
elastic bodies was solved. It was followed with the problems of local
load by forces on an elastic half-plane and half-space (see Boussinesq.
J.: Application des potentials. d l 'etude de l 'equiZibre et du
mouvement des solides elastiques. Paris 1885). The integration then has
enlarged the point contact into a surface one so as to correspond to
geometry, rigidi ty or physical properties of material in the place of
contact. At present days even the effect of different frictions, origin
and propagation of cracks are being solved. Not only mathematics and
computers but even modern experimental methods are involved in the
solution of problems.