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"Effects of Defects" in Multiaxialgelegen unter mehraxialer Belastung

Subject Area Lightweight Construction, Textile Technology
Term from 2008 to 2020
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 59122888
 
Final Report Year 2016

Final Report Abstract

A wide data base on the fatigue of composites under both, uniaxial and multiaxial loading has been established, taking into account a set of defects, as e.g. voids, impacts and fibre waviness. A deep understanding of the phenomena and mechanisms occurring in these cases has been achieved. Modelling tools were developed for fatigue degradation and describing the influence of single voids on composites properties. The comparison of coupon tests with multiaxial tests on stringer stiffened panels (demonstrator test) showed, that the behaviour of internal damages as voids or impacts can already well be studied on the coupon level, however, a final verification on its influence on the level of panels is evident, as here further influencing factors from the specific panel geometry and design (stiffeners) have to be considered. Pressure modulated lockin-interferometry successfully allowed to detected damage in GFRP tubes. Sensitivity of the air-coupled guided waves method has to be increased to detect fatigue damage in CFRP, because the measurable effects appear to be smaller than in GFRP. The effects of higher guided wave modes need to be better understood to exploit them for damage characterization. For the NDT investigation of damage and its development on the panel level adapted systems have to be developed which take the panel geometry into account. They have to be further extended to also examine areas close to the fixation in the multiaxial test rig.

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