A rotating composite thin-walled beam structure usually works in environment with strong hygrothermal characteristics. Temperature variation and moisture absorption can influence physical properties of composite, and furthermore change mechanical behavior of the structure. Hygrothermal influences depend on composite, layup scheme, geometry and nonlinearity of the beam. However, a comprehensive analytical model including these factors is lacking. This work aims to establish such a model for rotating composite thin-walled beams subjected to hygrothermal effects so that relevant problems can be solved analytically, which can aid numerical simulation and experimental test. Many important factors including hygrothermal effects, nonlinearity, mode coupling, arbitrary layup schemes, rotation, external forces, transverse shear, non-uniformity of cross section, constrained torsion, warping, setting angle and pretwist angle are considered. Governing equations of the coupled vibration are established by using the generalized Hamiltonian principle. Reduction verification, simplification principles and reduced models are discussed. The solution of the model is illustrated and some examples are given. Finally, the influences of temperature, moisture absorption and ply angle on hygrothermal internal forces of constrained thin-walled beams with CUS and CAS configurations are analyzed.

Thin-walled beam; Hygrothermal effects; Nonlinearity; Rotation; Layup scheme; Coupling