ASTM E132 Test Method for Poisson’s Ratio at Room Temperature

In ASTM E132 test method, uniaxial force is applied to a solid. It deforms in the direction of the applied force, but also expands or contracts laterally depending on whether the force is tensile or compressive. If the solid is homogeneous and isotropic, and the material remains elastic under the action of the applied force, the lateral strain bears a constant relationship to the axial strain. This constant, called Poisson's ratio, is an intrinsic material property just like Young's modulus and Shear modulus. In this test method, the value of Poisson's ratio is obtained from strains resulting from uniaxial stress only.

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ASTM E132 Test Method for Poisson’s Ratio at Room Temperature

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Overview
Scope, Applications, and Benefits
Test Process
Specifications
Instrumentation
Results and Deliverables

Overview

The ASTM E132 standard provides a standardized method of determining Poisson’s ratio in structural materials by conducting a uniaxial tension test at room temperatures.

Poisson’s ratio is the ratio of sideways strain to the strain in the direction of stretching of the material when it is subjected to tension.This test is applicable for testing rectangular-sectioned materials and those that strain immediately upon loading.

Scope, Applications, and Benefits

Scope

ASTM E132 is applicable to structural metallic materials, structural polymeric materials, and other rigid materials tested in tension using rectangular cross-section specimens. The standard uses the measurement of longitudinal and transverse strains during tension testing at room temperature, which helps obtain an accurate value of Poisson’s ratio.

It is applicable to:

Structural metallic materials
Structural polymeric materials
Rigid materials tested in tension
Rectangular cross-section specimens

It helps determine:

Poisson’s ratio by simultaneous measurement of longitudinal and transverse strains during tension testing

Applications

Mechanical property evaluation
Structural design calculations
Finite element analysis (FEA) input data
Quality control of structural materials
Research and development
Elastic behaviour characterization
Engineering material selection

Benefits

Provides accurate Poisson’s ratio at room temperature
Simultaneous longitudinal and transverse strain measurement
Applicable to ductile and brittle materials
Supports structural and mechanical design
Standardized and repeatable methodology
Improves reliability of elastic property data
Essential for stress–strain modelling

Test Process

Specimen Preparation and Setup

Measure width and thickness to determine cross-sectional area, mount the specimen in tensile grips, and attach extensometers to the gauge section.

Controlled Loading

Apply tensile load at a low, controlled speed to prevent thermal effects.

Strain Measurement and Data Recording

Record longitudinal and transverse strains simultaneously and obtain multiple strain data pairs.

Analysis and Test Completion

Plot strain versus load data; continue testing to yield (ductile) or until failure (brittle).

Technical Specifications

Parameter	Details
Test Temperature	Room temperature
Specimen Type	Rectangular cross-section
Width Parallelism Tolerance	Within 0.001 in. (0.025 mm)
Thickness Parallelism Tolerance	Within 0.0001 in. (0.0025 mm)
Width Measurement Accuracy	Within 0.0001 in. (0.0025 mm)
Thickness Measurement Accuracy	Within 0.001 in. (0.025 mm)
Measured Parameters	Longitudinal strain (εl), Transverse strain (εt)

Instrumentation Used for Testing

Universal testing machine (UTM)
Deflectometer
Optical extensometer or transverse extensometer
Precision micrometer or calliper
Data acquisition system
Strain measurement software

Results and Deliverables

Poisson’s ratio value at room temperature
Longitudinal and transverse strain data
Stress–strain curve
Strain vs. load graph
Yield strength data (if applicable)
Elastic property evaluation report
Compliance reports

Frequently Asked Questions

The procedure for calculating Poisson’s Ratio (ν), or the ratio of transverse to axial strain, is defined by ASTM E132. Poisson’s Ratio is a critical value used in the calculation of the shear modulus and in structural analysis. It is used to predict the deformation of materials when subjected to multi-axial loading.

The values of transverse strain are very small and require high sensitivity for measurement. ASTM E132 testing employs biaxial extensometers or bonded strain gauges to measure the strain values simultaneously. This reduces the chances of errors due to bending or misalignment of the specimens.

ASTM E132 is mainly applicable to structural metals like aluminum, steel, and titanium alloys. It is also applicable to rigid polymers and quasi-isotropic composites. The materials should have stable elastic properties.

The specimen should be rectangular or dogbone-shaped. A high width-to-thickness ratio ensures that the stresses are evenly distributed. The gauge length should be long enough to ensure that the strain measurement is stabilized. This geometry helps to reduce the scatter in the results of Poisson’s Ratio.

Measurement accuracy depends on precise strain sensing, proper specimen alignment, stable loading within the elastic range, and minimizing bending effects. Small errors in transverse strain measurement can significantly affect calculated Poisson’s Ratio values.