Recently, composite materials are used in many fields because their properties are high
strength, high stiffness, and they have light weight, good corrosion resistance and good thermal
conductivity. However, composite materials have relatively a lot of problems, especially
delamination, compared with common materials such as a steel and aluminum, etc. Therefore, having
the interlaminar fracture toughness for a laminate composite is important. In this study, the end
notched flexure (ENF) specimens are employed in order to evaluate modeⅡ interlaminar fracture
toughness for CFRP laminate composites. Three kinds of a/L ratio were applied to these specimens
under the different pressure level. Also, we discuss the relation of crack growth and the interlaminar
fracture toughness in terms of AE characteristics using ENF test.