Strength along and across the fiber (Toray T700S/epoxy, 60% fiber volume)
Where to buy| Direction | Tensile strength | Tensile modulus | Ratio to 0° strength |
|---|---|---|---|
| 0° (along fiber) | 415 ksi (2,860 MPa) | 19 Msi (134 GPa) | 100% |
| 90° (across fiber) | 12 ksi (81 MPa) | — | about 3% (calculated) |
| In-plane shear | 20 ksi (136 MPa) | — | about 5% (calculated) |
Toray T700S data sheet, composite properties normalised to 60% fiber volume, cured with epoxy at 130 °C. T800S gives 477 ksi / 11 ksi (3,290 / 79 MPa). Ratios calculated by The Aviation Point.
Carbon tape prepreg (HexPly 8552)
| Property | Carbon tapes |
|---|---|
| Resin content | 33–38% |
| Flow | 10–22% |
| Volatiles | 1.0% max |
| Gel time at 350 °F | 12–22 min |
HexPly 8552 data sheet, US units, 2020.
Why direction matters
The FAA handbook shows unidirectional against bidirectional material in Figure 7-1 and defines ply orientation from the warp or roll direction (p. 7-3). Quasi-isotropic layups mix 0°, ±45° and 90° plies so the laminate is similar in all directions (Figure 7-2).
A repair ply laid at the wrong angle puts the strong direction where the load does not go. Orientation is read from the SRM, never guessed from the damaged area.
Limits — when NOT to use this
- Ratios are for one fiber and resin pair.
- Not a ply design. The SRM gives plies, angles and cure.
Where to buy
AmericaDistributor coming soonOur partner for this region is on its way
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Distributors coming soon.
Sources
- Toray Composite Materials America, TORAYCA T700S Standard Modulus Carbon Fiber Data Sheet (Rev. 11/24/2025) — fiber and composite properties, tow sizes, resin compatibility.
- Toray Composite Materials America, TORAYCA T800S Intermediate Modulus Carbon Fiber Data Sheet (Rev. 04/13/2018) — fiber and composite properties, tow sizes, resin compatibility.
- Hexcel HexPly 8552 Product Data Sheet (US units, 2020) — neat resin properties, prepreg physical properties, cure procedure, storage life.
- FAA-H-8083-31B, AMT Handbook — Airframe, Volume 1 (2023), Chapter 7 — unidirectional and bidirectional (Figure 7-1); ply orientation (Figures 7-2 and 7-3, p. 7-3).
Educational reference only. not approved data. Always consult the applicable SRM, AMM, or AC 43.13-1B and your certifying authority.