This set of Composite Materials Multiple Choice Questions & Answers (MCQs) focuses on “Stress-Strain Relations for a Anisotropic Materials – String – Set 2”.
1. What does the terms S11, S22 and S33 in the compliance matrix represent?
a) Extensional bending to an individual applied stress
b) Extensional stiffness to an individual applied stress
c) Normal stresses to an individual applied stress
d) Normal strains to an individual applied stress
View Answer
Explanation: All the terms in the compliance matrix represents the couplings for an arbitrarily stressed body. Out of which, S11, S22 and S33 represents the extensional response to an individual applied stresses σ1 , σ2 and σ3 respectively.
2. The terms representing the coupling between the dissimilar normal stresses and normal strains are __________
a) s11, s22 and s33
b) s12, s22 and s33
c) s12, s13 and s23
d) s11, s23 and s33
View Answer
Explanation: The extension–extension coupling is more commonly known as the Poisson’s effect that relates the normal shear stress to the normal shear strain as a relation of Τxy and γ12. They are linked in the compliance matrix as the co-efficient S12, S13 and S23.
3. The terms s44, s55 and s66 in the compliance matrix represents __________
a) shear modulus
b) extension modulus
c) coupling
d) bending stiffness
View Answer
Explanation: The terms s44, s55 and s66 in the compliance matrix represents the shear and they will be related to the shear moduli in the 2-3,3-1 and 1-2 planes respectively.
4. The elasticity tensor Cmnrs in the transformed system is given as __________ (where T = Transformation matrix)
a) Cmnrs = Ti Tk Ti Tl Cijkl
b) Cmnrs = Ti Tj Tk Tl Cijkl
c) Cmnrs = Tj Ti Tl Tk Cijkl
d) Cmnrs = Tj Ti Tk Tl Cijkl
View Answer
Explanation: While transforming from the original coordinate system to any other transformed coordinate system, the sequence of the transformation has to be followed in order to have the same representation in the transformed system. That transformation is given by the transformation matrix (T) i.e., Cmnrs = Ti Tj Tk Tl Cijkl.
5. Which of the following is not an anisotropic material?
a) Diamond
b) Composite material
c) Bone
d) Glass
View Answer
Explanation: Anisotropic material properties are different in different directions. Common anisotropic materials include wood, because its properties are different in parallel and perpendicular to the grain, and layered rocks such as slate. Similar explanation can be given to diamond and composite materials including bone as well when it comes to anisotropic properties. Glass is an isotropic material.
6. What is the S11 term of the compliance matrix of a glass/epoxy lamina whose material property E1= 181GPa?
a) 9.709 * 10-9 Pa-1
b) 5.525* 10-9 Pa-1
c) 5.525* 10-12 Pa-1
d) 9* 10-9 Pa-1
View Answer
Explanation: Given E1 = 181GPa
We know that,
S11 = 1/ E1
= 1/ (181 * 109)
= 5.525* 10-12 Pa-1.
7. What is the value of S44 in the compliance matrix of a glass/epoxy lamina whose G23 = 3GPa?
a) 3.33* 10-9 Pa-1
b) 3.33* 10-10 Pa-1
c) 3.33* 10-12 Pa-1
d) 3.33* 10-15 Pa-1
View Answer
Explanation: Given G23 = 3GPa
We know that,
S44 = 1/ G23
= 1/ (3 * 109)
= 3.33* 10-10 Pa-1.
8. Which of the following coupling term is not linked in the compliance matrix?
a) Extension – extension coupling
b) Shear – extension coupling
c) Shear – shear coupling
d) Bending coupling
View Answer
Explanation: The terms S11, S22, S33 represents extension in the same direction. S12, S13, S23 represents extension – extension coupling and the terms S14, S15, S16, S24, S25, S26, S34, S35, S36 represents the shear – extension coupling while the terms S44, S55, S66 signifies shear and S45, S46, S56 represents the shear – shear coupling.
9. The relationship between the terms C1212, C1111 and C1122 is given by ___________
a) C1212 = C1111 + C1122
b) C1212 = C1111 – C1122
c) C1212 = ½ (C1111 + C1122)
d) C1212 = ½ (C1111 – C1122)
View Answer
Explanation: The isotropy of a material results in the following additional relationship among the materials. C1212 = ½ (C1111 – C1122).
Sanfoundry Global Education & Learning Series – Composite Materials.
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