Analysis & loading · Seismic & dynamic
Impact load from a dropped mass calculator
Equivalent static force from a mass dropped onto an elastic member: F = W(1 + √(1 + 2h/δst)).
Standard: Energy method (elastic system)
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Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Mass | 200 | kg |
| Drop height | 50 | mm |
| Member stiffness | 2.5 | kN/mm |
| Member capacity | 30 | kN |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Weight | 1.96 | kN |
| Static deflection | 0.785 | mm |
| Impact factor 1 + √(1 + 2h/δst) | 12.33 | |
| Equivalent force | 24.20 | kN |
| Peak deflection | 9.68 | mm |
- ✓ Peak force ≤ capacity
Method, formulas and assumptions
- Weight = 200*9.81/1000 = 1.962 kN
- Static deflection = 1.962/2.5 = 0.7848 mm
- Impact factor 1 + √(1 + 2h/δst) = 1+SQRT(1+2*50/0.7848) = 12.332
- Equivalent force = 1.962*12.332 = 24.196 kN
- Peak deflection = 24.196/2.5 = 9.6784 mm
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.