Modeling the stress/strain behavior of a knitted fabric-reinforced elastomer composite

This paper presents a micromechanical analysis procedure for predicting the stress/strain behavior of a composite made of weft-knit polyester fiber in terlock fabric and a polyurethane elastomer matrix. For analysis, a represe ntative volume element (RVE) of the composite was initially identified. The RVE was divided into a number of sub-volumes, each of which was considered as a unidirectional fiber-reinforced composite oriented according to the f iber architecture in the RVE, The analysis was then carried out for such a unidirectional composite by using a bridging matrix that correlates the str esses generated in both the fiber and the matrix materials. The bridging ma trix is sensitive to the geometrical and physical properties as well as the constitutive relationships of the fiber and matrix materials. The Prandtl- Reuss theory was used to describe the elasto-plastic behavior of the polyes ter fiber and an accurate incremental theory was applied to represent the r ubber-elastic constitutive relationship of the polyurethane matrix. A volum e-average scheme was used to assemble the contributions of all the sub-volu mes to obtain the overall response charecteristics of the RVE. By means of the bridging matrix, the stress state of each constituent phase of the comp osite is explicitly known at every load step. The procedure was repeated fo r a series of load increments to obtain the stress/strain behavior of the c omposite. A strength criterion based on maximum normal stress theory was ap plied to determine the maximum load that the composite can sustain. The pre dicted stress/strain behavior is validated by comparison with experimental data. (C) 2000 Elsevier Science Ltd. All rights reserved.