Why is stress concentration in ductile materials less harmful than in brittle materials?

• A. In ductile material local yielding may distribute stress concentration
• B. Ductile materials have larger Young's modulus
• C. Poisson's ratio is larger in ductile materials
• D. Modulus of rigidity is larger in ductile materials

Answer: (A)

Stress concentration refers to the location in a material where stress is concentrated—often at geometric discontinuities like notches, holes, or cracks. In ductile materials, which are characterized by their ability to deform plastically before failure, local yielding occurs at points of high stress concentration. This means that the material can undergo some degree of permanent deformation, allowing it to redistribute the applied load over surrounding areas.

As a result, the presence of a stress concentrator in a ductile material may lead to local yielding, which can alleviate the concentration of stress and prevent catastrophic failure. This capacity for redistribution means that ductile materials can absorb energy and continue to function despite local flaws, providing a more forgiving response under stress.

In contrast, brittle materials tend to fail suddenly and without warning when subjected to stress concentrations, as they have little capacity for plastic deformation. Therefore, the ability of ductile materials to handle stress concentrations through yielding directly explains why they are generally less harmful in the context of applied stresses compared to brittle materials.