[FONT=Calibri][COLOR=black]Good morning,[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Following a previous post (http://www.compositescentral.com/showthread.php?p=39589#post39589) on fiber volume fraction calculations, I would be very grateful if someone could please clarify how to determine this parameter when several materials with different properties are involved in a laminate.[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]All of the explanations gathered in the referred post are related to a laminate combining one fabric and one resin.[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Let us suppose you have two fabrics (e.g. Biaxial carbon fiber (CF) with different aereal weights but could be any other) involved and one resin:[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Layer 1 – Biaxial CF 300gsm – 75g[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Layers 2 and 3 – Biaxial CF 100 gsm – 50g[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Layer 4 – Biaxial CF 300gsm – 75g[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Epoxy Resin – 120g[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]I assume you cannot calculate Vf for the entire composite and you should find a Vf for the different layers (1 and 4; 2 and 3). [/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Key question: What resin weight values should be included in the calculations? Assume 25% for each layer? (i.e. 60g for layers 1 and 4 / 2 and 3)[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Thanks in advance for your help,[/FONT][/COLOR]
[FONT=Calibri][COLOR=black]Regards,[/FONT][/COLOR]
Using a numerical example and assuming 1,8g/cc for the Carbon Fibre density:
Layer 1: Carbon Fibre (300 gsm Areal weight), 300g -> Volume: 166,7 cc
Layer 2: Carbon Fibre (100 gsm Areal weight), 100g -> Volume: 55,6 cc
Layer 3: As Layer 2
Layer 4: As Layer 1
Resin: 400g @ 1,25g/cc -> Volume: 320 cc
Total Volume: (166,7x2) + (55,6x2) + 320 = 764,6 cc
How would Vf be calculated?
[(166,7x2) + (55,6x2)] / (746,6) = 0,58 … would be the usual approach …
However, volumen of fibre in Layers 1/4 and 2/3 is different as shown before … Should another different approach be adopted?
Help would be sincerely appreciated,
Thanks,