ULTRASONIC EVALUATION ON FAILURE OF CARBON FIBER REINFORCED COMPOSITE MATERIALS

The static tensile tests of carbon fiber reinforced composite specimens ([O°],[1±45°],[0°/90°]_s)without notch,with double edge notch,central hole and central notch have been investigated experimentally. Using ultrasonic scanning and imager method,internal damage and damage persentage in different loading regions of carbon/epoxy composite were detected.The curves of loading-damage percentage and pictures of internal flaw distribution in different depths were obtained.The results show that during static tensile test,the crack propagates along tha direction of the fiber interface instead of that of the edge notch in specimen.The notch doesnot affect the load-bearing capacity of ligament of the specimen.For the specimen with central notch,interface crack occurs at the tip of the notch And the specim en with central hole,damage initiates around the hole, later,it extends along the fiber direction.In this paper. the failure mecha nism is analysed also.