FAILURE ANALYSIS AND DAMAGE INITIATION IN CARBON-CARBON COMPOSITE-MATERIALS UNDER 3-POINT BENDING

Carbon-carbon composite materials offer designers a significant improvement over conventional materials for advanced turbine engine applications. However, these composite components must be attached to other components which is usually done using mechanical fasteners. These attachments create contact stresses, which in turn lead to a variety of failure modes and damage. In order to characterize these failure modes and damage mechanisms a three-point bend test was employed. This test has been widely studied by many researchers and provides a wealth of comparative data. In addition it is the simplest mechanical and experimental model of a contact problem. This study focused on determining damage initiation and failure mechanisms in woven uncoated carbon-carbon composite laminates resulting from the three-point bend test. Failure modes and damage initiation sites for short and long beam geometries were determined.