Question

Which one of the following is the definition of ultimate tensile strength (UTS) obtained from a stress-strain test on a metal specimen?

• A. Stress value where the stress-strain curve transitions from elastic to plastic behavior
• B. The maximum load attained divided by the original cross-sectional area
• C. The maximum load attained divided by the corresponding instantaneous cross-sectional area
• D. Stress where the specimen fractures

Hint:

UTS is always based on the original cross-sectional area, while true stress uses the instantaneous area. Remember this difference to avoid confusion in strength calculations.

Answer 1

The Correct Option is B

Ultimate Tensile Strength (UTS) is a fundamental mechanical property obtained from a tensile test on a metallic specimen. It represents the highest stress a material can withstand before necking initiates.
Step 1: Understanding UTS.
During a tensile test, the load on the specimen increases until it reaches a maximum value. This peak load corresponds to the highest engineering stress achieved before instability begins.
Step 2: Definition Based on Engineering Stress.
Engineering stress is defined using the original cross-sectional area of the specimen. Therefore, UTS is calculated as:
\[ \text{UTS} = \frac{\text{Maximum Load}}{\text{Original Cross-sectional Area}} \]
Step 3: Eliminating Incorrect Options.
Option (A) describes the yield point, not UTS.
Option (C) uses instantaneous area, which corresponds to true stress, not engineering UTS.
Option (D) refers to fracture stress, which occurs after UTS.
Thus, the correct definition of UTS is given in Option (B).
Final Answer: (B) The maximum load attained divided by the original cross-sectional area