Universal testing machine
The universal, also called test machine, it is used to determine the stress-strain diagrams for materials and characteristics. Specifically, tensile, or bending tests compression tests can be performed using tensile tests are most common.
Tensile testing machines are special testing machines, which are suitable to represent one-dimensional motion sequences in a force -displacement diagram or in a stress-strain diagram.
The classic application is the crucial test in which a sample is subjected to an increasing tensile load for so long until she finally rips. The force-displacement diagram generated during this experiment provides information about the strength, elasticity and plastic deformation of the material sample.
Construction
The tensile testing machine is generally composed of a fixed and a moving cross-member, which is driven electrically or hydraulically by means of one or two spindles.
The Traverse is a defined speed moves (depending on the inspection specification ) in a direction to tear the test-piece is held by the sample holder between the trusses. The deformation of the sample on the crosshead or a strain sensor (also called the extensometer ) and recording the force required with a force transducer. With the help of the sample dimensions, the stresses and strains can be calculated therefrom. The safe and precise measurement of elongation when testing highly extensible, highly elastic and touch-sensitive samples is thereby advantageously carried out on non-contact optical measurement systems. To measure the forces 7500-1 load cells are preferred according to accuracy classes according to ISO with very large ranges.
Increasing importance have in addition to these static materials testing machines also
- Automated inspection systems, and
- Testing for dynamic and fatigue testing and
- Systems for testing under temperature and climate influences.
Requirements
According to the requirements of universal testing machines are inexpensive, single-column table models with 3 kN double spindle models with 50 kN to large hydraulic load machines from 300 - 2000 kN offered.
The requirements for tensile testing machines are, inter alia, defined under the following standards:
Standardize
- DIN 51220 for General Requirements for material testing and for verification and calibration
- DIN EN ISO 6892-1: Metallic materials - Tensile testing - Part 1 (formerly EN 10002 )
- EN ISO 7500-1 Metallic materials - Verification of static uniaxial testing machines - Part 1: train and compression testing machines - Verification and calibration
- ISO 5893 testing equipment for rubber and plastics