No abstract

The use of laminate carbon fibre composite materials has been growing in a substantial way in the last decade. Some industries like the aerospace, aeronautical, automotive and biomedical benefit from the introduction of new structural solutions that became possible by using these materials. However, during the life in service of the composite components the material is exposed to a great variety of external attacks. Casual impacts, heat variations and water ingestion may provoke invisible degradation that can lead to a posterior collapse. For this reason the detection of eventual defects is very important and its inspection using non-destructive techniques of primordial importance. In this paper is proposed the use of holographic interferometry techniques for non-destructive detection of defects caused by low velocity impacts in laminate carbon fibre composites.

In this paper analytical solutions for displacements and stresses in spherical shells over rectangular areas are developed. The analysis is based on spherical shallow shell equations, and solutions are obtained through the use of double Fourier series expressions to represent the displacement and loading terms. Three types of loading were considered: radial load, overturning moment and tangential shear. In order to test the results, an experiment and nite element investigation has been carried out to determine the state of stress in a spherical shell model and results are compared in graphs. The proposed solution is also applied to compute the local stresses around a support leg in a spherical shell, and results are compared with those obtained by the Bijlaard method used in American code ASME VIII, Part 2, and British code PD 5500:2000.

Numerical simulation of static indentation and lateral impact tests of carbon/epoxy laminated composite plates, using ADINA finite element system is presented. The geometry, loading and boundary conditions used in simulation were determined by the drop test Rosand system that will be used to compare numerical results. Unidirectional and several 0/90 ply orientations stacking sequences carbon/epoxy plates were used in order to study the influence of thickness and ply orientation on the deformation and failure of the plates. Linear and nonlinear static response analyses were considered in the simulations of displacements and the extent and nature of damage. In the development of these studies, combined use of finite element analysis and impact testing is necessary to assess the damage tolerance of composite components. Afterwards, by parametric studies, it will be possible to study in a systematic way the effects of thickness, shape, ply orientations and duration of impact on deformation and failure of the plates.