KEVOS® MAKEOS · Strength
Rotating Disc Stress and Burst Margin
What stress does spinning cause in this solid or bored disc, and how fast can it run before yield?
Maximum centrifugal stress in a rotating solid disc or a disc with a central bore, its rim speed, safety factor against yield and the speed at which yield is reached.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Outside diameter | mm | Outside diameter of the disc. |
| Bore diameter (0 = solid) | mm | Diameter of the central bore; 0 for a solid disc. |
| Speed | rpm | Highest running speed, including overspeed conditions. |
| Density | kg/m³ | Material density. |
| Poisson’s ratio | Poisson’s ratio. | |
| Yield strength | MPa | Minimum yield strength from the material certificate or specification. |
| Required safety factor | Factor of safety required by your design code, customer specification or company standard. |
Method and formulas
- ω = 2πn ÷ 60; outer radius b, bore radius a.
- Solid disc: σmax = (3 + ν) ÷ 8 × ρ ω² b² (at the centre).
- Bored disc: hoop stress at the bore σmax = (3 + ν) ÷ 4 × ρ ω² (b² + (1 − ν) ÷ (3 + ν) a²).
- Stress rises with speed squared: yield speed = n √(S_y ÷ σmax).
- Example: a 500 mm steel disc with a 50 mm bore at 3000 rpm reaches 40.034 MPa at the bore.
Limitations
- Uniform-thickness flat disc; holes, keyways and blades add stress concentrations.
- Elastic stress; burst occurs above yield but the margin depends on ductility.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check flywheels, saw blades, pulleys and impellers for overspeed
- Find the yield speed of a disc
- Compare solid and bored discs
Who it is for
- Design engineers
- Structural and mechanical engineers
- Engineering students
What you get
- Maximum stress and its location
- Rim speed
- Safety factor
- Speed at which yield is reached
Interpreting the result
- A small central bore roughly doubles the peak stress compared with a solid disc.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 187–190, 3000–3010. Topic reference; no source tables or recommended settings are reproduced.
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