Riveting terminology check: which one of the following statements is incorrect regarding nominal diameter, gross diameter, gross area, and hole size of rivets?

Introduction / Context:
Correct terminology for rivets and bolt holes is essential for net-section and bearing calculations. Misusing terms like nominal diameter, hole diameter, and gross area can lead to incorrect deductions and unsafe designs.

Given Data / Assumptions:

• Nominal diameter refers to the shank size before driving.
• Holes are drilled/punched slightly larger than nominal to allow fit-up.
• Gross area of a rivet refers to its shank area, not the hole area.

Concept / Approach:
Nominal diameter is the specified shank diameter of the rivet. The rivet hole is larger by a clearance (commonly ≈ 1.5 mm for standard sizes). The gross diameter of the rivet is often taken as the nominal shank diameter (while the gross diameter of the hole is the hole size). The gross area of a rivet is the cross-sectional area of the rivet itself (based on nominal diameter), whereas the plate's net area is reduced by the area of the hole, not by the rivet's gross area.

Step-by-Step Solution:
Review each statement against standard definitions.Identify that calling the rivet's gross area equal to the hole area is wrong—the hole belongs to the plate, not the rivet.Hence, option stating 'gross area of a rivet equals hole area' is incorrect.

Verification / Alternative check:
Design examples compute plate net area by subtracting n * (hole diameter) * thickness, while rivet strength checks use rivet shank area (based on nominal diameter) for shear/tension capacities.

Why Other Options Are Wrong:

• Option (a) and (d) align with standard practice.
• Option (b) is acceptable wording when explicitly referring to 'gross diameter of the hole'; the key incorrect statement remains the one equating rivet gross area to hole area.
• 'None of these' is incorrect since one statement is indeed wrong.

Common Pitfalls:

• Using hole area for rivet strength or rivet area for plate net-area deduction—these are distinct checks.

Final Answer:
The gross area of a rivet is the cross-sectional area of the rivet hole.