🔍 Key Concepts

• Purpose of a crack stopper in metal plating or structure • How drilling a hole at the end of a crack affects stress concentration and crack propagation • Why it might be necessary to treat both ends of a crack rather than just one

💭 Think About

• Think about how a crack in a plate tends to grow under load. From which point(s) can it continue propagating if only one end is treated? • Consider what drilling a smooth, round hole does to the sharp tip of a crack. How does this change the way stress is distributed at that location? • Ask yourself whether the crack should terminate exactly at the hole edge or be contained fully within the drilled area.

✅ Before You Answer

• Verify whether standard practice is to relieve stress at one end or both ends of a crack before welding. • Check whether a smooth drilled hole is intended to fully surround the crack tip or just meet it. • Confirm the typical size and placement of an emergency crack-arrest hole used in shipboard steel repairs.