This set of Materials Science Multiple Choice Questions & Answers (MCQs) focuses on “Fracture Mechanics”.
1. Which of the following part of mechanics deals with study of crack propagation?
a) Solid mechanics
b) Fluid mechanics
c) Applied mechanics
d) Fracture mechanics
Explanation: Fracture mechanics is that part of mechanics which deals with the study of propagation of cracks. Solid mechanics and fluid mechanics deal with solid body and fluid respectively.
2. Which of the following is not a mode of application of force for crack propagation?
a) Opening mode
b) Sliding mode
c) Tearing mode
d) Rolling mode
Explanation: The application of force for the crack to propagate can be mainly of three types which are opening mode, tearing mode, sliding mode. Rolling mode cannot be used.
3. Fractography is the study of surfaces of materials which are fractured
Explanation: The above statement is true and fractography is indeed the study of surfaces of materials which are fractured. They are used mainly in forensic engineering or during failure analysis.
4. What amount of actual stress would be needed to fracture bulk glass?
a) 10 MPa
b) 20 MPa
c) 100 MPa
d) 50 MPa
Explanation: To fracture bulk glass, a force of about 100 Mpa or 15000 psi would be needed.
5. What amount of actual stress would be needed to fracture bulk glass?
a) 1000 MPa
b) 2000 MPa
c) 10000 MPa
d) 5000 MPa
Explanation: To fracture bulk glass, theoretically the stress needed to break the atomic bonds of the glass would be 10000 Mpa or 1500000 psi.
6. According to Griffith if f is stress at fracture and a is flaw length then which of the following is true?
Explanation: Griffith on conducting his experiment found out that the multiplication of stress at fracture and the square root of the flaw length remains constant.
7. Which of the following scientist proposed a modification to Griffith’s theory?
a) G. R. Irwin
b) Albert Einstein
c) Isaac Newton
d) There was no modification proposed.
Explanation: G. R. Irwin and people working under him at the U.S. Naval Research Laboratory found out that plasticity also plays a role in fracture of material and hence they proposed a modification.
8. What is the unit of G from Griffith’s energy criterion?
Explanation: G is the surface energy and is the given by energy per unit area which can be found out by dividing J by m2 to get the final answer as J/m2.
9. For polymers close to glass transition temperature which of the following can be a value of G?
a) 1 J/m2
b) 900 J/m2
c) 1200 J/m2
d) 1400 J/m2
Explanation: 900 J/m2 can be value of G for polymers close to glass transition temperature as the range of the G for this case is known to be 2 J/m2 to 1000 J/m2. As the other options lie out of this range, there is only one correct answer.
10. Fracture stress decreases as fiber diameter decreases.
Explanation: The above statement is false as the fracture strength is known to increase when the fiber diameter decreases as observed by Griffith.
Sanfoundry Global Education & Learning Series – Materials Science.
To practice all areas of Materials Science, here is complete set of 1000+ Multiple Choice Questions and Answers.