EXPECTED PRINCIPAL STRESS DIRECTIONS UNDER MULTIAXIAL RANDOM LOADING - PART I - THEORETICAL ASPECTS OF THE WEIGHT FUNCTION-METHOD

As has been observed experimentally by many authors, the position of t he fatigue fracture plane appears to strongly depend on the directions of the principal stresses or strains. In Part I of the present work t he expected principal stress directions under multiaxial random loadin g are theoretically obtained by averaging the instantaneous values of the three Euler angles through some suitable weight functions which ar e assumed to take into account the main factors-influencing fatigue be haviour. Then, in Part II, it is examined how such theoretical princip al directions determined by applying the proposed procedure are correl ated to the position of the experimental fracture plane for some fatig ue tests reported in the literature. (C) 1998 Elsevier Science Ltd. Al l rights reserved.