A universal testing machine (UTM), also known as a universal tester, universal tensile machine, materials testing machine, materials test frame, is used to test the tensile strength (pulling) and compressive strength (pushing), flexural strength, bending, shear, hardness, and torsion testing, providing valuable data for designing and ensuring the quality of materials. An earlier name for a tensile testing machine is a tensometer. The "universal" part of the name reflects that it can perform many standard tests application on materials, components, and structures (in other words, that it is versatile).
An electromechanical UTM utilizes an electric motor to apply a controlled force, while a hydraulic UTM uses hydraulic systems for force application. Electromechanical UTMs are favored for their precision, speed, and ease of use, making them suitable for a wide range of applications, including tensile, compression, and flexural testing.
On the other hand, hydraulic UTMs are capable of generating higher forces and are often used for testing high-strength materials such as metals and alloys, where extreme force applications are required. Both types of UTMs play critical roles in various industries including aerospace, automotive, construction, and materials science, enabling engineers and researchers to accurately assess the mechanical properties of materials for design, quality control, and research purposes.
Several variations are in use. Common components include:
The set-up and usage are detailed in a test method, often published by a standards organization. This specifies the sample preparation, fixturing, gauge length (the length which is under study or observation), analysis, etc.
The specimen is placed in the machine between the grips and an extensometer if required can automatically record the change in gauge length during the test. If an extensometer is not fitted, the machine itself can record the displacement between its cross heads on which the specimen is held. However, this method not only records the change in length of the specimen but also all other extending / elastic components of the testing machine and its drive systems including any slipping of the specimen in the grips. Once the machine is started it begins to apply an increasing load on specimen. Throughout the tests the control system and its associated software record the load and extension or compression of the specimen.
Machines range from very small table top systems to ones with over 53 MN (12 million lbf) capacity.[1]