Which statement best describes ultimate tensile strength (UTS) on a stress-strain curve?

• A. It is the maximum load before fracture
• B. It is the first yield point
• C. The maximum stress coordinate value on the curve
• D. The minimum cross-sectional area

Answer: (C)

Ultimate tensile strength is the highest engineering stress the material reaches during a tensile test, and it appears as the peak on the stress-strain curve. Engineering stress is defined as sigma = F/A0, using the original cross-sectional area, so UTS marks the maximum force per the initial area that the material can sustain before necking begins. After reaching this peak, necking reduces the area and the engineering stress drops, even though the true stress in the neck may continue to rise. This makes UTS specifically the maximum stress value along the curve, not the first yield point, not the cross-sectional area itself, and not simply the maximum load before fracture.