Poisson's Ratio ASTM D638, ISO 527

When uniaxial force is applied, the specimen will deform not only in the direction of the force (axial) but also laterally (transverse). Poisson’s Ratio is a measure of transverse strain against axial strain when uniaxial stress is applied.

Test Procedure:
The specimen is clamped into the grips of the Instron universal tester. Two strain measuring devices are attached to the specimen, one axial and one transverse. A uniaxial force is applied at a predetermined speed.

Specimen size:
A standard tensile bar is typically used.

A stress-strain graph is produced and Poisson’s ratio is calculated. 

**Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. Standards can be obtained from appropriate standard authorities. 


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