PHYSICS · Multi-part · Fermi University Physics · Fluids & Continuum Physics · Solid continuum mechanics and complex fluids · Solid continuum mechanics and complex fluids
Bending, Ringing, Breaking and Flowing, Ch Fracture: stress concentration, cracks and toughness
Problem
A wide aluminium plate (200mm across, much wider than either hole below) carries a remote tensile stress σ=60MPa. Two engineers each drill a single circular hole through a separate identical plate to relieve an assembly clash: Engineer A drills a 2mm diameter hole, Engineer B drills a 20mm diameter hole. Engineer A argues that the smaller hole removes far less material and must weaken the plate less, so the smaller hole is the safer choice.
((a)) Find the maximum tensile stress at the edge of each hole.
((b)) State whether the stress concentration factor depends on the hole diameter here, and explain in one or two sentences why Engineer A's reasoning is flawed.