Composites Database
Fibre-reinforced laminates — light, stiff and strongly directional, so the fibre direction belongs in every figure.
Overviewwhat this group covers and how to read the numbers
A fibre-reinforced laminate gets its properties from two materials working together: stiff fibres carrying the load and a polymer matrix holding them in place and spreading it between them. Glass, carbon and aramid are the three fibres that cover most engineering use, and the difference between them is mostly one of stiffness against toughness.
The consequence, and the thing every figure on these pages is shaped by, is that a laminate has no single strength. Its properties run along the fibres and across them, and the two are not close: glass laminate carries about 28 times more load along the fibres than across them, carbon about 58 times. A number quoted without a direction is not a conservative figure — it is a figure for a direction the load may never travel in.
Fibre volume fraction matters just as much. These entries are all unidirectional laminates at a stated fraction, which is also what fixes their density — change the fraction or the layup and every figure on the page changes with it. That is why the fraction is printed next to the values rather than buried in a note.
Joining is where laminates most often disappoint. A bolted joint concentrates load at the hole, in the one direction the material is weakest, and it does it through a section that is usually thin. Bonding spreads the same load over an area instead. Where a bolt cannot be avoided, the bearing area and the edge distance are the two dimensions that decide whether the joint works.
Wood-based panels — plywood, MDF and OSB — are composites too, and this database files them under Wood / Engineered rather than here. They are classified by their base material, which is what a reader looking for a board is looking for, and both groups link to each other so the split is visible rather than silent.
composite3 entries
Density comparisonevery composites entry on one scale
Weight calculator| Material | Group | Density (g/cm³) | kg/m³ |
|---|---|---|---|
| Aramid Fibre Composite (AFRP) | composite | 1.38 | 1380 |
| Carbon Fibre Composite (CFRP) | composite | 1.6 | 1600 |
| Glass Fibre Composite (GFRP) | composite | 2.1 | 2100 |
Densest entry: Glass Fibre Composite (GFRP) at 2.1 g/cm³. Lightest: Aramid Fibre Composite (AFRP) at 1.38 g/cm³. All figures are for a unidirectional laminate at the stated fibre volume fraction — not for a woven or quasi-isotropic layup.
Common applicationswhere these materials are actually used
Frequently asked questionsabout composites selection
Why is there no single strength figure for carbon fibre?
Because there is no such number. The strength of a laminate depends on the fibre, the matrix, the fibre volume fraction and the direction the load arrives in — the same carbon laminate is 2,860 MPa along the fibres and 49 MPa across them. Any published single figure is a figure for a specific layup and direction that the source has stated somewhere.
Can I bolt a composite instead of bonding it?
Yes, with care. A bolt concentrates load right where the laminate is weakest and thinnest, so the joint needs generous edge distance, a large bearing area under the washer, and a design load well below the laminate's own strength. Bonding spreads the same load over an area and is normally the better answer where the geometry allows it.
Why are plywood and MDF not listed as composites here?
They are composites, and the omission is a filing decision rather than a technical one: this database groups materials by their base material, and those panels are wood. They are listed in full under Wood / Engineered, with the properties they do have, and both pages point at each other.
Is a composite lighter than aluminium?
Per unit of stiffness and strength, usually yes — the density comparison above ranks every family on one scale. But a composite part is not interchangeable with an aluminium one of the same shape, because the stiffness is directional. The comparison that matters is a part designed in each material, not a material against a material.