Technical Explanation: Cantilever Beam Analysis
A cantilever beam is fixed at one end and free at the other. The fixed end provides both a vertical reaction force and a restraining moment, making the beam statically determinate under transverse loading.
When a concentrated point load acts at the free end, the shear force is constant along the entire length, while the bending moment increases linearly from zero at the free end to its maximum value at the fixed support. The maximum deflection and slope also occur at the free end.
How to Use This Calculator
- Point Load (P): Enter the concentrated load applied at the free end in Newtons (N).
- Beam Length (L): Enter the length from the fixed support to the free end in millimeters (mm).
- Elastic Modulus (E): Material stiffness in MPa (e.g. 200,000 for structural steel).
- Moment of Inertia (I): Area moment of inertia in mm⁴.
- Distance to Extreme Fiber (c) – Optional: Required only if you want bending stress (mm).
Key Formulas Used
- Vertical reaction: R = P
- Maximum shear force: Vmax = P
- Maximum bending moment: Mmax = P L (at fixed end)
- Maximum deflection: δmax = P L³ / (3 E I) (at free end)
- Maximum bending stress: σmax = M c / I
Cantilever vs Simply Supported
For the same load and length, a cantilever develops four times the maximum moment and sixteen times the maximum deflection of a simply supported beam with a central point load. This is why cantilevers are generally limited to shorter spans or lighter loads.