Agnieszka Bondyra

Numerical and experimental buckling and post - buckling analysis of composite cylindrical panel with delamination

The present work is devoted to the analysis of a buckling behavior of a cylindrical composite panel. The considered structure is subjected to the uniform axial compression. The wall of the panel consists of the 8 layers. In addition, in the geometrical center of the structure there is a square delamination located between the fourth and the fifth layer. The main goal is to determine the buckling and post - buckling behavior as well as the influence of the delamination on the stability of the structure. The nonlinear numerical analysis is carried out with aid of the FEM method. The experimental verification is also performed. The results obtained from numerical and experimental analysis show very similar behavior of the structure.

Modelling of fatigue damage evolution in composite multilayered cylindrical shells

This work presents modelling and numerical analysis of shells with axisymmetric or embedded elliptic delaminations. Numerical studies are conducted including cyclic buckling, contact problems in the post-buckling range and optimisation problems associated with searching from the minimum of the crack growth per one cycle. Finally, the fatigue life is estimated with the use of the fuzzy set approach.

3D scanning inspection of the composite structures

Wide range of different visual measurement techniques, which are used nowadays, shows the need of the development of geometry description possibilities. New applications of advanced materials require measurement methods, which can be used in the areas of reverse engineering, FEA modelling validation, rapid prototyping and analysis of structure deformations. Light and laser-based techniques such as photogrammetry, laser triangulation, Moire and optical coherence tomography allow for analysing geometry of the specimens. Widely used optical methods take into account the global and local coordinate translation, sensitivity, resolution, and measurement uncertainty. They are used in the respect to research trends such as direct shape measurement from surfaces, system calibration and optimization methods. In this paper, composite specimens’ geometries with artificial delamination inside and structures without delamination are analysed. Rectangular, curved and cylindrical shapes are investigated by 3D scanning technique. The measured composite structures are manufactured with autoclave and vacuum bag methods. Results presented in this paper, shows geometries different between composites manufactured by using these methods. Inspection process was executed in two steps. First, virtual models of the composite specimens are used to determine main geometry dimensions. Second, their curvatures and GD&T are determined. Additional, the thickness change connected with delamination is revealed. Used method gives an opportunity of observing specimens curving radius and manufacturing defects. Presented results shows that use of additional aluminum plate in vacuum bag method allowed to get specimens with high level of flatness and parallelism in the case of rectangular structures and cylindricity in case of the curved shells. Presented methodology of the inspection is simply, give multidimensional results and its application are not limited to laboratory conditions.