MICROMECHANICAL INVESTIGATIONS ON THE DAMAGE PROCESS IN CONTINUOUS FIBER REINFORCED PLASTICS (FRP) UNDER CYCLICAL LOADING

摘要

High-performance components made of continuous fiber-reinforced plastics (FRP) are generally subjected to stochastic cyclic stress during their service life. Therefore it is essential to understand the damage mechanisms of FRP under cyclic loading so that a reliable prediction of the fatigue life can be made.rnDue to the inhomogeneous structure of FRP, the damage behavior of a lamina is characterized by diffuse damage mechanisms, such as filament break, micro crack at the fiber/matrix interface and in the matrix. Previous investigations have revealed that the fatigue of unidirectional FRP under transverse loading is influenced by the stress redistributions in the matrix due to the creep and relaxation processes of matrix.rnIn this paper, the results of numerical and experimental investigations will be discussed, which include the modelling of matrix creep and the subsequent simulations of the stress redistribution and interface damage possibilities on a micromechanical scale. Experimental investigations were carried out on specimens with cyclic loading transverse to the fiber direction. The simulation results correspond well with the creep phenomena and damage investigation in experiments. The comparison between simulation and fatigue tests indicates a correlation between the stress redistribution in the matrix and the damage phenomena of FRP.