复合材料；后屈曲；盒段；有限元法, 多墙；中厚蒙皮

The bending static experiments and FEM were used to study the post-buckling performance of a composite thick-skin multi-spar wing box. The well agreements of the load-displacement curves between experiment and FEM show the FEM modeling is credible. Based on this FEM model, the post-buckling behaviors of the wing box under two different loads: concentrate and press load, were investigated. The buckling behaviors were determined by tracing the load-deflection curves using non-linear arc-length method. Numerical results present the critical load,buckling deformation behaviors,the stress distribution and the destroy process. 

composite material, post-buckling, wing box, finite element method(FEM), multi-spar, thick skin