Issue 33

M.Kurek et alii, Frattura ed Integrità Strutturale, 33 (2015) 302-308; DOI: 10.3221/IGF-ESIS.33.34 307 introduce the boundary plasticization value according to the Tresca hypothesis (max. {B} = 2). Thus, the formula analogical to (3) is as follows:                  45 1 1 3 4 2 2 B  (20) When we analyse the data shown in Fig. 4, we can see that the points defined as scatter minimum for individual materials, lie along the more convex curve. Considering this, a new curve has been proposed, satisfying the same boundary conditions as the formula (20) - with the arguments fitting within range <0, 2>, in the following form:                  45 1 1 15 16 4 2 B  (21) Figure 4 : The relationship between the angle β and the parameter B 2 according to different models. C ONCLUSIONS nalysing the results of fatigue tests and calculations, it can be concluded that: 1. The multiaxial fatigue criterion proposed for life estimation is applicable to wide range of materials from resilient-brittle to resilient-plastic state. 2. The Carpinteri et al. hypothesis has proven to be right. The hypothesis concerns orientation rotation for the critical plane defined by normal stresses by the angle dependent on the ratio of fatigue boundaries for bending and torsion. 3. The Tresci criterion has been taken as the boundary condition for materials in resilient-plastic state. The new form of formula for the critical plane orientation rotation angle has been proposed on the basis of this condition. 4. Further verification is required for other materials and other loading conditions. A