Stress concentration: primary cause in machine members Identify the dominant cause that creates localized high stresses relative to nominal stress. Choose the correct option.

Concept
Stress concentration arises primarily from geometric discontinuities such as holes, notches, grooves, fillet corners, and sudden changes in section. These features raise local stresses above the nominal average.

Why others are not primary causes
Load or property variations affect overall stress but do not, by themselves, create the localized peaks that define stress concentration.

Final Answer
Abrupt change of cross-section (geometric discontinuity)