Fracture Mechanics 2

Question 1

Why is it important to have plane strain when measuring the fracture toughness of the material?

Answer 1

Because plane strain can lead to brittle failure

Question 2

What are the conditions for a valid measurement of fracture toughness?

Answer 2

Crack must be sharp
•Crack length must be large compared with the plastic zone size
•Crack tip material must be in plane strain condition

Question 3

What failure is preferred, Brittle or Ductile?

Answer 3

Brittle failure (fast fracture) is an undesirable failure mode, Ductile failure involving yield is more desirable. It is therefore desirable to ensure that ductile failure is the most probable mode. It is also desirable that the material be able to withstand large defects prior to failure