1. What is Shaft Torsional Stiffness?

Torsional stiffness (k) is a measure of a shaft's resistance to twisting when subjected to torque. It's defined as the torque required to produce a unit angle of twist in the shaft.

2. How Does the Calculator Work?

The calculator uses the torsional stiffness equation:

Where:

• \( k \) — Torsional stiffness (N·m/rad)
• \( G \) — Shear modulus of the material (Pa)
• \( d \) — Diameter of the shaft (m)
• \( L \) — Length of the shaft (m)

Explanation: The equation shows that stiffness increases with material rigidity (G) and the fourth power of diameter, but decreases with shaft length.

3. Importance of Torsional Stiffness

Details: Torsional stiffness is critical in mechanical design to ensure shafts can transmit torque without excessive twist, which affects precision and can cause vibration issues.

4. Using the Calculator

Tips: Enter shear modulus in Pascals, diameter and length in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical shear modulus values?
A: For steel: ~80 GPa, aluminum: ~26 GPa, brass: ~40 GPa. Always check material specifications.

Q2: Why does diameter have such a large effect?
A: Stiffness depends on the polar moment of inertia, which is proportional to diameter^4.

Q3: How does hollow shaft stiffness compare?
A: For hollow shafts, replace d^4 with (d_outer^4 - d_inner^4) in the calculation.

Q4: What's the practical significance of torsional stiffness?
A: It affects natural frequency, power transmission efficiency, and precision in applications like drive shafts and robotic arms.

Q5: How to increase torsional stiffness?
A: Increase diameter (most effective), use stiffer material, or reduce shaft length.