Number of bolts given torque resisted by n bolts Calculator

Number of Bolts Formula:

\[ n = \frac{8 \times T_{bolt}}{f_s \times \pi \times d_{bolt}^2 \times d_{pitch}} \]

Torque resisted by bolt (T):

N·m

Shear Stress in Bolt (fₛ):

Diameter of Bolt (d):

Diameter of bolt pitch circle:

Tolerance:

Number of Bolts (n):

1. What is the Number of Bolts Calculator?

Definition: This calculator determines the number of bolts required to resist a given torque based on bolt diameter, shear stress, and pitch circle diameter.

Purpose: It helps mechanical engineers and designers determine the appropriate number of bolts for flanged connections and other torque-resisting applications.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ n = \frac{8 \times T_{bolt}}{f_s \times \pi \times d_{bolt}^2 \times d_{pitch}} \]

Where:

\( n \) — Number of bolts
\( T_{bolt} \) — Torque resisted by bolt (N·m)
\( f_s \) — Shear stress in bolt (Pa)
\( d_{bolt} \) — Diameter of bolt (m)
\( d_{pitch} \) — Diameter of bolt pitch circle (m)

Explanation: The formula calculates the number of bolts needed to distribute the torque evenly based on each bolt's shear capacity.

3. Importance of Bolt Calculation

Details: Proper bolt calculation ensures joint integrity, prevents overloading of individual bolts, and maintains safety factors in mechanical connections.

4. Using the Calculator

Tips: Enter the torque value, shear stress, bolt diameter, and pitch circle diameter. The optional tolerance field (default ±5%) provides a range of acceptable values.

5. Frequently Asked Questions (FAQ)

Q1: What is bolt pitch circle diameter?
A: It's the diameter of the circle that passes through the center of all the bolt holes in a bolted joint.

Q2: How do I determine shear stress for my bolts?
A: Shear stress depends on bolt material and grade. Typical values range from 140-350 MPa for steel bolts.

Q3: Why include a tolerance percentage?
A: The tolerance accounts for variations in material properties, manufacturing tolerances, and safety factors.

Q4: Can I use this for metric and imperial units?
A: Yes, but ensure all units are consistent (all metric or all imperial) when entering values.

Q5: What if my calculated number isn't a whole number?
A: Always round up to the nearest whole number since you can't have a fraction of a bolt.