Brittle rupture

The stress conditions brittle rupture can be described by Griffith forms, i.e. 

Obviously, the small fractural angle of brittle rupture does not comply with the Coulomb shear fracture angle, i.e. yS = 45° - cpll. This shows that the rock burst has the tensile shear and pure tensile fracture mechanism. 

Figure 2.8 shows the fragments of a 5000 psi monobloc Vessel purposely tested to destruction. The fragmentation lb typical of brittle rupture. Brittle rupture may result from the use of brittle materials, notch brittleness, ... 

The above relationship indicates that in t he cousideralion of failure by brittle rupture, discus-sed previously, the aliowalde stress should l>e bast d upon the yield point rather than upon the ultimate strength of the material. Equation 2.37 does n >t take into account tlw phenomenon of stress relaxation at elevate temperature and was developed for uniaxial stres.ses (45), Such condderaUons and the applit lion of Eq. 2.37 are discussrsl in a later section of the text. 

A number of articles have appearetl reporting studies on the pr >blem of brittle rupture as a result of repeated cyclic loading (50, 52, 71-76). 

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