AN EXPERIMENTAL MICROMECHANICS MEASUREMENT TECHNIQUE FOR SUBMICROMETER DOMAINS

Orthogonal arrays of dots applied to surfaces can be used to directly measure microscopic strain fields. The spatial and strain resolution a re both limited by the size of the dots placed on the surface. Two tec hniques using the beam of a scanning electron microscope (SEM) have be en developed which make possible the placement of very fine dots with diameters of only 0.5 and 0.02 mu m, respectively, on the surface of t he specimen, allowing local strain measurements on the scale of 0.2-10 mu m when specimens are loaded in the SEM. Measurements of strains fi elds around the tips of growing cracks in both polymers and polymeric composites are presented to illustrate the capabilities of the techniq ue.