Material Testing Machine
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Material testing machine
General information
Materials testing machines, synonymously also referred to as universal testing machines (UTM), also known as tensile testing machines and simplified universal tester or testing machines, are used to determine physical (mechanical) material properties in materials testing, plastics testing and plastics diagnostics.
In addition to determining material properties, materials testing machines are also used in component testing for quality assurance of components, assemblies or for functional testing of complex designs through to finished product testing, e.g. in the automotive industry.
The two main measured variables here are the force and the change in length under the effect of the load.
Realisable test methods
The main material testing methods realised, which are explained in the WIKI-Lexicon Polymer Testing and Diagnostics, are
The most frequently performed material testing method, regardless of the material group, is the tensile test, whereby the stress–strain diagram and the characteristic material values determined from it are at the centre of consideration.
Design of a materials testing machine
The materials testing machine generally consists of a load frame whose rigidity is adapted to the testing task, a fixed traverse and a moving transverse beam, which is moved by the drive of the electromechanical materials testing machine by means of one, two or more spindles. The fixed traverse is also known as the crosshead.
The crosshead is moved in one direction at a predetermined test speed in order to load the respective test specimen, which has been fixed between the transverse and the crosshead with a test specimen clamp.
Force and length measurement
For force measurement in materials testing machines, mainly
- electromechanical force transducers or load cells and
- piezoelectric load cells
are used. Depending on the test task and load type, different length measurement techniques are used to record the extension, whereby the simplest metrological case is the recording of the incremental traverse path:
- clip-on Gauges
- differential length measuring system ( strain gauge)
- optical displacement measurement techniques (laser, laser speckle and video extensometers)
Drives and automation
The drives for a materials testing machine are divided into
- electromechanical drive,
- servo-hydraulical drive and
- hybrid drives, which are mostly used in high-speed testing.
An overview of the manufacturers of materials testing machines shows the large number of competent partners for static and dynamic materials testing and plastics testing, whereby in addition to materials testing machines for the classic testing methods (tensile, compression and flexure testing), numerous special testing machines are also manufactured for specific requirements. Increasingly, automated testing systems are being used in the central laboratories of larger plastics manufacturing companies, which operate several universal testing machines using robots.
See also
- Machine compliance
- Crosshead speed
- Test speed
- Velocity
- Measuring accuracy
- Tensile test
- Compression test
References
- Dripke, M., Michalzik, G., Bloching, H., Fahrenholz, H.: Mechanische Prüfverfahren und Kenngrößen – kompakt und verständlich, Band 1: Der Zugversuch bei quasistatischer Beanspruchung. Castell, Wuppertal (2002) (ISBN 3-934255-50-7; see AMK-Library under C 14)
- DIN 51220 (2022-10): Materials Testing Machine – General Requirements, Calibration and Verification of Materials Testing Machine
- ISO 6892-1 (2019-11): Metallic Materials – Tensile Test – Part 1: Method of Test at Room Temperature
- ISO 7500-1 (2018-02): Metallic Materials – Calibration and Verification of Static Uniaxial Testing Machine – Part 1: Tension/Compression Testing Machines – Calibration and Verification of the Force-Measuring System
- ISO 5893 (2019-07): Rubber and Plastics Test Equipment – Tensile, Flexural and Compression Types (Constant Rate of Traverse) – Specification (AMD 1: 2020-09; Amendment 1)
Weblinks
Wikipedia – The Free Encyclopedia: Materials Testing Machine: https://en.wikipedia.org/wiki/Universal_testing_machine