By using fiber random distribution model constructed by finite element code Ansys, the computing
and analysis of transient moisture distribution were carried out after moisture transports into the aramid fiber/ epoxy
resin composites exposed to relative humidity RH = 90% at t =80益condition. The difference between the computed
results and the material absorption experimental results was minimal with the maximum difference being 2. 7% of the
weight gain. Then the analysis was carried out to study the timevarying moisture stress on the basis of obtained transient moisture distribution. The results show that finite element analysis approach can accurately simulate transient moisture transport of composites. The level of moisture stress is very high after a long term moisture absorption in resin matrix (above 50 MPa),and the stress in the matrix region of fiber spacing is smaller and the interface between matrix
and fiber is higher than that in other regions. The highest stress occurs in the interface. This high level of stress may
lead to significant effects on damage and failure initiation in the cycle moisture and drying.