A universal testing machine, also known as a universal tester, materials testing machine or materials test frame, is used to test

Physical test

A physical test is a qualitative or quantitative procedure that consists of determination of one or more characteristics of a given product, process or service according to a specified procedure...

 the tensile stress and compressive strength

Compressive strength

Compressive strength is the capacity of a material or structure to withstand axially directed pushing forces. When the limit of compressive strength is reached, materials are crushed. Concrete can be made to have high compressive strength, e.g...

 of materials. It is named after the fact that it can perform many standard tensile and compression tests on materials, components, and structures.

Components

• Load frame - usually consisting of two strong supports for the machine. Some small machines have a single support.
• Load cell
  Load cell
  A load cell is a transducer that is used to convert a force into electrical signal. This conversion is indirect and happens in two stages. Through a mechanical arrangement, the force being sensed deforms a strain gauge. The strain gauge measures the deformation as an electrical signal, because the...
  
   - A force
  Force
  In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
  
   transducer
  Transducer
  A transducer is a device that converts one type of energy to another. Energy types include electrical, mechanical, electromagnetic , chemical, acoustic or thermal energy. While the term transducer commonly implies the use of a sensor/detector, any device which converts energy can be considered a...
  
   or other means of measuring the load is required. Periodic calibration
  Calibration
  Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....
  
   is usually called for.
• Cross head - A movable cross head (crosshead) is controlled to move up or down. Usually this is at a constant speed: sometimes called a constant rate of extension (CRE) machine. Some machines can program the crosshead speed or conduct cyclical testing, testing at constant force, testing at constant deformation, etc. Electromechanical, servo-hydraulic, linear drive, and resonance drive are used.
• Means of measuring extension - Many tests require a measure of the response of the test specimen
  Specimen
  A specimen is a portion/quantity of material for use in testing, examination, or study.BiologyA laboratory specimen is an individual animal, part of an animal, a plant, part of a plant, or a microorganism, used as a representative to study the properties of the whole population of that species or...
  
   to the movement of the cross head. Extensometer
  Extensometer
  An extensometer is a device that is used to measure small/big changes in the length of an object. It is useful for stress-strain measurements and tensile tests. Its name comes from "extension-meter". It was invented by Dr. Charles Huston who described it in an article in the Journal of the...
  
  s are sometimes used.
• Output device - A means of providing the test result is needed. Some older machines have dial or digital displays and chart recorder
  Chart recorder
  A chart recorder is an electromechanical device that records an electrical or mechanical input trend onto a piece of paper . Chart recorders may record several inputs using different color pens and may record onto strip charts or circular charts...
  
  s. Many newer machines have a computer interface for analysis and printing.
• Conditioning - Many tests require controlled conditioning (temperature, humidity, pressure, etc.). The machine can be in a controlled room or a special environmental chamber
  Environmental chamber
  An environmental chamber is an enclosure used to test the effects of specified environmental conditions on biological items, industrial products, materials, and electronic devices and components. Environmental chambers help evaluate product quality and reliability, and identify manufacturing flaws...
  
   can be placed around the test specimen for the test.
• Test fixture
  Test fixture
  A test fixture is something used to consistently test some item, device, or piece of software.-Electronics:Circuit boards, electronic components, and chips are held in place and subjected to controlled electronic test signals. One example is a bed of nails tester.-Software:Test fixture refers to...
  
  s, specimen holding jaws, and related sample making equipment are called for in many test method
  Test method
  A test method is a definitive procedure that produces a test result.A test can be considered as technical operation that consists of determination of one or more characteristics of a given product, process or service according to a specified procedure. Often a test is part of an experiment.The test...
  
  s.

Use

The set-up and usage are detailed in a test method

Test method

A test method is a definitive procedure that produces a test result.A test can be considered as technical operation that consists of determination of one or more characteristics of a given product, process or service according to a specified procedure. Often a test is part of an experiment.The test...

, often published by a standards organization

Standards organization

A standards organization, standards body, standards developing organization , or standards setting organization is any organization whose primary activities are developing, coordinating, promulgating, revising, amending, reissuing, interpreting, or otherwise producing technical standards that are...

. 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 capacity.

Standards

• ASTM E4 - Practices for Force Verification of Testing Machines
• ASTM E74 - Practice for Calibration of Force Measuring Instruments for Verifying the Force Indication of Testing Machines
• ASTM E83 - Practice for Verification and Classification on Extensometer Systems
• ASTM E1012 - Practice for Verification of Test Frame and Specimen Alignment Under Tensile and Compressive Axial Force Application
• ASTM E1856 - Standard Guide for Evaluating Computerized Data Acquisition Systems Used to Acquire Data from Universal Testing Machines
• JIS K7171 - Standard for detrmine the flextural strength for plastic material & products
• Many other standard tests for specific materials and products. These usually call for the details of machine set-up, fixturing, and testing.