Diameter of Bolt under Load Calculator

Bolt Diameter Formula:

\[ d_b = \sqrt{\frac{F_{Stud} \times 4}{\pi \times n \times f_t}} \]

Load by Stud:

Number of Bolts:

Allowable Stress:

N/m²

Tolerance:

Bolt Diameter (m):

Tolerance Range (m):

1. What is a Bolt Diameter Calculator?

Definition: This calculator determines the required bolt diameter based on the applied load, number of bolts, and allowable stress in the material.

Purpose: It helps engineers and designers select appropriate bolt sizes for mechanical connections under load.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ d_b = \sqrt{\frac{F_{Stud} \times 4}{\pi \times n \times f_t}} \]

Where:

\( d_b \) — Bolt diameter (meters)
\( F_{Stud} \) — Load by stud (Newtons)
\( n \) — Number of bolts
\( f_t \) — Allowable stress in stud material (N/m²)
\( \pi \) — Mathematical constant (3.14159...)

Explanation: The formula calculates the minimum required bolt diameter to safely distribute the load across all bolts without exceeding the material's allowable stress.

3. Importance of Bolt Diameter Calculation

Details: Proper bolt sizing ensures structural integrity, prevents mechanical failure, and maintains safety factors in loaded connections.

4. Using the Calculator

Tips: Enter the load in Newtons, number of bolts, allowable stress (N/m²), and tolerance percentage (default ±5%). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the purpose of the tolerance field?
A: The tolerance (±%) provides a range of acceptable diameters around the calculated value for manufacturing and safety considerations.

Q2: How do I determine the allowable stress for my material?
A: Consult material specifications or engineering references for yield strength and apply appropriate safety factors.

Q3: Does this calculator account for dynamic or fatigue loads?
A: No, this calculates for static loads only. For dynamic loading, additional factors must be considered.

Q4: What if my bolts have different strength grades?
A: Use the lowest allowable stress among all bolts in the connection for conservative design.

Q5: How does number of bolts affect the result?
A: More bolts distribute the load, allowing smaller diameters, while fewer bolts require larger diameters to handle the same load.