In mechanics, compressive strength is the capacity of a material or structure to withstand loads tending to reduce size. In other words, compressive strength resists compression, whereas tensile strength resists tension. In the study of strength of materials, tensile strength, compressive strength, and shear strength can be analyzed independently.
Measuring the compressive strength of a steel drum
A cylinder being crushed under a UTM
Figure 1: microcrack nucleation and propagation
A secondary crack growing from the tip of a preexisting crack
Ultimate tensile strength
Ultimate tensile strength is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials, the ultimate tensile strength is close to the yield point, whereas in ductile materials, the ultimate tensile strength can be higher.
Two vises apply tension to a specimen by pulling at it, stretching the specimen until it fractures. The maximum stress it withstands before fracturing is its ultimate tensile strength.
Round bar specimen after tensile stress testing
The "cup" side of the "cup–cone" characteristic failure pattern
Some parts showing the "cup" shape and some showing the "cone" shape
