Kr. Shah et Tf. Wong, FRACTURING AT CONTACT SURFACES SUBJECTED TO NORMAL AND TANGENTIAL LOADS, International journal of rock mechanics and mining sciences, 34(5), 1997, pp. 727-739
Citations number
51
Categorie Soggetti
Geochemitry & Geophysics","Mining & Mineral Processing
A variety of rock engineering problems including drilling, cutting, ab
rasion, and milling involve rock tool contact and indentation. The pat
tern of indentation fractures and the role of slip conditions, surface
roughness, tool radius and initial flaw size for an arbitrarily loade
d contact are not fully known, The present paper aims to identify the
elastic stress field for a contact subjected to both normal and tangen
tial loads, and evaluate the condition for the fracture initiation and
propagation. Stress fields within two spheres at contact are availabl
e when either only normal load is applied or when tangential load caus
es full-slip conditions, It is shown here that through appropriate sup
erposition of the above two solutions, the stress field under partial-
slip conditions, as well as during the unloading of tangential force m
ay be determined. Maximum tensile stress increases significantly under
partial-slip conditions as compared to the full-slip case even though
the same magnitude of tangential force is applied, The location of ma
ximum tensile stress moves inward from the trailing edge as the tangen
tial force is unloaded, The stress-intensity factors for a penny-shape
d crack which initiates at the contact periphery, and follows the mini
mum principal stress trajectory are obtained and utilized to study ind
entation fracturing, The dependency of critical loads on initial flaw
size, indenter radius and slip conditions is quantified, The predictio
ns of fracture density and spacing under a sliding indenter are achiev
ed through a simple estimate of shielding interaction between adjacent
fractures. Relation of these evenly spaced fractures with the formati
on of wear grooves on sliding surfaces is discussed. (C) 1997 Elsevier
Science Ltd.