The article is focused on the investigation of interlaminar fracture toughness (IFT) of CFRP modified by SWCNT with 0.1–0.5 wt% concentrations. Mode I IFT is negatively affected by the addition of SWCNTs demonstrating the decrease by 16–46% depending on content. Mode II IFT testing showed a positive influence of SWCNTs resulting in the improvement of IFT up to 35%. The results of these mechanical tests and SEM data along with data of previously conducted research are jointly treated and possible reasons for this behavior are proposed and discussed.

Possibilities offered by an ultrasonic inspection technique that is based on using Lamb waves for monitoring the state of metal materials under static and cyclic loading have been studied. Dogbone...

The paper presents the results on application of Lamb waves based technique for impact damage detection and severity identification. The PZT network operates in the round-robin mode changing the actuator and sensor roles of the transducers in order to detect the response of the system in the presence of damage. The monitoring is performed via the analysis of three parameters: change of the amplitude (dA), change of the energy (dP) and cross-correlation (NCC) of the signals in baseline and damaged state. Testing of laminate CFRPs shows that the damage location is estimated with an error of 5–15 mm, while the computed Damage index is linearly dependent on the applied impact energy. For honeycomb CFRPs the NCC parameter do not provide accurate results, however, other parameters allow identification within the 5–20 mm error and reflect accurate data on the severity of the damage.

The deformation and fracture of specimens of a carbon-carbon composite material with different dimensions of a stress concentrator in the form of a central hole with diameters of 7, 10, and 13 mm were studied using a developed combined method. The results of a numerical analysis of experimental data are presented in the form of diagrams (dependences) of the shear-deformation intensity and the acoustic-emission activity as functions of the loading time. The factors that cause similarity and differences of the investigation results are discussed and interpreted. It is proposed that the obtained data be used for the nondestructive testing of composite materials via the selection of characteristic stages of the deformation development and the moment that precedes fracturing.