PSI - Issue 18

Staroverov Oleg A. et al. / Procedia Structural Integrity 18 (2019) 757–764 Staroverov O.A., Wildemann V.E., Tretyakov M.P., Yankin A.S./ Structural Integrity Procedia 00 (2019) 000–000

762

6

n’ = 0

n’ = 0.8

Fig. 6. Photos of the surface of the working area of fiberglass samples

Research of the effects of various cyclic effects on the residual strength and deformation properties of samples of fiberglass composite materials with different reinforcement layouts were carried out in the framework of the state task of the Ministry of Education and Science of Russia (9.7526.2017 / 9.10). 5. The effect of preliminary shock loads of varying intensity on the nature of the destruction of carbon-fiber sample plates As part of the study, the impact of the preliminary impact on the deformation properties of carbon-fiber specimens was evaluated. For example, Figure 7 shows loading diagrams of sample plates with a spatial reinforcement scheme for compression after impact with different energies from 30J to 50J. The impact energy values corresponded to the appearance of visible (30 J) and significant (50 J) damage on the sample surface, but not cross-cutting. The mass of the impactor remained constant, varying the height of the discharge and the speed of the fall.

Fig. 7. Typical loading diagrams of sample plates (1 – without impact; 2 – impact 30 J; 3 – impact 40 J; 4 – impact 50 J) the dashed line indicates the zones of dynamic destruction

Additional pre-shock impact significantly affects the behavior of the sample plates of a composite material at the supercritical deformation stage during the fracture process. Even though the impact reduces the value of the maximum breaking load (P, kN) under compression, the length of the equilibrium deformation section is more pronounced. A preliminary impact with an intensity of 30 J allows one to obtain a longer loading curve at the stage of supercritical deformation without failures associated with the transition to dynamic fracture (Fig. 7, curve 2). Conclusion As a result of the experimental study, new data were obtained on the effect of various modes of preliminary complex cyclic, shock loads on the deformation and destruction of polymer composite materials with various reinforcement layouts. When analyzing the results of the study of glass-plastic specimens with various layouts with successive cyclic and static loading, it was revealed that the phased nature of changes in the residual strength and