Question

A structural component in the shape of a flat plate 25.0 mm thick is to be fabricated from a metal alloy for which the yield strength and plane strain fracture toughness values are 545 MPa and 29.6 MPa-m1/2, respectively. For this particular geometry, the value of Y is 1.3. Assuming a design stress of 0.3 times the yield strength, calculate the critical length of a surface flaw. (in mm)

incorrect answer 2.222 mm

Answer 1

Step 1

Given that:

Flat plate size = 25.0 mm

Yield strength() = 545 MPa

Plane strain fracture toughness(KIC) = 29.6 MPa-m1/2

Dimensionless parameter(Y) = 1.3

Design stress = 0.3 * => 0.3 * 545 MPa

Design stress = 163.5 MPa

Step 2

A particular geometry, need to determine the critical flaw size for material,

We have equation for plain structure fracture toughness,

KIC = Y

ac is the maximum allowable flaw size,

The maximum allowable flaw size(ac)

On calculating the above equation we get,