FATIGUE BEHAVIOR OF GLASS BEAD FILLED EPOXY

There is a relatively abundant literature on the mechanical properties of particle filled thermosets. Detailed experimental data are availab le on the effect of variables, such as the filler volume fraction, its surface treatment or shape factor, on the usual properties. In the ca se of epoxy matrix composites, data have been published on elastic pro perties. Kinetic studies on thermoplastics, as well as microscopic inv estigations clearly show that each particle acts as a crack initiation site. The present study deals with thermoset epoxy-glass bead composi tes. A noticeable advantage of the sphericity of the glass beads over the previously studied mineral fillers is that theoretical calculation s, for instance of interparticle average distance, are easier. Some re sults are reported concerning the eventual role of the geometrical cha racteristics, including particle diameter, number of particles per vol ume unit, particle-matrix contact area, interparticle distance, on the fatique characteristics of the composite as assessed from Paris or Wo hler plots. In addition, quasi-static crack propagation characteristic s will be compared with dynamic ones. It is clearly shown that glass b eads im proved the fatigue crack propagation. Despite this fact, it is also shown that even a small amount of mineral filler, acting as crac k initiator, can considerably reduce the fatigue life of epoxy composi tes.