Question

In a compression test, a ductile material specimen typically exhibits:

• A. Necking and fracture is observed
• B. Brittle fracture occur
• C. Significant elongation takes place
• D. Significant shortening and bulging take place

Hint:

In compression testing of ductile materials, look for shortening and bulging — not necking or elongation, which are features of tensile tests.

Answer 1

The Correct Option is D

In a compression test, a ductile material is subjected to a compressive load. Unlike in tensile testing, ductile materials do not undergo necking or fracture early under compression. Instead, they display a distinct behavior characterized by:
- Shortening of the specimen along the axis of the applied load, and
- Bulging or barreling perpendicular to the load due to Poisson’s effect.
This plastic deformation continues without fracture for a long time because ductile materials can accommodate compressive strains through dislocation motion.
On the other hand:
- Necking is typical in tensile tests, not compression.
- Brittle fracture is associated with brittle materials.
- Elongation occurs under tensile, not compressive, loading.
Thus, the correct behavior in compression for ductile materials is significant shortening and bulging.