Conclusions for buckling of plates with transversal imperfections

The FEM based methodology and the experimental test program were successfully developed for the investigation of buckling problems of composite plates. The FEM model is robust in that it can be used to predict the global buckling loads of composite plates either on one side or both sides. Finite-elements analysis and experimentation were carried out to assess the reliability of the methodology. The buckling behaviour of the orthotropic composite plates is different than the buckling behaviour of the isotropic plates. A special remark is to do for the plates having initial transversal deformation: the transversal deformation is increasing since the in-plane load starts to increase.

The buckling load determination is too difficult without applying a graphical method, or applying the Tsai-Wu failure criterion.

So, for a plate with transversal imperfection, since the magnitude of the initial transversal deformation is increasing, the value of the force for compression failure or tension failure of an element is decreasing.

The lack of the criterion is referring to the anticipation of the real mode to occurring the cracking.

Taking into account the mathematical formulation, the Tsai-Wu failure criterion is easy to be applied. Additionally, this criterion offers advantages concerning the real prediction of the strength at variable loadings. It is to remark that by applying linear terms, it is possible to take into account the differences between the tension and compression strengths of the material.

A good correlation between the numerical and experimental results is concluded.