Core Diameter of Bolts of Big End Cap of Connecting Rod Calculator

Core Diameter Formula:

\[ d_c = \sqrt{\frac{2 \times P_i}{\pi \times \sigma_t}} \]

Core Diameter (m):

1. What is Core Diameter of Bolts of Big End Cap?

Definition: This calculator determines the minimum core diameter required for the bolts in the big end cap of a connecting rod to withstand the inertia forces.

Purpose: It ensures the bolts are strong enough to handle the dynamic loads in an engine's connecting rod assembly.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ d_c = \sqrt{\frac{2 \times P_i}{\pi \times \sigma_t}} \]

Where:

\( d_c \) — Core diameter of bolt (meters)
\( P_i \) — Inertia force on bolts (Newtons)
\( \sigma_t \) — Permissible tensile stress (Pascals)

Explanation: The formula calculates the minimum diameter needed to distribute the inertia force across the bolt's cross-sectional area without exceeding the material's tensile strength.

3. Importance of Core Diameter Calculation

Details: Proper bolt sizing prevents catastrophic engine failure due to bolt fracture under dynamic loads.

4. Using the Calculator

Tips: Enter the inertia force in Newtons, permissible tensile stress in Pascals, and safety factor (±5%). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is inertia force in connecting rods?
A: The force caused by the reciprocating mass of the piston and connecting rod during engine operation.

Q2: How is permissible tensile stress determined?
A: It's typically the yield strength of the bolt material divided by a safety factor.

Q3: Why include a safety factor?
A: To account for dynamic loads, material variations, and manufacturing tolerances (±5% is typical).

Q4: What units should I use?
A: Use Newtons for force, Pascals for stress, and meters for diameter.

Q5: How does this relate to bolt thread size?
A: The core diameter is the smallest diameter of the threaded portion - select standard bolts with core diameter equal to or larger than calculated.