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Strain Gage Measurements on Plastics and Composites

Properties Data for Plastics/Composites

In its usual mode of application, experimental stress analysis begins with the measurement of presumed significant strains in the test part under some set of actual or simulated service loads. The resulting data are subsequently converted to stresses, using the appropriate system of constitutive relationships. Finally, the stresses thus inferred are compared to pre-established norms, or allowable values, consistent with the expected service life and environment for the product.

The stress/strain relationships employed in this process generally require, as a minimum, the elastic modulus and Poisson's ratio of the material in the test part; and, for anisotropic materials, the directional characteristics and shear properties are needed as well. Additional parameters may be involved if the material is nonlinear in its elastic properties, or if the properties vary measurably with time, temperature, or moisture content.

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