PSI - Issue 5

Andrzej Katunin et al. / Procedia Structural Integrity 5 (2017) 416–421 Andrzej Katunin/ Structural Integrity Procedia 00 (2017) 000 – 000

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plate are dominating, and therefore damage is initiated on surfaces and propagates following the direction to the middle plane.

4. Conclusions

In the presented study the evolution of a fracture mechanism in polymeric composites subjected to fatigue with the self-heating effect was analyzed. For this purpose, the specimens made of a GFRP composite were cyclically loaded up to reaching specified values of a self-heating temperature and then scanned using XCT. Application of advanced image processing methods on the acquired sets of planar slices enabled obtaining full 3D views of the tested structures including their internal architecture as well as classification of regions being delaminations and matrix cracks. Analysis of all the specimens allowed determining a new value of critical self-heating temperature of 60°C, i.e. causing initiation of internal fractu re in a structure, which is lower than the one determined using other methods in the authors’ previous studies. This outcome has been confirmed by comparison with the self-heating temperature history curves as well as values of residual ultimate tensile strength of the tested specimens. Furthermore, the analysis enabled determining the fatigue failure mechanism during fatigue of polymeric composites accompanied with the self-heating effect. In particular, it was noticed that damage propagates along the thickness from both external surfaces of a specimen to its middle plane, which is in accordance with the theoretical statements of bending of plates. The performed study with use of XCT has brought promising results and enabled better understanding of formation of fracture in a structure subjected to fatigue with the self-heating effect. This convinces to perform further research in this area that will be focused on a more detailed and quantitative analysis of damage propagation.

Acknowledgements

The results presented in this paper have been obtained within the framework of research grant No. 2015/17/D/ST8/01294 financed by the National Science Centre, Poland.

References

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