Residual Stress Measurement of the Engineering Plastics by the Hole-Drilling Strain-Gage Method

The hole-drilling method is regulated as the ASTM E837 standard and has been widely used for the residual stress measurement of metallic materials. We applied this method to orthotropic plastic specimens. Known stress distributions with depth were given by the four points bending tests and the calculated stresses from the measured relieved strains were compared with the given values analyzed by the beam theory. Consequently, the calculated uniform stresses based on both orthotropic and isotropic approaches were equivalent to the beam theory analyses. In addition, the calculated non-uniform stresses with depth in accordance with ASTM E837 standard agreed well with the beam theory values. It was confirmed that the residual stress measurement by the hole-drilling method is effective for the orthotropic plastic materials.