Initial matrix cracking influence on load-carrying ability of carbon fiber specimens | Mekhanika | kompozitsionnykh | materialov i konstruktsii
> Volume 23 > №2 / 2017 / Pages: 225-232

Initial matrix cracking influence on load-carrying ability of carbon fiber specimens

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Abstract:

The airworthiness requirements specify that ultimate loads be carried by the structure without failure. That is why one must take into account initial matrix cracking. The primary aim of this work was investigation of initial matrix cracking in carbon fiber specimens. The specimens were made from carbon fiber composite material VKU-30. This material has shown relatively good toughness as compared with other composite materials. Two panels with different layups were made. A batch of specimens for test program was made from each panel. After definition of the ultimate tensile load all of the remaining specimens were divided into two groups. The first group was for reference samples, the second one was for loading in tension under 89% of tension fracture load. Each of these specimens was subjected to contact laser ultrasonic evaluation before and after test and also before and after machining. Then (after tension loading under 89% of tension fracture load) the other specimens from two groups were cut out for compression strength test and short-beam strength test except specimens which were subjected to microscopy. No initiation of interlaminar cracking was detected by the instrumentality of microscopy. Cutout specimens were loaded to failure. Also no considerable result differentials between two groups were revealed.

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