The lowdown on tensile testing microfibres

The tensile test, sometimes called the tension test, is the most basic kind of mechanical test that can be carried out on a material. Quick, simple and easy to standardise, tensile tests are widely used in industry and architectural design to test the suitability of certain materials for specific applications.

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The test involves no more than using a controlled environment to pull on something and see how it reacts to the forces being applied. The test reveals how much the material will elongate and how strong it is. The point at which the material eventually fails is often called the ‘ultimate strength’ point when the material’s tensile strength is being charted.

Using tools to deal with small samples

If very small samples – such as microfibres – need to be tested for tensile strength, it is often preferable to use a proprietary toolset. In sample preparation, the smallness of the sample offers particular challenges. Micro grippers are sometimes used to allow the microfibres to be handled without compromising their structure.

Firstly, one fibre is taken from a large bundle in the microfibre material. One end is dipped into a single drop of glue that can be cured in UV light. The fibre is then attached to the edge of a glass slide. A sensing probe is attached to the other side of the microfibre sample and it is now ready for tensile testing.

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Uses of microfibre tensile tests

These tests are used to describe the mechanical characteristics of silica microfibres, for example, that have been developed through the technique of roller electrospinning. If fibres will eventually be used in a tensile structure, these tests are vital in establishing how strong the fibres are and how much they can be pulled or stretched before failing. It is probably becoming obvious that this is an area in which specialised knowledge of tensile structures, their strength and their use in architectural applications by companies such as, is key.

Initially, the fibre is in what might be described as a relaxed state. It is stretched out straight, then stretched some more. The tests examine the distance it stretched, its stiffness. and its strength when stretched.

A cycle of tests will be used to measure the way the fibre reacts to several iterations of loading and unloading.