Estimate the theoretical fracture strength of a brittle material if it is known that fracture occurs by the propagation of an elliptically shaped surface crack of length 0.5 mm (0.02 in.) and a tip radius of curvature of 5 × 10–3 mm (2 × 10–4 when a stress of 1035 mpa (150,000 psi) is applied.

20700Mpa

Explanation:

We need to find the strenght at the point where can reach a fracture, that is through the equation,

Where

= Normal stress

a= Either lenght of the internal crack or lenght of surface crack

Substituting the values:

That is the fracture strenght of brittle material at crack tip

atomic = no of protons.

mass number-atomic number = neutron number

the answer is kevlar