In addition to the climatic tests that are commonly faced, many materials must undergo mechanical tests to verify their resistance before being released to the market.
Laboratory instruments that perform this type of testing are called universal testing machines and there are several types.
In the following article we will see what are the different types of universal testing machines, what type of tests they perform and why they cannot be separated from the climatic chambers.
What Is a Universal Testing Machine?
The UTM Machine is a laboratory instrument capable of impressing forces of different types and intensities on materials. It is defined as universal due to the wide range of possible uses, but in the past it was more simply known as a “traction machine” or “dynamometer”.
As we will see, the structure of these machines can vary but generally includes a chassis which may be composed of one or two support columns.
What to Check When Investing in Universal Testing Machines?
Materials passing through the universal testing machine must undergo two major categories of testing: the compressive strength test and the ultimate tensile strength test.
The compressive strength test is generally carried out in the monoaxial regime and verifies the resistance of materials to loads which tend to deform them and reduce their extension, or to compress them.
It happens to be mainly used on concrete and is regulated by this international standard.
The ultimate tensile strength test, on the other hand, identifies the limit, in terms of applied external force or stress, beyond which the material is definitively useless from a strength point of view.
A Universal Tensile Testing Machine Subjects a Sample to a Tensile Force Until Failure.
This test makes it possible to obtain data such as breaking strength, fatigue strength, yield strength, yield stress, Young’s modulus. The emphasis is often placed on the breaking strength but sometimes the elongation at breaking or at a given load is the information sought.
The tested samples are made of any material. It can therefore be elastomer, plastic, steel, leather, wood fabric and many others. The sample or product to be tested is placed in the testing machine with the help of gripping accessories such as jaws.
The Working Area of Universal Testing Machines
One of the Best Universal Testing Machines offers an advantage over two-column machines: accessibility from three sides. They are, however, limited by the swan neck which corresponds to accessibility on the transom side.
Twin-column machines are limited on both sides where the crosshead drive screws are located. These data must therefore be taken into account when choosing the machine. The vertical space taken up by jaws and other gripping accessories should not be neglected. The working area on electromechanical testing machines is usually between the moving crosshead and the bottom support. On some models the work area is shared between the two levels. Compression on one side of the crosspiece and tension on the other. This configuration is also very common on hydraulic machines. Finally, on even more advanced machines we can carry out tests in both directions up and down.