Standard Test Method for Photoelastic Measurements of Birefringence and Residual Strains in Transparent or Translucent Plastic Materials

Importancia y uso:

5.1 The observation and measurement of strains in transparent or translucent materials is extensively used in various modeling techniques of experimental stress analysis.

5.2 Internal strains induced in manufacturing processes such as casting, molding, welding, extrusion, and polymer stretching can be assessed and parts exhibiting excessive strains identified. Such measurements can lead to elimination of defective parts, process improvement, control of annealing operation, etc.

5.3 When testing for physical properties, polariscopic examination of specimens is required, to eliminate those specimens exhibiting abnormal internal strain level (or defects). For example: Test Methods D638 (Note 8) and D882 (Note 11) recommend a polariscopic examination.

5.4 The birefringence of oriented polymers can be related to orientation, shrinkage, etc. The measurements of birefringence aid in characterization of these polymers.

5.5 For many materials, there may be a specification that requires the use of this test method, but with some procedural modifications that take precedence when adhering to the specification. Therefore, it is advisable to refer to that material specification before using this test method. Table 1 of Classification System D4000 lists the ASTM materials standards that currently exist.

Subcomité:

D20.10

Referida por:

C1901-21E02

Volúmen:

08.02

Número ICS:

71.080.99 (Other organic chemicals)

Palabras clave:

birefringence; photoelastic measurements; photoelastic retardation; strain; strain-optical constant; transparent plastics ;