Alongside tensile and flexion tests, one of the important and basic mechanical tests is compression testing. In this test, the behaviour of the material under an applied crushing load is determined. In this test, compressive pressure is applied to the specimen using universal compression testing machines. In this testing, the properties of the material are assessed, and a stress-strain diagram is made to evaluate the qualities like yield point, elastic limit and compressive strength.
Why is the compression test conducted?
The following are the reasons why the compression test is conducted.
- It is performed when the manufacturers want to assess the safety of the component, material and products during different manufacturing stages.
- It is often performed on brittle materials like concrete, metals and composites as their safety and integrity play a crucial role under the act of compressive forces when used as load-bearing capacities.
- Compression testing is performed on the finished products, unlike tensile testing, which is performed on a specific material.
Engineers can tune a fine balance between the strength of the product and material conservation using compression testing.
How Compression testing equipments work?
A compression testing machine is usually made with concrete specimens up to 20 cm in diameter and 30 cm in height. In compression testing, the testing equipment applies compressive load and force to the test specimen until it squishes or breaks.
Ultimate Compressive strength
The value of compressive strength where the material completely fails is the ultimate compressive strength of the materials. When brittle materials are crushed, and they reach the ultimate compressive strength, their load drastically drops. The materials which have high ductility continue to deform until the load is not applied.
The specific deformations of compressive strength can be 1%, 5% and 10% of the original height of the test’s specimen.
Industry-specific testing standards
There are various ISO and ASTM standards related to the compression testing of various materials. In case of Compression testing of 2-inch concrete cubes, it is ASTM C109, and Moisture test compacted soil, it is ASTM D2844. There are various other standards too which vary according to the testing specimen.
Compression testing equipments used for compression tests are hand-operated equipments. The manufacturers also offer a wide variety of computerized compression testing machines.
So, in order to measure the compressive and elastic properties of low ductility materials and brittle materials, compression tests are necessary. These tests can also be used to determine the compressive yield point, proportional limit, modulus of elasticity and compressive strength. These mentioned properties are really crucial to determine because, based on these properties, we can judge if it is fit for a specific application. The materials having high exhibit tensile strength will have low compressive strength and materials having high compressive strength will have low tensile strength. It is similar to tensile testing, but it is performed on the finished products. This article is an attempt to explain the compression testing, why it is conducted and how it performs.