A measure of the Poisson effect, the tendency of a material to expand in directions perpendicular to the direction of compression. Named after Siméon Poisson, it quantifies the relationship between lateral strain and axial strain.
| Property | Value | Description |
|---|---|---|
| Theoretical Limits | -1.0 to 0.5 | Thermodynamic constraints |
| Stable Materials | 0.0 to 0.5 | Most engineering materials |
| Auxetic Materials | < 0 | Negative Poisson's ratio |
Most metals exhibit Poisson's ratio values between 0.25 and 0.35, with approximately 0.3 being the most common. This is due to the atomic bonding characteristics and crystal structures of metallic materials.
| Material | Poisson's Ratio | Structure |
|---|---|---|
| Steel | 0.27 - 0.30 | BCC/FCC |
| Aluminum | 0.32 - 0.35 | FCC |
| Copper | 0.33 - 0.36 | FCC |
| Titanium | 0.30 - 0.34 | HCP |
| Cast Iron | 0.21 - 0.26 | BCC |
Poisson's ratio varies significantly across different material classes. Polymers, ceramics, and biological materials exhibit unique values based on their molecular structure and bonding mechanisms.
| Material | Poisson's Ratio | Behavior |
|---|---|---|
| Rubber | 0.49 - 0.50 | Near incompressible |
| Glass | 0.18 - 0.24 | Brittle |
| Cork | ~0.00 | Zero lateral strain |
| Auxetic Foam | -0.10 to -0.80 | Negative ratio |
| Concrete | 0.10 - 0.20 | Brittle |