What occurs when stress is concentrated at a material's surface irregularity?

When stress is concentrated at a material's surface irregularity, it leads to localized stress within that area, which can exceed the material's yield strength. This often results in the initiation of a crack. Surface irregularities such as scratches, notches, or any form of discontinuity can act as stress risers, causing the material to respond differently than it would under uniform stress distribution.

As stress concentrates around the irregularity, microscopic or macroscopic flaws may begin to propagate due to the high localized stress. This process is known as crack initiation, which is a critical step in the failure of materials under load. If the stress continues to exceed the material’s capacity to withstand it, the crack can grow, leading to eventual failure of the component.

In contrast, simply enduring stress without any changes occurring is inaccurate, as surface irregularities inherently influence how stress is distributed within the material. Temporary deformation does not necessarily lead to a crack formation; it may only involve elastic or plastic deformation without fracture. The material becoming brittle could be a consideration in terms of its overall behavior under stress but does not specifically address the immediate consequence of concentrated stress at a surface irregularity. Thus, the correct outcome of concentrated stress in this context is the initiation of a crack.