Abstract

This paper presents a study of the flexural test, simply supported and two spans, necessary to establish the acceptance criteria of a sandwich panel of faces derived from wood, subjected to uniform load. Tests have been carried out on sandwich panels with CE marking and all of them have passed the European Technical Approval (ETA) evaluation process for the use for which they are specified. The results obtained in the experimental tests have been compared with analytical models and with finite element models. It has been observed that the finite element models coincide with the experimental results as long as the properties of the constituent materials of the sandwich panel are accurately known and the boundary conditions are suitably modeled. The analytical model also matches the finite element model when ideal supports are modelled.

Abstract

Homogenization procedures have been gaining more and more emphasis in the field of numerical analysis of composite materials. A homogenization procedure is based on the assumption that a set of equations or a representative element that can provide a response equivalent to the one provided by the actual material exists.

A numerical multiscale homogenization will be shown where the behavior of the whole composite is obtained by a micromechanical study of the material components and their interaction within of the composite microstructure through an RVE model. The proposed formulation uses a non-linear activation function in the structural scale and its task is to predict if a material point in the structure is in linear or non-linear range. Because of this, the developed strategy only solves the microscopic Boundary Value Problem using the RVE for the non-linear integration points found.

The procedure will be used in the nonlinear numerical simulaction of an eco-composite sanwich panel subjected to a four point bending test.

Abstract

Fused filament fabrication of foamed PLA enables lightweight structural parts with adjustable density and stiffness. This material expands during printing, making it ideal for functionally graded materials. It can serve as a sandwich core, enhancing lightweight properties. These panels can be a promising type of panel, as their behavior, such as vibracoustic, can be customized. However, their effectiveness in vibration attenuation remains unexplored. This study designs, manufactures, and tests 3D-printed foamed PLA sandwich panels with variable stiffness and density to improve vibroacoustic performance. The material’s Poisson’s ratio and elasticity modulus were characterized as a function of density, controlled by hot-end temperature and extrusion flow rate. A finite element model with spatially variable mechanical properties was developed for optimization. A genetic algorithm determined the optimal core properties to maximize the first two natural frequencies of a plate with one fixed edge and three free edges. The best designs were fabricated and tested, showing significant increment in the first two natural frequencies. This work advances the design and manufacturing of 3D-printed foamed PLA sandwich panels and contributes to high-performance, functionally graded components for enhanced vibroacoustic behavior.

Abstract

This abstract describes the weight optimization process followed by ALESTIS AEROSPACE in a secondary faring structure, designed and manufactured in composite material, focused in detail in the Belly Fairing structure of the A350 XWB A/C. The obective of this abstract is to enumerate and to decribe the weight optimization processes of this kind of structures, vieweing in detail following aspects: Optimum floatability definition in the joint between panels and structure Optimum design in sandwich panels Method to obtain out of plane loads for the joint between sandwich panel and structure Allowable determination for CFRP structure, based on finite element models correlated with mechanical tests It is also described in ths abstract the process followed to obtain test allowables and the methods developed to perform the weigth optimization in panels. Results obtained evidence that the Certification requirements are fulfilled for the complex design of a fairing such as Belly Fairing from A350XWB, manufactured with carbon fibre meterial with an optimum weigth.