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

What is ASTM E132?

ASTM E132 test method covers the determination of Poisson’s ratio from tension tests of structural materials at room temperature. This test method is limited to specimens of rectangular sections and materials in which strain is produced immediately during the test.

ASTM E132 Sample Preparation Guide

In ASTM E132 (Standard Test Method for Poisson’s Ratio at Room Temperature), the specimen width and thickness shall be parallel within 0.001 in. (0.025 mm) and 0.0001 in. (0.0025 mm), respectively. Specimen thickness shall be measured to within 0.001 in. (0.025 mm), and width is measured to within 0.0001 in. (0.0025 mm) at three locations, and an average is determined.

What are the Testing Procedure and Requirements of ASTM E132?

In ASTM E132, the width and thickness of the sample are measured and recorded.  The average cross-sectional area of the specimen gauge section is calculated. The specimen is placed in the grip. The deflectometer and the optical extensometer are attached to the gauge section of the sample. The two measurement devices are placed on the specimen with a free distance of at least one specimen width between any extensometer and the nearest fillet, and at least two specimen widths between any extensometer and the nearest grip. The load is applied. The testing speed is low enough to make the thermal effects of adiabatic expansion or contraction negligible. 

The precision of the value of Poisson’s ratio obtained in the ASTM E132 test depends on the number of data pairs of longitudinal and transverse strain taken. For ductile materials, the test is continued until the yield strength or yield point, and sometimes the strength at a strain greater than the yield strain is determined. For brittle materials, the extensometer is removed, and the test is continued until failure. The graph is plotted for the average longitudinal strain and the average transverse strain against the applied force.

Analysis Result and Interpretation

• ASTM E132 test method covers the determination of Poisson’s ratio from tension tests of structural materials at room temperature.
• The formula for Poisson’s ratio is,

 =ϵtϵl

ϵt is the Lateral or Transverse Strain.

ϵl is the Longitudinal or Axial Strain.

By Gokula Srinivasan Selvam

Gokula Srinivasan Selvam is a Material Testing Associate at MaTestLab Inc. and holds a postgraduate degree in Ceramic Engineering from IIT (BHU),...