KEVOS® MAKEOS · Strength
Impact Load on a Beam
What stress and deflection does a dropped weight cause in this beam?
Static deflection, impact factor, dynamic deflection and dynamic bending stress when a weight falls onto a simply supported beam at mid-span or onto a cantilever tip.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Support | choice | Support arrangement and impact point. |
| Falling mass | kg | Mass of the falling object. |
| Drop height above the beam | mm | Height it falls before touching the beam. |
| Span (or cantilever length) | mm | Span, or cantilever length. |
| Elastic modulus | GPa | Elastic modulus from the material data sheet (steel is typically about 200 GPa). |
| Second moment of area | mm⁴ | Second moment of area of the beam section. |
| Distance to extreme fibre | mm | Neutral axis to extreme fibre. |
| Allowable stress | MPa | Allowable stress for this (often accidental) load case. |
Method and formulas
- Static: simply supported δst = WL³ ÷ 48EI, M = WL/4; cantilever δst = WL³ ÷ 3EI, M = WL.
- Impact factor = 1 + √(1 + 2h ÷ δst).
- Dynamic deflection and stress = factor × static values.
- Example: 20 kg dropped 100 mm on the default beam gives an impact factor of 99.946 and 61.258 MPa.
Limitations
- The beam mass and local indentation are ignored (conservative for light beams, less so for heavy ones).
- Elastic response assumed; above yield the energy is absorbed plastically.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check guards, stops and platforms against dropped objects
- Estimate shock loading on a beam
- Compare stiff and flexible supports
Who it is for
- Design engineers
- Structural and mechanical engineers
- Engineering students
What you get
- Static deflection and stress
- Impact factor
- Dynamic deflection and stress
Interpreting the result
- A more flexible beam has a lower impact factor; a stiff beam sees higher dynamic stress.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 278. Topic reference; no source tables or recommended settings are reproduced.
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