Connecting you to the composites industry


how to calculate the theoretical fiber volume fraction

Sign in or register to ask a question.

  • 1

how to calculate the theoretical fiber volume fraction in the composite lamina.

how to find the maximum fiber volume fraction that can be arranged in this fashion? (a problem from pk mallic book)

  • Asked by jabez
  • 19:27 on 25th September 2019


  • 1

The stiffness and strength of a composite laminate can be maximised by increasing the volume fraction of fibres in that laminate. The maximum volume fraction of fibres is a theoretical value, as it assumes that the fibres are touching, and takes no account of voids that will be present in the cured laminate.

Volume fraction of fibres in a composite laminate is derived from the fibre-to-resin weight ratio. The calculation relies on data, such as the areal weight and density (⍴) of the fibres, and the density of the resin, that should be provided by the material suppliers.

Determine the weight of fibres (Wf) by dividing the areal weight of the fibres by the area of the ply (layer of fibre).

Weigh the cured laminate.

Subtract the weight of the fibres from the weight of the laminate to determine the weight of the resin (Wr) in the laminate.

Divide the weight of fibres by the fibre density to calculate the volume of fibres, Vf:

Vf = Wf/Wr

The fibre-to-resin volume ratio, Vf/Vr = (Wf/Wr) x ( ⍴r/⍴f)

And the resin volume, Vr = 1/(1+(Vf/Vr))

We can now calculate the theoretical volume of fibres, Vf = 1 – Vr

To account for the volume of voids (Vv) in the laminate, we include another term:

Vf = 1 – Vr – Vv.


  • 0

You can calculate the volume-weight fraction using this calculator:

Volume-Weight Fraction Calculator

James Taylor

Your Answer

Sign in or create an account to help jabez and our community by answering this question.

Comments (0)

Sign in or create an account to join in the discussion.

Leave your comment

Upcoming Events




Follow us
Subscribe to our email newsletter

Subscribe to receive our weekly round-up of all the industry's latest news, jobs, events and more!

We'll always keep your personal details secure and will never share them with third parties for marketing purposes. You can unsubscribe at any time. For further details on how we may use your data, please visit our Privacy Policy.