Calculator Inputs
Use consistent units throughout. For example, g with g/cm³ gives cm³. kg with kg/L gives L. The page stays single-column, while fields adapt to screen size.
Example Data Table
| Method | Inputs | Calculated Vf | Vm | Vvoid | Composite Density |
|---|---|---|---|---|---|
| Mass and density | Fiber mass 700, matrix mass 300, fiber density 1.80, matrix density 1.20, void volume 20 | 59.0219% | 37.9427% | 3.0354% | 1.5177 |
| Weight fraction | Fiber weight fraction 65%, void fraction 2%, fiber density 1.75, matrix density 1.18, basis 1000 | 54.4879% | 43.5121% | 2.0000% | 1.4670 |
| Known volumes | Fiber volume 420, matrix volume 310, void volume 15, fiber density 1.90, matrix density 1.25 | 56.3758% | 41.6107% | 2.0134% | 1.5913 |
Formula Used
The main definition is Vf = Vfiber / Vcomposite. Fiber volume fraction measures how much of the total composite volume is occupied by reinforcement.
For the mass and density method, use Vfiber = mf / ρf and Vmatrix = mm / ρm. Then compute
Vcomposite = Vfiber + Vmatrix + Vvoid.
For the weight fraction method, convert fiber weight fraction wf into a solids-only fiber volume share with
(wf / ρf) / ((wf / ρf) + ((1 - wf) / ρm)).
Then adjust for voids using Vf = solids share × (1 - Vvoid fraction).
Composite density is estimated with ρc = (mf + mm) / Vcomposite. If modulus inputs are supplied, the page also estimates a simple longitudinal rule-of-mixtures modulus with
E1 ≈ VfEf + VmEm.
How to Use This Calculator
- Select the input method that matches your available manufacturing or test data.
- Enter fiber and matrix densities first, because every method depends on them.
- Fill in the method-specific fields. Add void information when you know porosity or trapped air volume.
- Optionally enter modulus values and a target fiber volume fraction for comparison.
- Press the calculate button. The results appear above the form, followed by a Plotly graph and export buttons.
FAQs
1) What does fiber volume fraction represent?
It is the percentage of total composite volume occupied by fiber. It differs from weight fraction because density changes how mass converts into actual space.
2) Why is volume fraction more useful than weight fraction?
Many laminate properties depend on geometry and packing, not only mass. Volume fraction better reflects stiffness trends, resin demand, and reinforcement distribution inside the part.
3) How do voids change the result?
Voids increase total composite volume without adding useful material. That lowers effective fiber and matrix volume fractions and usually reduces final quality.
4) Which units should I use?
Use any consistent unit system. If mass and density units match, the derived volume units will also be correct. Do not mix incompatible systems.
5) Can this page handle woven fabrics and chopped fibers?
Yes. The calculation is geometric, so it works for many reinforcement forms. Accuracy depends on using realistic measured density, mass, volume, and void data.
6) What is the solids fiber share output?
It shows the fiber percentage inside the solid material only, excluding voids. This helps compare reinforcement packing before porosity penalties are applied.
7) Why is an estimated modulus included?
It gives a quick directional check using a simple rule-of-mixtures approach. Treat it as a screening estimate, not a substitute for full laminate mechanics.
8) What usually causes unrealistic outputs?
The most common causes are inconsistent units, wrong density values, missing void data, and confusion between total laminate mass and dry fiber mass.