Length Of Kennedy Key Given Shear Stress In Key Calculator

Formula Used:

\[ l = \frac{Mtk}{\sqrt{2} \times ds \times bk \times \tau} \]

Transmitted Torque by Kennedy Key (Mtk):

N·m

Diameter of Shaft using Key (ds):

Width of Key (bk):

Shear Stress in Key (τ):

Length of Key (l):

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1. What is the Length of Kennedy Key Given Shear Stress in Key Formula?

The Length of Kennedy Key Given Shear Stress in Key formula calculates the required length of a Kennedy key based on transmitted torque, shaft diameter, key width, and allowable shear stress. This ensures the key can safely transmit torque without failure.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ l = \frac{Mtk}{\sqrt{2} \times ds \times bk \times \tau} \]

Where:

\( l \) — Length of Key (m)
\( Mtk \) — Transmitted Torque by Kennedy Key (N·m)
\( ds \) — Diameter of Shaft using Key (m)
\( bk \) — Width of Key (m)
\( \tau \) — Shear Stress in Key (Pa)

Explanation: The formula calculates the minimum key length required to safely transmit the specified torque without exceeding the allowable shear stress in the key material.

3. Importance of Key Length Calculation

Details: Proper key length calculation is essential for mechanical design to ensure reliable power transmission, prevent key failure, and maintain the integrity of shaft-hub connections in rotating machinery.

4. Using the Calculator

Tips: Enter transmitted torque in N·m, shaft diameter in meters, key width in meters, and allowable shear stress in Pascals. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a Kennedy key?
A: A Kennedy key is a type of parallel key used to connect rotating machine elements to shafts, transmitting torque through shear resistance.

Q2: Why is the √2 factor included in the formula?
A: The √2 factor accounts for the maximum shear stress distribution in the key under torsional loading conditions.

Q3: What are typical shear stress values for key materials?
A: Typical values range from 35-70 MPa for mild steel keys, but always consult material specifications for exact values.

Q4: Can this formula be used for other key types?
A: This specific formula is designed for Kennedy keys. Other key types (Woodruff, saddle, etc.) may require different calculations.

Q5: What safety factors should be considered?
A: Always apply appropriate safety factors based on application requirements, typically ranging from 1.5 to 4 for mechanical keys.