Engineering Questions with Answers - Multiple Choice Questions

Materials Science MCQ’s – Fracture Mechanics

1 - Question

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
View Answer Answer: d
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 - Question

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
View Answer Answer: d
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 - Question

Fractography is the study of surfaces of materials which are fractured
a) True
b) False
View Answer Answer: a
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 - Question

What amount of actual stress would be needed to fracture bulk glass?
a) 10 MPa
b) 20 MPa
c) 100 MPa
d) 50 MPa
View Answer Answer: c
Explanation: To fracture bulk glass, a force of about 100 Mpa or 15000 psi would be needed.



5 - Question

What amount of actual stress would be needed to fracture bulk glass?
a) 1000 MPa
b) 2000 MPa
c) 10000 MPa
d) 5000 MPa
View Answer Answer: c
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 - Question

According to Griffith if f is stress at fracture and a is flaw length then which of the following is true?
a) f*a1/2
b) f*a
c) f/a
d) f/a1/2
View Answer Answer: a
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 - Question

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.
View Answer Answer: a
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 - Question

What is the unit of G from Griffith’s energy criterion?
a) J-m2
b) J-m
c) J/m2
d) J/m
View Answer Answer: c
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 - Question

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
View Answer Answer: b
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 - Question

Fracture stress decreases as fiber diameter decreases.
a) True
b) False
View Answer Answer: b
Explanation: The above statement is false as the fracture strength is known to increase when the fiber diameter decreases as observed by Griffith.

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