Tension vs Compression

Compressive tests require higher capacity machines due to higher compressive strengths compared to tensile strengths.

In the case of general materials, the specimen goes under permanent deformation beyond its elastic limit while under tension. This leads to the creation of voids within the atomic/molecular structure of the material and eventually development of stress concentration around these voids. Further increase in tensile load leads to easier deformation of the specimen (beyond yield point) and thus lead to failure.

When the same specimen is subjected to compression, these voids gets smaller and smaller leading to even higher loads being required to deform or crush the specimen.