A solid steel shaft is to transmit a torque of 10kNm. If the shearing ...
To determine the minimum diameter of a solid steel shaft that can safely transmit a torque of 10 kNm without exceeding a shearing stress of 45 MPa, we can use the following formula:
1. Torque FormulaThe relationship between torque (T), shearing stress (τ), and the diameter (d) of the shaft is given by the equation:
Where:
- T = Torque in Nm
- τ = Shearing stress in MPa
- d = Diameter in m
2. Convert UnitsFirst, we need to convert the torque from kNm to Nm:
Next, convert the shearing stress from MPa to Pa (1 MPa = 1,000,000 Pa):
- τ = 45 MPa = 45 × 1,000,000 Pa = 45,000,000 Pa
3. Rearranging the FormulaNow, we can rearrange the torque formula to solve for d:
4. Substituting ValuesNow substitute the values of T and τ into the equation:
- d^3 = (16 × 10,000) / (π × 45,000,000)
5. CalculationCalculating the above expression:
- d^3 = (160,000) / (141,372.6) ≈ 1.131 m^3
Now take the cube root to find d:
- d ≈ (1.131)^(1/3) ≈ 0.105 m
- d ≈ 105 mm
6. ConclusionThus, the minimum diameter of the shaft needed to safely transmit a torque of 10 kNm without exceeding a shearing stress of 45 MPa is approximately: