Search results for " Buckling"
showing 6 items of 26 documents
Composite laminates buckling optimization through Levy based Ant Colony Optimization
2010
In this paper, the authors propose the use of the Levy probability distribution as leading mechanism for solutions differentiation in an efficient and bio-inspired optimization algorithm, ant colony optimization in continuous domains, ACOR. In the classical ACOR, new solutions are constructed starting from one solution, selected from an archive, where Gaussian distribution is used for parameter diversification. In the proposed approach, the Levy probability distributions are properly introduced in the solution construction step, in order to couple the ACOR algorithm with the exploration properties of the Levy distribution. The proposed approach has been tested on mathematical test functions…
Accurate Multilayered Shell Buckling Analysis via the Implicit-Mesh Discontinuous Galerkin Method
2022
A novel formulation for the linear buckling analysis of multilayered shells is presented. High-order equivalent-single-layer shell theories based on the through-the-thickness expansion of the covariant components of the displacement field are employed. The novelty of the formulation regards the governing equations solution via implicit-mesh discontinuous Galerkin method. It is a high-order accurate numerical technique based on a discontinuous representation of the solution among the mesh elements and on the use of suitably defined boundary integrals to enforce the continuity of the solution at the inter-element interfaces as well as the boundary conditions. Owing to its discontinuous natur…
Buckling and post-buckling of variable stiffness plates with cutouts by a single-domain Ritz method
2023
Structural components with variable stiffness can provide better performances with respect to classical ones and offer an enlarged design space for their optimization. They are attractive candidates for advanced lightweight structural applications whose functionalities often impose the presence of cutouts that requires accurate and effective analysis for their design. In the present work, a single-domain Ritz formulation is proposed, implemented and validated for the analysis of buckling and post-buckling behaviour of variable stiffness plates with cutouts. The plate model is based on the first-order shear deformation theory with nonlinear von Karman strain–displacement relationships. The p…
Intravitreal dexamethasone implant for cystoid macular edema and inflammation after scleral buckling
2015
Purpose Cystoid macular edema may occur following scleral buckling and therefore deteriorate the visual outcome. Inflammation may be the major causative factor in the development of postoperative cystoid macular edema. This case demonstrates the effectiveness of a dexamethasone implant as a treatment after the onset of choroidal inflammation and cystoid macular edema 6 months following scleral buckling and having visual acuity restored. Methods A 59-year-old phakic woman treated with scleral buckling for macula-off retinal detachment presented 2 months after surgery with cystoid macular edema with choroidal inflammation. Optical coherence tomography and fluorescein angiography were performe…
Structural Design of Frames Able to Prevent Element Buckling
2012
Two formulations of a special multicriterion optimal design problem devoted to elastic perfectly plastic steel frame structures subjected to different combinations of static and dynamic loads are presented. In particular, two minimum volume design problem formulations are proposed: in the first one the structure is designed so as to be able to elastically behave for the assigned fixed loads, to elastically shakedown for serviceability seismic load conditions and to prevent the instantaneous collapse for suitably chosen combinations of fixed and ultimate seismic loadings; in the second one the structure must also satisfy further appropriate constraints related to element buckling. The action…
Scleral Buckling: A Review of Clinical Aspects and Current Concepts
2021
Scleral buckling represents a valuable treatment option for rhegmatogenous retinal detachment repair. The surgery is based on two main principles: the closure of retinal breaks and the creation of a long-lasting chorioretinal adhesion. Buckles are placed onto the sclera with the purpose of sealing retinal breaks. Cryopexy is usually performed to ensure a long-lasting chorioretinal adhesion. Clinical outcomes of scleral buckling have been shown to be more favorable in phakic eyes with uncomplicated or medium complexity retinal detachment, yielding better anatomical and functional results compared with vitrectomy. Several complications have been described following scleral buckling surgery, s…