Diameter Of Centre Crankshaft At Juncture Of Right Crankweb For Max Torque Given Moments Calculator

Formula Used:

\[ ds1 = \left( \frac{16}{\pi \cdot \tau} \cdot \sqrt{Mb^2 + Mt^2} \right)^{1/3} \]

Shear Stress in Shaft at Crankweb Joint (τ):

Resultant Bending Moment at Crankweb Joint (Mb):

N·m

Torsional Moment at Crankweb Joint (Mt):

N·m

Diameter of Crankshaft at Crankweb Joint (ds1):

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1. What is the Diameter Calculation Formula?

The formula calculates the required diameter of a centre crankshaft at the juncture of the right crankweb for maximum torque conditions, considering both bending and torsional moments along with material shear stress.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ ds1 = \left( \frac{16}{\pi \cdot \tau} \cdot \sqrt{Mb^2 + Mt^2} \right)^{1/3} \]

Where:

\( ds1 \) — Diameter of crankshaft at crankweb joint (m)
\( \tau \) — Shear stress in shaft at crankweb joint (Pa)
\( Mb \) — Resultant bending moment at crankweb joint (N·m)
\( Mt \) — Torsional moment at crankweb joint (N·m)
\( \pi \) — Mathematical constant pi (approximately 3.1416)

Explanation: This formula combines the effects of both bending and torsional stresses to determine the minimum required shaft diameter that can safely withstand the applied loads.

3. Importance of Crankshaft Diameter Calculation

Details: Proper crankshaft diameter calculation is crucial for engine design and reliability. An undersized crankshaft may fail under operational loads, while an oversized one adds unnecessary weight and cost.

4. Using the Calculator

Tips: Enter shear stress in Pascals, bending moment and torsional moment in Newton-meters. All values must be positive numbers with shear stress greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: Why is this specific formula used for crankshaft diameter calculation?
A: This formula combines both bending and torsional stress effects using the maximum shear stress theory, which is appropriate for ductile materials like crankshaft steel.

Q2: What are typical shear stress values for crankshaft materials?
A: Typical allowable shear stresses for crankshaft steel range from 40-100 MPa, depending on the material grade and safety factors applied.

Q3: How are the bending and torsional moments determined?
A: These are calculated from engine dynamics including combustion forces, inertial forces, and the geometry of the crankshaft and connecting rod.

Q4: Does this calculation consider fatigue loading?
A: This formula provides the diameter for static loading conditions. For fatigue considerations, additional factors and safety margins should be applied.

Q5: Can this calculator be used for other shaft applications?
A: While derived for crankshafts, the formula is generally applicable to any shaft subjected to combined bending and torsion.