Abstract

Global local analysis is a part of the structural analysis that allows to study, with an iterative solution, a coarse global linear model with a specific zone. This zone is defined as a local model with fine mesh and a non-linear behaviour such as crack propagation. However, the current trend in Global Local analysis is to impose displacements on the fine model to later obtain the reactions that will be applied to the global model for each iteration (Primal to Dual solution algorithm). Therefore, we propose a mixed analysis in the local and global models through the application of Robin conditions on the interface, allowing a higher grade of flexibility for the case of the patch or fine model with crack propagation behaviour. As a result, the algorithm converges successfully, presenting kinematic compatibility and good results with respect to the Monolithic (non-decomposed) model. Finally, a sensitivity analysis is performed on some variables regarding the crack propagation for 2D models. Finally, the proposed methodology also allows to improve the performance of the method for cracked models or other nonlinearities when compared with the current global local analysis, presented in the state of the art.

Abstract

A new software, Geomiso TNL, is proposed to facilitate the use of isogeometric analysis and 3D design with NURBS and T-splines. Its dual nature eliminates geometric errors by merging geometric design with mesh generation into a single procedure. It is based on the isogeometric method, the powerful generalization of the traditional finite element method. This paper presents four sample applications in non-linear solid and structural mechanics. This software is seen to handle these situations remarkably well, as the numerical examples exhibit significantly improved accuracy of the results, such as displacement, strain and stress fields, and reduced computational cost when compared with finite element analysis. It is argued that Geomiso TNL is a new, more efficient, alternative to finite element software packages and possesses several advantages.

Abstract

Today’s merchant and passenger vessels are complex structures that operate in harsh environments with respect to static and cyclic loads and corrosion. Depleting funds for fleet renewal and increasing through-life cost of maintenance and repair are the principal factors that lead to the need to implement new solutions that are easy to apply and low cost. All this added to the growing need for lightening in the transport sector turn the FRP materials into the main candidates as drivers for this change.

This present study within RAMSSES is focused on the compare a damage steel structures to repair composite patches. A representative structural detail of a cruise vessel was selected and designed as a demo case. The best patch solution was selected by FEM calculations, which have been fed from the mechanical test results of the composite material combinations, steel, surface treatments and adhesion joint of the one-shot dissimilar joints without adhesive.

Fatigue tests have been carried out and monitoring by strain gauges and FBGs positioning and distribution in the high stress areas along the demonstrator. Fatigue tests have been carried out in the six demos to compare crack evolution in cracked Patched and Un-Patched demonstrators.

As conclusion after the fatigue tests, composite patch works as crack arrested. Therefore, this behaviour represents an improvement of the 2.6 times of the fatigue life comparing UnPatched and Patched damaged steel.