PSI - Issue 5

Tretyakov M.P. et al. / Procedia Structural Integrity 5 (2017) 233–238 Tretyakov M.P./ Structural Integrity Procedia 00 (2017) 000 – 000

238

6

Table 1. Crack opening displacement rate on descending section of the loading curves under various stiffness of the loading system. Total length of specimen ( mm )

Stiffness of the loading system ( kN/mm )

Crack opening displacement rate ( mm/s )

60 90

12.5

0.063 0.107 0.228

7.8 6.3

120

4. Conclusion

Experimental study of crack growth processes in glass-epoxy composite laminates is provided. The eccentric tension tests of compact specimens of composite laminates under various stiffness of the loading system were carried out. Descending sections of the loading curves of tension of compact specimens with crack were considered by analogy with postcritical deformation stage of materials. It is shown, that behavior of composite specimens with crack under tension depends on the loading system parameters: crack grows process is stable when stiffness of the loading system is enough, crack opening displacement rate increase under reduction of stiffness of the loading system. With future decreasing of the stiffness of the loading system, for instance with using of special shape specimens and test tool with various stiffness [Vildeman et al. (2011)], the crack growth process could become unstable and specimen with crack will failure straight after critical point (corresponds to maximum load). This effect should be take into account during modeling and analyzing of fracture processes of composite materials, strength and survivability assessment of composite structures in real loading conditions.

Acknowledgements

The work was carried out with support of the Russian Science Foundation (Project 16-19-00069) in the Perm National Research Polytechnic University.

References

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