21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-4.8.2

EFFECTS OF STRETCHING-BENDING COUPLINGS ON THE BUCKLING AND THERMAL BUCKLING BEHAVIOR OF UNSYMMETRIC LAMINATES

Cheng G. M., Tsao D.*
First Research Institute, Beijing, PRC; *Northwestern Polyt. Univ., Xi'an, PRC

Keywords: stretching-bending, couplings, thermal, unsymmetric, laminates

Implicit in the linear analysis of buckling behavior of isotropic plates, homogenous anisotropic plates, or symmetrically laminated composite plates ,are the three assumptions that " no additional inplane deformations take place in the process of buckling", " the external edged loads remain constant in the process of buckling", and "for a perfect plate, the plate remains plane before buckling onset" . In the authors' priori work, it was pointed out that the applicability of the above three mentioned assumptions are worth to be questioned to a buckling problem of unsymmetric laminates. To unsymmetrically laminated composite plates, due to the stretching-bending couplings, before buckling, inplane loads may cause a out-of-plane prebuckling deflection, while in the process of buckling, the bending of the plate may cause inplane deformations as well as the altering of edged loads. This phenomena is much similar to the way of buckling of shell panels. In the present paper, based on a higher order displacement theory including three midplane displacements ,one stretching of normal, two rotations of normals about the midplane and two warps of the normals, by using the variation principle, a formulation for both buckling and thermal buckling was derived from the system's total potential energy. The formulation accounts for all of the effects of inplane deformations, edged loads altering, and prebuckling deflection on the critical buckling loads .

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