1. What is Core Diameter of Screw?

The core diameter of screw is defined as the smallest diameter of the thread of the screw or nut. The term "minor diameter" replaces the term "core diameter" as applied to the thread of a screw. It is a critical parameter in mechanical design and stress analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( d_c \) — Core diameter of screw (m)
• \( M_{tt} \) — Torsional moment on screw (N·m)
• \( \tau \) — Torsional shear stress in screw (Pa)
• \( \pi \) — Archimedes' constant (approximately 3.1416)

Explanation: This formula calculates the minimum core diameter required to withstand a given torsional moment without exceeding the allowable torsional shear stress.

3. Importance of Core Diameter Calculation

Details: Accurate core diameter calculation is crucial for ensuring screw strength and preventing failure under torsional loads. It helps in proper sizing of screws for various mechanical applications.

4. Using the Calculator

Tips: Enter torsional moment in N·m and torsional shear stress in Pa. Both values must be positive numbers greater than zero for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is torsional shear stress?
A: Torsional shear stress is the shear stress produced in a material due to twisting forces or torque applied to it.

Q2: Why is core diameter important in screw design?
A: Core diameter determines the screw's ability to withstand torsional loads and prevents shear failure under applied torque.

Q3: What units should be used for input values?
A: Torsional moment should be in Newton-meters (N·m) and torsional shear stress in Pascals (Pa).

Q4: Can this formula be used for all types of screws?
A: This formula is generally applicable for solid circular screws subjected to pure torsion.

Q5: What factors affect torsional shear stress in screws?
A: Applied torque, material properties, and geometric dimensions (particularly core diameter) are the main factors affecting torsional shear stress.