Introduction

The term ‘flexible composites’ is used hereinafter to identify composites based upon elastomeric polymers of which the usable range of deformation is much larger than those of the conventional thermosetting or thermoplastic polymer-based composites (Chou and Takahashi 1987). The ability of flexible composites to sustain large deformation and fatigue loading and still provide high load-carrying capacity has been mainly analyzed in pneumatic tire and conveyor belt constructions. However, the unique capability of flexible composites is yet to be explored and investigated. This chapter examines the fundamental characteristics of flexible composites.

Besides tires and conveyor belts, flexible composites can be found in a wide range of applications. Coated (with PVC, Teflon, rubber, etc.) fabrics have been used for air- or cable-supported building structures, tents, parachutes, decelerators in high speed airplanes, bullet-proof vests, tarpaulin inflated structures such as boats and escape slides, safety nets, and other inexpensive products. Hoses, flexible diaphragms, racket strings, surgical replacements, geotextiles, and reinforced membrane structures in general are examples of flexible composites.

Following Chou (1989, 1990), the nonlinear elastic behavior of three categories of materials is examined: pneumatic tires, coated fabrics, and flexible composites containing wavy fibers. These materials provide the model systems of analysis with elastic behaviors ranging from small to large deformations.

The performance characteristics of pneumatic tires are primarily controlled by the anisotropic properties of the cord/rubber composite. The low modulus, high elongation rubber contains the air and provides abrasion resistance and road grip. The high modulus, low elongation cords carry most of the loads applied to the tire in service.