1. What is Shaft Diameter Calculation?

The shaft diameter calculation determines the minimum diameter required for a shaft to safely withstand combined bending and torsional loads without exceeding material stress limits.

2. How Does the Calculator Work?

The calculator uses the shaft diameter formula:

Where:

• \( d \) — Shaft diameter (m)
• \( M \) — Bending moment (N·m)
• \( \tau \) — Allowable shear stress (Pa)
• \( T \) — Torque (N·m)
• \( \sigma \) — Allowable tensile stress (Pa)

Explanation: The equation combines the effects of bending and torsion using the maximum shear stress theory (Guest's theory).

3. Importance of Shaft Diameter Calculation

Details: Proper shaft sizing is critical for mechanical design to ensure sufficient strength while avoiding excessive material use. Undersized shafts may fail, while oversized shafts increase cost and weight unnecessarily.

4. Using the Calculator

Tips: Enter all values in consistent SI units. Bending moment and torque must be ≥0, while stress values must be >0. The calculator provides diameter in meters.

5. Frequently Asked Questions (FAQ)

Q1: What if I only have bending or only torsion?
A: For pure bending, set T=0. For pure torsion, set M=0. The equation simplifies accordingly.

Q2: How do I determine allowable stresses?
A: Allowable stresses are typically a fraction (safety factor) of the material's yield strength. Consult material specifications.

Q3: Does this account for fatigue?
A: No, this is for static loading. Fatigue analysis requires additional considerations like stress concentrations and load cycles.

Q4: What about hollow shafts?
A: This formula is for solid shafts. Hollow shafts require different calculations considering the inner and outer diameters.

Q5: How conservative is this calculation?
A: This is a basic calculation. Real-world designs should consider factors like keyways, stress concentrations, and combined loading effects.