

H. L. Ewalds and R. J. H. Wanhill, Fracture Mechanics, Edward Arnold and Delftse Uitgevers Maatschappij, 1984 THE THREE MODES OF LOADING All stress systems in the vicinity of a crack tip may be derived from three modes of loading, figure 2.1 [right]. In what follows the derivation of elastic stress field equations will be limited to mode I, since this is the predominant stress situation in many practical cases. Once this derivation is understood it is possible to obtain a number of useful expressions for stresses and displacements in the crack tip region. However, use of the stress intensity factor approach for practical geometries does involve some difficulties.
