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Typical lectromechanical Universal Testing Machine Test fixture for three point flex test. A universal testing machine (UTM), also known as a universal tester, [1] 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 ...
Tensile testing, also known as tension testing, [1] is a fundamental materials science and engineering test in which a sample is subjected to a controlled tension until failure. Properties that are directly measured via a tensile test are ultimate tensile strength , breaking strength , maximum elongation and reduction in area. [ 2 ]
The ultimate tensile strength of a material is an intensive property; therefore its value does not depend on the size of the test specimen.However, depending on the material, it may be dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material.
The punch is then pushed with a constant displacement rate through the specimen. A flat punch or concave tip pushing a ball are typically used in the test. [24] After the testing, some characteristic parameters such as force-displacement curves are used to estimate yield strength, ultimate tensile stress.
The test method for conducting the test usually involves a specified test fixture on a universal testing machine. Details of the test preparation, conditioning, and conduct affect the test results. The sample is placed on two supporting pins a set distance apart. Calculation of the flexural stress
The ultimate strength is the maximum stress that a material can withstand before it breaks or weakens. [12] For example, the ultimate tensile strength (UTS) of AISI 1018 Steel is 440 MPa. In Imperial units, the unit of stress is given as lbf/in 2 or pounds-force per square inch. This unit is often abbreviated as psi.
In some applications the video extensometer is replacing mechanical measurement units - but this is mainly clip-on devices. When measuring the modulus of elasticity on 50 mm gauge length plastics to ISO 527 an accuracy of 1 μm is required. Some video extensometers cannot achieve this, whilst for production testing it is better to use automated ...
For green strength testing, the fixture can be removed, at the appropriate time, and the specimen can be loaded in shear until it finally fails. This will verify the green strength of the material. [1] Other testing, such as cleavage loading and peel test, can be used to determine both the green strength and final strength of a material.