Torsional Shear Stress In Side-Crankshaft Below Flywheel For Max Torque Calculator

Torsional Shear Stress Formula:

\[ \tau = \frac{16}{\pi D_s^3} \times \sqrt{M_{bv}^2 + M_{bh}^2 + (P_t \times r)^2} \]

Diameter of Shaft Under Flywheel (Ds):

Vertical Bending Moment (Mbv):

N·m

Horizontal Bending Moment (Mbh):

N·m

Tangential Force at Crank Pin (Pt):

Distance Between Crank Pin And Crankshaft (r):

Shear Stress in Crankshaft Under Flywheel (τ):

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1. What is Torsional Shear Stress in Crankshaft?

Torsional shear stress in a crankshaft is the stress caused by twisting moments applied to the shaft. It's particularly important in the section below the flywheel where maximum torque conditions often occur, as this area experiences significant combined loading from bending and torsion.

2. How Does the Calculator Work?

The calculator uses the formula for combined torsional and bending stress:

\[ \tau = \frac{16}{\pi D_s^3} \times \sqrt{M_{bv}^2 + M_{bh}^2 + (P_t \times r)^2} \]

Where:

\( \tau \) — Shear stress in crankshaft under flywheel (Pa)
\( D_s \) — Diameter of shaft under flywheel (m)
\( M_{bv} \) — Vertical bending moment (N·m)
\( M_{bh} \) — Horizontal bending moment (N·m)
\( P_t \) — Tangential force at crank pin (N)
\( r \) — Distance between crank pin and crankshaft (m)
\( \pi \) — Mathematical constant (approximately 3.1416)

Explanation: This formula combines the effects of bending moments in both vertical and horizontal planes with the torsional moment created by the tangential force acting at a distance from the crankshaft center.

3. Importance of Shear Stress Calculation

Details: Accurate shear stress calculation is crucial for crankshaft design to ensure structural integrity under maximum torque conditions. It helps prevent fatigue failure and ensures the crankshaft can withstand the combined loading experienced during operation.

4. Using the Calculator

Tips: Enter all values in consistent SI units. The diameter must be greater than zero. All bending moments and forces should be positive values representing the magnitude of the loads.

5. Frequently Asked Questions (FAQ)

Q1: Why is the section below the flywheel critical?
A: This section often experiences the highest combined stresses due to the flywheel's mass and the torque transmission, making it a common failure point.

Q2: What is a typical safe value for shear stress in crankshafts?
A: Safe values depend on the material, but typically range from 40-80 MPa for steel crankshafts, though always consult specific material specifications.

Q3: How does the tangential force affect the stress?
A: The tangential force creates a torsional moment that combines with bending moments, significantly increasing the shear stress in the crankshaft.

Q4: Are there limitations to this calculation?
A: This formula assumes a solid circular shaft and doesn't account for stress concentrations, fatigue, or temperature effects which may be important in actual applications.

Q5: Should safety factors be applied to the result?
A: Yes, engineering designs typically apply appropriate safety factors based on the application, material properties, and loading conditions.