Young's Modulus of a Composite

It can be calculated as 57% of the force applied parallel to the fibre axis is carried by the glass fibre. In summary, when Nylon contains 30% by volume glass fibres, 57% of the force applied parallel to the fibre axis is carried by the glass fibre due to the strong bonding between the two materials.
  • #1
LeftBrain
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Homework Statement


Glass fibres in Nylon provide reinforcement. Young's modulus of glass fibre is 72.4GPa; Young's modulus of Nylon is 2.8GPa.
If the Nylon contains 30% by volume glass fibres, what fraction of the force applied parallel to the fibre axis is carried by the glass fibre?

(Assume the bonding between glass fibre and Nylon is strong enough to transfer the load, so εc = εf = εm applies)

Homework Equations



Ecl = (ff ⋅ Ef) + (fm ⋅ Em)

Where
Ecl = Young's modulus of composite in parallel direction
ff = Fraction of the fibre
Ef = Young's modulus of the fibre
fm = Fraction of the matrix
Em = Young's modulus of the matrix

The Attempt at a Solution



Given that Nylon is the matrix and the glass fibres are the fibre, the following can be assumed...

Ecl = (0.3 ⋅ 72.4) + (0.7 ⋅ 2.8) = 41.32 MPa

With respect to the fraction of the force applied parallel to the fibre axis, is it a matter of dividing the Young's modulus of the composite by that of the fibre?

41.32 MPa / 72.4 MPa = 0.57 or 57%
 
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  • #2
Yes.
 

1. What is Young's Modulus of a Composite?

Young's Modulus of a Composite is a measure of the stiffness or rigidity of a composite material. It is also known as the elastic modulus and is represented by the symbol E. It describes how much a material deforms under a given amount of stress.

2. How is Young's Modulus of a Composite calculated?

To calculate Young's Modulus of a Composite, the stress-strain curve of the material is plotted. The slope of the curve in the linear elastic region represents the Young's Modulus. It is calculated by dividing the stress (force per unit area) by the strain (change in length per unit length).

3. What factors can affect Young's Modulus of a Composite?

The Young's Modulus of a Composite can be affected by various factors such as the type and amount of reinforcing fibers, the orientation of the fibers, the matrix material, and the manufacturing process used. Other factors include temperature, humidity, and loading conditions.

4. How is Young's Modulus of a Composite used in engineering applications?

Young's Modulus of a Composite is an important property in engineering applications as it helps engineers to design and select materials for specific purposes. It is used to predict how a material will behave under different conditions and to determine the maximum stress a material can withstand before it starts to deform.

5. Can Young's Modulus of a Composite change over time?

Yes, Young's Modulus of a Composite can change over time due to various factors such as fatigue, creep, and environmental degradation. These changes can affect the mechanical properties of the material and can lead to failures if not accounted for in the design and usage of the material.

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