Design of riveted joints – Definition of efficiency In machine design, the efficiency of a riveted joint is defined as which ratio with respect to the original unperforated plate?

Introduction / Context:Riveted joints are evaluated by comparing the capacity of the perforated, riveted section against the capacity of the original unperforated plate. This comparison leads to a dimensionless efficiency that indicates how much of the base plate strength is retained by the joint.

Given Data / Assumptions:

• Tensile loading is along the joint line.
• Joint strength is governed by the least of tearing, shearing, and bearing strengths over one pitch length.
• Solid plate strength is based on full plate section without holes.

Concept / Approach:Joint efficiency η measures how effectively the joint transmits load compared to the parent plate. It is defined as a ratio, not a difference. Selecting the minimum failure mode ensures a conservative evaluation.

Step-by-Step Solution:Compute solid plate strength: P_solid = plate_thickness * plate_width * allowable_stress.Compute joint strength per pitch: P_joint = minimum of (tearing capacity through net section, shear capacity of rivets, bearing capacity).Define efficiency: η = P_joint / P_solid.Interpretation: 0 < η ≤ 1, with higher values indicating better utilization of plate strength.

Verification / Alternative check:Design codes and textbooks consistently define efficiency as a ratio of capacities, confirming the correct option.

Why Other Options Are Wrong:(B) inverts the ratio; (C) is a geometric parameter, not efficiency; (D) and (E) restrict to partial modes and ignore the weakest-link principle.

Common Pitfalls:Forgetting to use net section for tearing; ignoring bearing limits; comparing per-pitch strengths to the correct reference section.

Final Answer:The ratio of the strength of the joint to the strength of the solid (unrivettted) plate