Engineering stress is defined as the force divided by what area?

• A. Force over current area
• B. Force divided by original cross-sectional area
• C. Strain times modulus
• D. Force over final area

Answer: (B)

Engineering stress is a measure of the internal force per unit area using the original cross-sectional area before loading. This keeps the stress value tied to the material’s initial geometry, so comparisons between materials don’t change as the specimen deforms or necks during testing. That’s why the correct form is force divided by the original cross-sectional area.

Using the current or final area would give the true stress, which accounts for the instantaneous area as deformation progresses—this value increases when the cross-section shrinks, especially during necking. The option that corresponds to strain times modulus relates to Hooke’s law in the linear elastic region (sigma = E * epsilon), not to the definition of engineering stress itself. The option using the final area is effectively the same idea as the true stress approach, which isn’t what engineering stress uses by definition.