Modeling and Computer Simulation of the Compressional Behavior of Fiber Assemblies

Abstract

In this study, the model presented in Part I is used to investigate phenomena related to the compression of fiber assemblies that are not accounted for by van Wyk's theory of the uniaxial compression of an initially random fiber assembly. In order to do this, the potential energy, the work done on the assembly, and a discrete orientation density function for the assembly are calculated. Realistic looking hysteresis plots are produced. and the model can predict the amount of frictional energy dissipated as a function of time. Irrecoverable compression does not increase for as many cycles as has been experimen tally reported, which may be a result of the neglect of viscoelastic effects. Crimp has a large effect on the compressional properties, in that more highly crimped fibers absorb more energy as they are compressed. They also absorb a higher proportion of their energy in the twisting mode, which previous investigators have neglected. A lower induced orientation effect than that resulting from Stearn's theory [12] is predicted, but this discrepancy cannot currently be resolved. Future work may incorporate viscoelasticity into the model and predict the most probable initial volume fraction for an assembly with given fiber properties.