1. What is the Shaft Diameter Formula?

The shaft diameter formula calculates the minimum diameter required for a solid circular shaft to safely transmit a given torque without exceeding the allowable shear stress of the material.

2. How Does the Calculator Work?

The calculator uses the shaft diameter formula:

Where:

• \( d \) — Shaft diameter (m)
• \( t \) — Applied torque (N·m)
• \( \tau \) — Allowable shear stress (Pa)
• \( \pi \) — Mathematical constant pi (~3.14159)

Explanation: The formula is derived from the torsion equation for circular shafts, ensuring the maximum shear stress doesn't exceed the material's allowable stress.

3. Importance of Shaft Diameter Calculation

Details: Proper shaft sizing is critical in mechanical design to ensure sufficient strength to transmit torque while avoiding excessive size that increases weight and cost.

4. Using the Calculator

Tips: Enter torque in N·m and allowable shear stress in Pa. Both values must be positive numbers. The result will be the minimum required diameter in meters.

5. Frequently Asked Questions (FAQ)

Q1: What units should I use for this calculation?
A: The calculator uses SI units: torque in Newton-meters (N·m) and stress in Pascals (Pa). The result is in meters (m).

Q2: Does this formula work for hollow shafts?
A: No, this formula is specifically for solid circular shafts. A different formula is needed for hollow shafts.

Q3: How do I determine the allowable shear stress?
A: The allowable shear stress depends on the material. It's typically a fraction (often 0.5-0.6) of the material's yield strength in shear.

Q4: What safety factors should I consider?
A: The calculated diameter is the theoretical minimum. Always include appropriate safety factors based on application requirements.

Q5: Can I use this for alternating torque loads?
A: For fatigue loading conditions, additional factors like stress concentration and endurance limits must be considered.