What is Young’s Modulus (Modulus of Elasticity)?
Young’s Modulus (or modulus of elasticity) is a measure of a material’s stiffness. It tells you how much a material will deform elastically under a given load. A high Young’s Modulus means a stiff material (like steel); a low value means a flexible material (like rubber).
Formula: E = σ / ε
- E = Young’s Modulus
- σ = stress (force per unit area)
- ε = strain (proportional deformation)
Young’s Modulus for Common Engineering Materials
| Material | Young’s Modulus (GPa) | Young’s Modulus (Mpsi) |
|---|---|---|
| Metals | ||
| Steel (carbon, alloy) | 200–210 | 29–30 |
| Stainless Steel | 190–200 | 27.5–29 |
| Titanium (Ti-6Al-4V) | 110–120 | 16–17.5 |
| Aluminum Alloys | 69–79 | 10–11.5 |
| Brass | 90–110 | 13–16 |
| Copper | 110–120 | 16–17.5 |
| Magnesium Alloys | 41–45 | 6–6.5 |
| Cast Iron | 100–160 | 14.5–23 |
| Plastics | ||
| Nylon (PA66) | 2–4 | 0.3–0.6 |
| Polycarbonate (PC) | 2.3–2.4 | 0.33–0.35 |
| ABS | 1.8–2.5 | 0.26–0.36 |
| Polypropylene (PP) | 1.3–1.8 | 0.19–0.26 |
| Polyethylene (HDPE) | 0.7–1.4 | 0.10–0.20 |
| Acetal (POM) | 2.8–3.2 | 0.41–0.46 |
| PTFE (Teflon) | 0.4–0.5 | 0.06–0.07 |
| Delrin (POM) | 3.1 | 0.45 |
| PEEK | 3.6–4.0 | 0.52–0.58 |
| Acrylic (PMMA) | 2.4–3.3 | 0.35–0.48 |
| Composites | ||
| Carbon Fiber Composite (unidirectional) | 130–180 | 19–26 |
| Fiberglass Composite | 20–50 | 3–7 |
| Wood (oak, along grain) | 11–12 | 1.6–1.7 |
| Ceramics | ||
| Alumina (Al₂O₃) | 300–400 | 43.5–58 |
| Silicon Carbide (SiC) | 400–450 | 58–65 |
Key Considerations for Young’s Modulus
- Temperature dependence: Young’s Modulus decreases with increasing temperature, especially for polymers.
- Anisotropy: Many materials (especially composites and wood) have different moduli in different directions.
- Design for stiffness vs. strength: Sometimes you need a stiff part (high E) even if ultimate strength isn’t the primary concern. E.g., a long beam that deflects too much.
- Yield strength is separate. A material can be stiff (high E) but have a low yield strength, meaning it deforms little but permanently fails early.
Related: Material Stock Category | Aluminum Alloy Comparison | Stainless Steel Types