BUCKLING STRESSES OF COMPOSITE TUBES UNDER BIAXIAL COMPRESSIVE LOADS

An analytical model describing the instability of specially orthotropi c composite tubes with geometric imperfections subject to biaxial comp ressive loads and under clamped-clamped boundary conditions is develop ed. Furthermore, the range of validity of the present solution is clar ified, and comparisons are made to some studies on isotropic cylindric al shells. Six E-glass woven fabric-epoxy composite tubes with the sam e internal radius and different thicknesses and longitudinal lengths w ere fabricated and subjected to various combinations of external hydro static pressure and axial compressive load simultaneously. The normali zed buckling stresses were found to agree in general with the theoreti cal predictions at various biaxial loadings. The buckling envelopes in normalization form provide useful design data on the strength of spec ially orthotropic composite tubes under a realistic range of biaxial l oading conditions.