Abstract: In order to investigate the effects of stratified evolution and delamination on the load capacity and service life of the composite materials under the four-point bending load, the artificial tectonic defects of the different positions were set up. The four-point bending test was carried out, the whole process was recorded by acoustic emission, and the degree of damage for the composite material was judged by the collision accumulation-time-amplitude history diagram, load-time-relative energy history diagram, acoustic emission impact signal location diagram and so on. The results show that the stratification defects near the surface of the specimen accelerate the process of material failure and expansion. The location of the delamination defect changes the bending performance of the composites to a great extent. The closer the stratification defects are to the surface of the specimen, the greater the damage, the worse the service capacity of the specimen.

Key words: composite, delamination damage, four-point bending, acoustic emission