Deformation and failure of polymer composite materials under preliminary cyclic and low-velocity impacts

Abstract

The paper presents the results of an experimental study of the behavior of samples of polymer composite materials under complex mechanical loads. A technique has been developed for the experimental assessment of changes in the residual strength and stiffness properties of layered composites for various parameters of preliminary cyclic and low-velocity impacts. Corresponding experimental data were obtained for fiberglass samples with various layouts. In accordance with the considered method for analysis of the obtained data, a fatigue sensitivity diagram has been introduced, which contains the characteristic sections of the change in the residual static strength and its threshold values, and is used to study the processes of damage accumulation and fracture of composites at various loading parameters. The results of a study of the effect of preliminary shock tension on the processes of deformation and fracture of fiberglass samples are presented. As a result of the analysis of the influence of a preliminary three-point impact bending on the mechanical characteristics of fiberglass specimens during tension, a threshold value of impact sensitivity was noted, until which a decrease in the residual strength of fiberglass was not observed. A change in the mechanisms of destruction of the samples under static tension with an increase in the energy of preliminary impact is noted.