Semi-discretization Analysis for the Shear-lag Model with a Viscoelastic Matrix and Its Application to Creep-rupture Simulation Using the BIS Method

摘要

A creeprupture simulation of continuous fiber-reinforced composites was proposed, based on a shear-lag model. This simulation model is composed of tension-carrying elastic fibers and shear- carrying viscoelastic matrix including the effect of stress history. Simultaneous integro-differential equations obtained from their force equilibrium were semi-discretized with respect to space coordi- nate and solved analytically with respect to time. The result showed that the unrecovered stress region and stress concentration region around a broked fiber were increased with time, similarly to a conventional anlaytical model. On the other hand, since the above equations are changed with each fiber breakage, it is uncertain which initial condition of the equations should be used in the simula- tion. To solve this problem, the break-influence superposition (BIS) method was applied to the simulation, in which independent solutions with different fiber breakage points are superposed with weight coefficients. It is proved that the BIS method can reasonably predict a complicated viscoelas- tic behaviour caused by initially and later broken fibers. Finally, the simulation was carried out for the composites reinforced by the fibers without time-dependent breakage to predict a possibility of creep-rupture.