Laboratory Services

Pure shear strain state

Pure shear test is a longitudinal elongation where width of the specimen is at least 10 times larger than height. Due to nearly incompressible behaviour of elastomer, a pure shear state exist in the specimen at 45 degrées to the stretching direction of such specimen.

Volumetric compression

Volumetric compression testing evaluates compressibility of materials. A specimen is compressed inside a confined cavity and cannot expand laterally. The small displacement is thus a direct measure of compressibility, given the stiffness of the instruments is greater. The initial slope of the resulting strain-stress is the bulk modulus of the material.

Simple compression strain state

Simple compression is an easy way to evaluation elastomer behaviour when subject to compression strain. This being said, it is difficult to eliminate friction between elastomer and testing tooling, thus impossible to permit free lateral expansion of specimen. Since actual friction cannot be precisely measured, data correction cannot be applied and testing results must be used with great care.

Equi-biaxial strain state

For nearly incompressible materials, it is possible to create a pure compression state through tension. Radial stretching of circular discs made of materials with Poisson's coefficient near 0.5 results in pure compression strain state at center of specimens. This experiment is more complex than a simple compression test but gives more accurate compression models.

Simple tentions strain state

The objective of this test is to create pure tension without any lateral constraint during longitudinal elongation of the specimen. In order to attain this state, the specimen needs to be at least 10 times longer than its width or thickness.

Stress relaxation

Stress relaxation testing consist in stretching and holding a uni-axial specimen to a given strain and measuring the stress decay over time. This stress decaying is associated to viscoelastic properties of materials.