BOUNDARY-LAYER TRANSIENT HYGROSCOPIC STRESSES IN ORTHOTROPIC THICK SHELLS UNDER EXTERNAL-PRESSURE

An exact elasticity solution is obtained for the stresses and displace ments in an orthotropic cylinderical shell loaded by an external press ure under imposed constant moisture concentrations on the inner and ou ter surfaces. The material properties are assumed moisture independent and a displacement approach is used. Since the moisture diffusion pro cess is relatively slow, the hygroscopic stresses are confined for pra ctical time values to a boundary layer region near the surfaces. Illus trative results are presented for graphite-epoxy material regarding th e boundary layer hyperscopic on the stress field with respect to time and the coupling of mechanical loading (external pressure) and moistur e diffusion. For this material, it is shown that this effect is more p ronounced for the axial component of stress.