Mechanism of Load and Deformation Transfer among Fibers in Composite Materials

Abstract

The processes that occur during loading and destruction of composite materials (CMs) are studied by the full pull-out method. The mechanisms of load and deformation transfer in CM and the effects of the plasma activation of fibers and of the matrix properties on them are ascertained. It is established that the transfer and distribution of load and deformation among fibers in CM occur via two adhesive joints of fibers with the matrix layer. Reinforcing fibers activated by nonequilibrium low-temperature plasma increase the specific absorbed-in-fracture energy from 26 to 44 J/cm2, the shear strength from 7.1 to 10.4 MPa, and the strain from 1.8 to 2.33%. When the maximum load and strain are reached, the CM is destroyed and the fiber is fired from the matrix. In the case of nonactivated fiber reinforcement, destruction of the CM occurs in two stages: first, the strength and deformation reach the limiting values and the fiber then begins to shift in the matrix, which causes stress relaxation and a sharp drop in strength of the CM. Further deformation occurs as a result of pulling fibers out of the matrix at low load. Plasma activation of reinforcing fibers leads to an increase in properties of the CM.