Calculate maximum allowable stress

[cd19]

1. A decision has been made to make a plate out of an advanced engineering material ceramic that has better high temperature and wear properties than alloys. The plate must withstand a tensile load of 177.92kN. The part will be non-destructively tested to ensure that no flaws are present that might cause failure. A company offers non-destructive testing methods using x-ray radiology that can detect flaws larger than 0.05 cm. Assume Y=1.0. Determine the minimum thickness for a 7.5mm wide plate made of sialon (Kic = 9.9 Mpa\sqrt{}m) . Also calculate the maximum allowable design stress.



2. Kic = Y*\sigma*sqrt{\pi*a}

\sigma _allowable = FORCE/AREA



3. I just don't see how to factor in the 'thickness' into my calculations and so i cannot begin with my calculations. Can someone help me with this please.

 

[edgepflow]

Stress in a plate is a different than the direct tension formula you listed.

Have a look at:

http://www.efunda.com/formulae/solid_mechanics/plates/casestudy_list.cfm