Question

Fracture Mechanics: A specimen of a 4340 steel alloy having a plane strain fracture toughness of 45 MPa m ( ) is exposed to a stress of 1000 MPa (145,000 psi). Assume that the parameter Y has a value of 1.0. a) Calculate the critical stress for brittle fracture of this specimen if it is known that the largest surface crack is 0.75 mm (0.03 in.) long. b) Will this specimen experience fracture

Answer 1

Answer:

a)  927 MPa

b)The specimen will experience fracture

Explanation:

a) Calculate critical stress for brittle fracture

σ = fracture toughness / (y √ π * surface crack)

  = 45  /  ( 1  $\sqrt{\pi * ( 0.75*10^-3)}$  )

  = 927 MPa

b) since critical stress( 927 MPa)  < 1000 MPa

hence : The fracture will occur