Modeling for Suppression of Moisture/Temperature Induced Dimensional Changes in Unbalanced Fibrous Composite Structures with Periodic Bonding

Abstract

Suppression of dimensional change induced by moisture and temperature change is studied for unbalanced structures composed of at least one hygroscopic component. An unbalanced parallel structure with periodic bonding is modeled, taking into account various parameters such as moisture content and temperature at the time of assembly, molecular orientation, and bonding length. The results show that two factors play a major role in moisture/temperature induced dimensional change: longitudinal swelling/shorten ing and material softening/stiffening. Whether the two factors add their effects to each other or compete against each other depends on the moisture content and temperature at the time of structural assembly. There is a range of critical aspect ratios over which the structure is dimensionally stable. This range increases with increasing width and thickness ratios, and decreases with increasing initial moisture regain, initial temperature, and orientation factor.