Mechanics of Near Tip Microcracking in Brittle Material

摘要

A continuum mechanics description, of the phenomenon of stress induced microcracking has been used to study the near tip stress and strain fields and the size and shape of a small scale damaged zone for a stationary mode I crack in an elastic body. The microcrack density was found to characterize three regions of interest. In the outer region the microcrack density is zero and the stress and strain fields are purely those for linear elastic deformation. This elastic field constrains the microcracking deformation which in combination with material weakening due to microcracking causes stress relaxation in a region of intermediate microcraking. Very close to the crack tip the microcrack density is saturated and the stress field becomes again singular but with a lower stress intensity than would prevail in the absence of microcracking. In the case where very rapid microcracking occurs as the strain is increased, the intermediate microcracking zone is still present providing continuity of the strain field and a smooth transition of the stress field from the purely elastic region to the region with saturated microcrack density.