Tensile Strength TestingFor manufactured products or assemblies, tensile or tension testing is the application of uniaxial force to measure the performance of a test sample, up to the point of yield or breaking, whether sharp or gradual. In simple terms, it is pulling something apart in a straight line and seeing how it changes. Even where performance to ultimate failure is not required, characteristics of elongation, deformation and relaxation can be accurately recorded, as in elastomers and springs. The sample under test may be a material sample, or a manufactured product.
Tensile testing is an important part of design as well as quality control, for ensuring product safety and integrity, and is an essential part of testing consistency in manufacture and construction.
Tensile tests are used to measure the strength of textiles and stitching, couplings and connectors, joints and crimp fastenings, industrial fixings and fasteners, or to measure the effort required to open a drawer or door, or in the packaging industry to measure the force required to open a container, flip a cap, pull a stopper, etc. Many have a complementary compressive test (push and pull, open and close) where both are required of a product, and here a universal test stand or gauge fulfils both requirements. Since the shapes and features of manufactured products are so variable, and can be awkward to grip without deformation, Mecmesin frequently designs custom fixtures to suit users’ individual products.
For materials testing, what is usually required is to measure the full tensile properties rather than the ultimate strength of a material, such as an elastic modulus. Here the test standards define the sample dimensions, and standard grips and fixtures are used.
Key features of tensile testing include accurately controlled speed, extension and force, the ability to hold at extension and load, and the use of appropriate grips and fixtures. Tensile tests need to be representative of the sample as it is used, especially if it is a product rather than a materials test. The Mecmesin range of tensile testers includes models with extended columns suitable for highly elastic tests.
Tensile test results can provide a detailed profile of force, extension and time, including partial failure, slippage, and sharp and percentage break. For materials testing, the data curve of force vs extension is largely used to determine the elastic limit and ultimate tensile strength.
A very wide range of tensile testing standards have been developed by organisation such as ASTM, BSI, DIN, ISO and MIL. Commonly used test standards include:
Standards relating to specific test groups such as pull, peel (including adhesives), tear (including fibres and textiles), and shear, are listed on those pages.
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