Im making a composite plate of 3m^2 using e-glass fiber of 600GSM and polyester resin , with 7 plies. Does it mean that each ply will have the same mass of fiber regardless of the Volume fraction?
The fiber volume (and mass) always remains constant for a given layup. Vf is the percentage or fraction of fiber within the total volume. The variable (if the layup is consistent) is the volume of resin within the sample. As the Vf goes up the resin volume must go down.
Scenario #1:
400 cc of glass (1020 grams) and 400 cc of resin = Total volume of 800 cc. The Vf would be 50% (400/800=.50)
Scenario #2:
400 cc of glass (1020 grams) and 300 cc of resin = Total volume of 700 cc. The Vf would be 57% (400/700=.57)
Both scenarios use the same volume and mass of fiber but have differing fiber volume fractions.
Also, as the Vf goes up for a specific volume of fiber the total thickness and weight must decrease. This happens because the total volume goes down as the Vf goes up (less resin=less volume and weight).
Make sense?