Issue 41

Ch. F. Markides et alii, Frattura ed Integrità Strutturale, 41 (2017) 396-411; DOI: 10.3221/IGF-ESIS.41.51

the case for the “transtropic” material for which clearly γ rθ

( r , θ )≠γ rθ

( r , θ +Δ θ ). Moreover, it is observed that the differences

in deformation between the particular “fictitious” isotropic and “transtropic” discs are more pronounced for ϕ o =60 o .

(a)

(b)

Figure 4 : Deformed vs. undeformed (black dashed line) configuration of an element (Δ r , Δ θ ) (oriented along the loading axis and normally to it), for an isotropic (green line) and a “transtropic” (red line) disc, when the loading direction is ϕ o =20 o (a) and ϕ o =60 o (b) . The role of the length of the contact arc, 2ω o The specific parameter, i.e., the length of the loaded arc, is in general disregarded in practical applications of the Brazilian disc test, since it is considered that the stress state at the disc center can be simulated as a biaxial stress field with a con-

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