Comprehensive evaluation of fatigue damage accumulation and failure of specimens with operational stress concentrators

The paper presents the results of studying the mechanical behavior of laminated carbon-fiber-reinforced plastic under complex low-velocity impact three-point bending followed by cyclic tension. An integrated approach to studying damage accumulation patterns is implemented with the use of state-of-the-art testing and diagnostic equipment. The residual fatigue life of the composite is related to the intensity of preliminary impact bending. The fields of temperature distribution in the active zone of the samples during the tests are shown. Data on damage accumulation obtained by recording acoustic emission signals are presented. Relation of the change in the recorded acoustic response signals to infrared thermal scanning data has been detected, which is supported by the results of an experimental study. The use of additional equipment for infrared thermal scanning and recording of acoustic emission signals gives a complete picture of damage accumulation and failure in composite materials, with a good agreement with experimental data.