Name the stress at a local contact between two members\n\nA localized compressive stress developed at the small area of contact between two mating members (such as a pin in a lug or a rivet in a plate) is called:

Introduction / Context:
Machine and structural joints often transfer load through small contact areas, for example pins, rivets, and bolts in holes. The primary compressive stress in the contact patch must be identified and limited to avoid permanent deformation.

Given Data / Assumptions:

• Two members pressed together over a finite, relatively small area (hole–pin, rivet–plate, key–keyway).
• Load predominantly compressive and normal to the contact patch.
• Elastic design intent with allowable bearing stresses.

Concept / Approach:
The stress of interest is called crushing stress or bearing stress. It represents average compressive stress over the projected contact area (usually hole diameter times plate thickness for design).

Step-by-Step Solution:
Define projected bearing area A_bearing = d * t (for a plate of thickness t and pin/rivet diameter d).Average bearing stress: σ_bearing = P / A_bearing.Design requires σ_bearing ≤ allowable bearing stress to prevent local yielding or hole elongation.

Verification / Alternative check:
Observe failure modes in joints: excessive bearing stress causes ovalization of holes and plastic flow around the contact, distinct from shear failure of fasteners or tearing across net sections.

Why Other Options Are Wrong:
Tensile and bending stresses are not the primary local contact stresses. Shear stress is relevant to fastener shear failure, not the compressive contact between parts. Torsional stress is unrelated to this local phenomenon.

Common Pitfalls:
Using bolt shear area instead of projected bearing area; ignoring edge distance effects; confusing bearing with contact Hertzian stress in curved contacts—here we refer to average design bearing stress.

Final Answer:
crushing (bearing) stress