singularity at crack tip

The singularity at a crack tip refers to a point where the stress (force per area) becomes extremely high as the crack extends through a material. Imagine stretching a plastic ruler until it breaks; near the crack tip, the material experiences intense stress that concentrates there. This concentration causes the stress to theoretically approach infinity, meaning conventional formulas don't work well at that point. Understanding this helps engineers predict when and how materials might fail, and develop stronger, more resilient structures by analyzing the behavior around these critical regions.