Stress rupture of unidirectional high performance thermoplastic composites in end-loaded bending at elevated temperatures. Part I: Experimental characterization of the failure mode.

Macro- and micro-observations of unidirectional thermoplastic composites under end-loaded quasi-static bending have been made. The presence of stable microbuckles has been identified on the compressive side of the specimen. The formation of the microbuckles has been videotaped. Frames of this film are examined and the failure process is identified. The stress rupture of these specimens at elevated temperatures in bending seems to be driven by the formation and propagation of microbuckles. Videotaping from a different angle also gives information on the change of shape of the bent specimen in the oven as a function of time. These unique data form the basis for an understanding of the stress rupture of unidirectional thermoplastic composites in bending that was not previously available.