Characterization of strain field distribution in carbon fiber reinforced resin matrix composites using electron beam moire and geometric phase analysis

The meso and nanoscopic deformation behavior of the carbon-fiber reinforced resin matrix composite during ten-sile loading were investigated via in situ scanning electron microscopy combined with the electron beam moire and geometric phase analysis (GPA) techniques. Electron beam lithography was used to fabricate a cross-grating with a pitch of 359 nm (2780 lines/mm) on the surface of the composite material to facilitate the direct measure-ment of the deformation. In situ observation of the composite subjected to tension were conducted to determine strain filed distribution under different loads. The global and local strain field were measured and analyzed at the meso and nanoscale. The strain field distribution around matrix transverse crack, cracks between fibers, inter-laminar cracks, and broken fiber cracks were characterized via GPA under load. The strain concentration factor and the ineffective length of the broken fiber were also measured experimentally.