What is Transverse Stiffness of Composites?

Transverse stiffness (Young's modulus, E_T) defines the mechanical performance of unidirectional fiber-reinforced composites perpendicular to the fiber direction. The Halpin‑Tsai model is the industry‑standard semi‑empirical method, adopting an adjustable geometry coefficient ξ for different fiber shapes.

Halpin‑Tsai Formula

η = (E_f / E_m − 1) / (E_f / E_m + ξ)
E_T = E_m × (1 + η·V_f) / (1 − η·V_f)

Where:
• E_T = Transverse modulus (GPa)
• E_f = Fiber modulus (GPa)
• E_m = Matrix modulus (GPa)
• V_f = Fiber volume fraction (0–1)
• ξ = Empirical geometry coefficient
Recommended value: ξ = 2 for round fibers (transverse direction)

Enter Parameters

Fiber Young's Modulus E_f (GPa) Matrix Young's Modulus E_m (GPa) Fiber Volume Fraction V_f (0–1) Empirical Geometry Coefficient ξ

E_T = ? GPa

Reference Example

Carbon / Epoxy unidirectional composite:
E_f = 230 GPa , E_m = 3.5 GPa , V_f = 0.60 , ξ = 2.00
→ E_T = 12.91 GPa

Engineering Applications

Transverse modulus prediction for UD composite laminates
FEA material input for aerospace & automotive structures
Parameter comparison for different fiber cross‑sections
Composite material teaching & research calculation

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