UW Composites Analysis · Material Builder
Composite Micromechanics Calculator: Rule of Mixtures and Halpin–Tsai
Mix fibers with a resin and see how the composite properties change. The Material Builder estimates density, stiffness, strength and thermal properties from the fiber, the resin, the fiber volume fraction and the void content, and draws a picture of the material as you go.
Open the Material Builder →Free, runs in your browser, no installation or login.
What you can do
- Choose carbon (AS4, IM7), glass (E-glass, S-2 glass) or aramid (Kevlar 49) fibers in an epoxy resin, or mix two fibers in a hybrid.
- Set the fiber volume fraction and void content with sliders and see density, weight fractions and properties update at once.
- Plot any property against fiber, resin or void content, or against another property.
- Save materials and compare them side by side, with a picture of each.
- Most other pages use the material you build, including the Laminate Builder and the Cure Simulation.
How it works
Vm = 1 − Vf − Vv, ρ = Vf ρf + Vm ρm
Composition and density; voids have no mass.
E1 = Vf Ef1 + (1 − Vf) Em′
Rule of mixtures along the fibers, with the resin modulus reduced for porosity.
P / Pm′ = (1 + ξη Vf) / (1 − η Vf), η = (Pf/Pm′ − 1) / (Pf/Pm′ + ξ)
Halpin–Tsai for the transverse modulus E2 (ξ = 2) and shear modulus G12 (ξ = 1).
Fiber and resin properties come from manufacturer datasheets and published characterization data; each value and its source is listed in the app. Strengths are teaching estimates from a simple constituent model. Every page of the app lists its full equations and sources under Equations.
Questions to explore
- Why does stiffness along the fibers grow linearly with fiber content, but stiffness across the fibers does not?
- How much does 5% porosity cost in stiffness, and how much in strength?
- Where do glass, aramid and carbon composites sit in stiffness for their weight?