Shear Stress on Flat Key Calculator

Shear Stress Formula:

\[ \text{Shear Stress} = \frac{2 \times \text{Torque Transmitted by Shaft}}{\text{Width of Key} \times \text{Diameter of Shaft} \times \text{Length of Key}} \]

Torque Transmitted by Shaft (T):

N·m

Width of Key (bk):

Diameter of Shaft (ds):

Length of Key (l):

Shear Stress (τ):

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1. What is Shear Stress on Flat Key?

Shear stress on a flat key is the stress that tends to cause deformation of the key material by slippage along a plane parallel to the imposed stress. It's a critical parameter in mechanical design to ensure the key can withstand the transmitted torque without failure.

2. How Does the Calculator Work?

The calculator uses the shear stress formula:

\[ \tau = \frac{2 \times T}{b_k \times d_s \times l} \]

Where:

\( \tau \) — Shear Stress (Pa)
\( T \) — Torque Transmitted by Shaft (N·m)
\( b_k \) — Width of Key (m)
\( d_s \) — Diameter of Shaft (m)
\( l \) — Length of Key (m)

Explanation: The formula calculates the shear stress acting on a flat key based on the transmitted torque and key dimensions.

3. Importance of Shear Stress Calculation

Details: Accurate shear stress calculation is crucial for ensuring mechanical components can safely transmit power without failure. It helps engineers select appropriate materials and dimensions for keys in power transmission systems.

4. Using the Calculator

Tips: Enter torque in Newton-meters, and all dimensions in meters. All values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical allowable shear stress for key materials?
A: Allowable shear stress varies by material. For mild steel, it's typically 40-60 MPa; for alloy steels, it can be 80-100 MPa or higher.

Q2: How does key length affect shear stress?
A: Longer keys distribute the shear force over a larger area, reducing shear stress. Shorter keys concentrate the stress, requiring stronger materials.

Q3: What happens if shear stress exceeds material limits?
A: Excessive shear stress can cause key failure through shearing, leading to power transmission interruption and potential damage to connected components.

Q4: Are there other failure modes for keys besides shear?
A: Yes, keys can also fail through crushing (compressive stress) or wear over time, especially if there's relative motion between components.

Q5: When should I use a flat key vs other key types?
A: Flat keys are suitable for light to moderate torque applications. For higher torque requirements, consider saddle keys, tangent keys, or splined connections.