Quiz: Section 1.1 Introduction – Mechanics of Composite Materials OCW

A composite is structural material? What is it defined as? (Choose most appropriate answer)
(A) consisting of two or more constituents.
(B) metal
(C) polymers
(D) ceramics

Advanced composites are
(A) naturally found.
(B) traditionally used in aerospace
industries.

Composites are easy to repair.
(A) False
(B) True

What fiber factors contribute to the mechanical performance of a composite?
(A) Orientation.
(B) Length, Shape and Orientation
(C) Shape.
(D) Length.

The most common advanced composites are
(A) Ceramic Matrix Composites.
(B) Polymer Matrix Composites.
(C) Metal Matrix Composites.

One of the major drawbacks of composites is
(A) 10 percent.
(B) -15 percent.
(C) 15 percent.
(D) 5 percent.

Reducing one pound of mass in a commercial aircraft can save up to how many gallons per year?
(A) 350.
(B) 3500.
(C) 50.
(D) 30000.

A steel wire will generally have __________ order of strength than the bulk steel it is made from.
(A) Much higher
(B) Same
(C) Much lower

A steel wire will generally have __________ order of Young’s modulus than the bulk steel it is made from.
(A) Much lower
(B) Much higher
(C) Same.

What is the most common cross-sectional shape of fibers?
(A) Square
(B) Triangular
(C) Circular
(D) Rectangular

Where are advanced composites primarily used?
(A) marine industry
(B) furniture industry
(C) construction industry
(D) aerospace industry

What is the definition of specific modulus?
(A) Young’s modulus/density
(B) Young’s modulus/specific gravity
(C) density/Young’s modulus
(D) Young’s modulus/specific heat

Fibers are of thin diameter because they have ______________ than the bulk material
(A) higher flexibility
(B) lower toughness
(C) lower strength
(D) lower stiffness

The lightest mass of the beam required to take a compressive load and avoid buckling depends on the ratio E^a/ρ (E=Young’s modulus, ρ=density). What is the value of a?
(A) 1/2
(B) 2
(C) 1/3
(D) 1

The lightest mass of the beam required to take a tensile load depends on the ratio E^a/ρ (E=Young’s modulus, ρ=density). What is the value of a?
(A) 1
(B) 1/3
(C) 1/2
(D) 2

The lightest mass required to have minimum deflection in a beam with a bending load depends on the ratio E^a/ρ (E=Young’s modulus, ρ=density). What is the value of a?
(A) 2
(B) 1/2
(C) 1/3
(D) 1

What is the largest ingredient in glass fibers?
(A) aluminum oxide
(B) silicon oxide
(C) calcium oxide
(D) boron oxide

Other than Young’s modulus, what does the flexibility of a circular rod depend on?
(A) diameter
(B) shear modulus
(C) length
(D) Poisson’s ratio

Specific modulus is given by
(A) density/strength
(B) density/Young’s modulus
(C) Young’s modulus/density
(D) strength/density

To measure normal strain experimentally by a strain gage at a point in the body, I need to know __________ of the body
(A) nothing else
(B) shear strength
(C) Young’s modulus
(D) Poisson’s ratio

What is the unit of fracture toughness in the SI system?
(A) √MPa – m
(B) MPa- √m
(C) MPa- m
(D) √MPa – √m

Primary material selection parameters for metals are strength, affordability, corrosion resistance, and formability. What are the other two?
(A) joinability and surface smoothness
(B) joinability and toughness
(C) toughness and scratch resistance
(D) toughness and hardness

The area of the fiber-matrix interface for a fixed volume of fibers in a composite is inversely proportional to the d^p, where d is the diameter of the fiber. What is the value of ^p?
(A) 3
(B) 1
(C) 4
(D) 2

In biblical times, which material was used to reinforce the bricks?
(A) bamboo
(B) glass
(C) leaves
(D) straw

Which is NOT a significant fiber factor that contributes to the mechanical performance of a composite?
(A) mass
(B) orientation
(C) length
(D) material