Consider a cubic block whose sides are 6 cm long and a cylindrical block whose height and diameter are also 6 cm. both blocks ar
e initially at 22°c and are made of granite (k = 2.5 w/m · °c and a = 1.15x 10-6 m^2/s). now both blocks are exposed to hot gases at 550°c in a furnace on all of their surfaces with a heat transfer coefficient of 45 w/m2 · °c. determine the center temperature of each geometry after 10, 20, and 60 minutes.
1 answer:
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Answer:
0.39 nM
Explanation:
The critical crack tip radius from the equation
attached below
for fracture to occur the бm will have to reach the fracture strength of material
i.e. бm = E/10
from equation 2 attached below
St = ( 400 * a * бo^2 ) / E^2 ------ 3
Given <em>: a = 2*10^-3 mm , бo = 275 MPa, E = 393 * 10^3 MPa ( gotten from table)</em>
Input given values into equation 3
St = 3.9 * 10^-7 ≈ 0.39 nM
