How does a tensiometer work?

for measuring strain to failure on semi rigid or elastomaterials

A tensometer works with the principle of an expansive force being applied to the sample locked in the machine (tensometer). It offers integral values of force to be applied to the sample for eg by the modification of the pressure/unit area of a liquid such as mercury. It contains a medium for measurement of the extension produced (eg a drum plotter). The results of which can be used to calculate the stress, strain and hence the modulus of elasticity. it can also be used to determine the degree of a mechanical property of a material, eg the yield strength, ultimate tensile strength etc.