APPLICATION OF MICROLINE GRID METHODS TO TEMPERATURE-DEPENDENT MICROSCOPIC DEFORMATION AND DAMAGE IN CFRP LAMINATES/

Tensile tests of CFRP symmetric cross-ply laminates are carried out in a scanning electron microscope (SEM), and microscopic interlaminar de formation and damage near the transverse crack tip are visualized by m icrolines or microgrids printed on the specimen edge surface. The loca l deformation around the transverse crack tip is observed at 20 degree s C, 80 degrees C, 120 degrees C and 160 degrees C to evaluate the eff ect of thermal residual stress on the microscopic deformation and dama ge in the interlaminar region near the transverse crack tip, Temperatu re dependence of the axial crack opening displacement (GOD) is also me asured. The displacement field of the specimen edge surface obtained f rom these experimental results is compared with the theoretical model proposed by Lee, Alien and Harris. The analysis is modified to conside r the temperature effect, and a good agreement is obtained between the modified theoretical predictions and experimental results.