ES2589036A1 - Structural panel of stiffness and variable resistance and its manufacturing process (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

The present invention describes a structural panel of stiffness and variable resistance and its manufacturing process. The panel results from the stacking of two or more selectively deformable sub-panels of lower thickness fig. 3 or fig. 4. These subpanels can be overlapped in different numbers, thicknesses and directions to obtain a final structure or panel fig. 6 with a thickness and certain mechanical properties. The set of superimposed subpanels can be manufactured by means of a 3d printing process, and the resulting gaps as a consequence of the geometry of each subpanel can be filled with a filling material, this process can be carried out by immersion in a liquid subjected to a curing process later. (Machine-translation by Google Translate, not legally binding)

Description

STRUCTURAL PANEL OF RIGIDITY AND VARIABLE RESISTANCE AND ITS MANUFACTURING PROCESS 5 SECTOR OF THE TECHNIQUE 10 Materials and manufacturing processes of structural panels. BACKGROUND OF THE INVENTION For many years now, composite materials have been known in the manufacture of structures of different types. Specifically, if we talk about composite materials consisting of fibers or fiber bundles embedded in a thermosetting or thermoplastic resin matrix, their use has different advantages over conventional isotropic materials, precisely because of the possibility that these materials offer properties. structural differentiated according to the direction considered, varying the amount of fibers oriented in each direction, since it is the fibers in these materials that constitute the main resistant element. 20 These composite materials made as stacked of fabrics composed of fibers and embedded in resin matrix have the ability to be designed with directional mechanical properties, but by their very nature they are eminently rigid materials in all directions. There are applications, however, in which it would be very useful to have a material with directional flexibility. This led to the birth of the concept of Selectively Oeformable Structures (ESO). Under this concept have been described (Amiryants et aL, Se / ectively Deformable 30 Structures for Design of Adaptive Wing Smart Elements, 27th International Congress of the Aeronautical Sciences, 2010) panels with a special geometry that allows them to show directional stiffness properties, at at the same time they can present flexibility against deformation outside their plane. This material can be easily deformed in a "useful" direction, maintaining the stiffness in the other 35 directions thus providing control and shape of the assigned structure under applied external loads. The main component of an ESO is a cell of 2

variable geometry load, the cell comprising a thin wall reinforced with rigid central and peripheral elements, as well as deformable support elastic components. The stiffness in compression / tension is insignificant due to the special order of the elements within the cell while the stiffness in bending, torsion and shear is maintained at assigned finite levels. Combined in chains, cells can form adaptive frameworks of any structure.

The selectively deformable structures described so far consist, therefore, in basically panel-shaped structures, designed with a geometry adapted to the final elastic properties that are to be achieved for that particular structure. No material is available in the current state of the art that can serve as a more or less standard basis for designing structures of elastic properties to measure, as is done with the mechanical properties of pieces of composite material from fabrics made with fibers.

EXPLANATION OF THE INVENTION

The present invention falls within the field of materials and processes for structural panels. It is a three-dimensional structure that comprises a series of highly directional sub-panels of superimposed overlapping and arranged in different orientations to obtain different stiffnesses and resistances for the resulting assembly depending on the combination of sub-panels chosen.

Starting from the known concept of Selectively Oeformable Structures (ESO), the present invention consists of a structure whose deformability and rigidity can be custom designed by superimposing different ESO panels in different spatial orientations, as needed.

The advantages of the panel object of the invention are:

The establishment of different panel definition parameters through the use of different stacking sequences of the highly directional stiffness sub-panels, allowing a simple change of the mechanical properties in terms of stiffness and strength. The wide scope of the use of the resulting panels whose configuration is adapted to the load levels in each application. For example, if we want a panel that has greater strength and rigidity under axial load conditions, there will be a majority of sub-panels at 0 °, while if the dominant internal load is cut, most subpanels will have +/- orientation. 45 °

The object of the present invention is the manufacture of the structure characterized by the superposition of ESO panels from any material by means of a 3D printing process, such as additive manufacturing.

It is also another object of the present invention to fill the gaps of the resulting material with a preferably flexible filling material, such as an elastomeric resin compatible with the skeleton material.

BRIEF DESCRIPTION OF THE DRAWINGS

A series of drawings that help to better understand the invention and that expressly relate to an embodiment of said invention which is presented as a non-limiting example thereof is described very briefly below.

FIG 1 shows a schematic view of a highly directional elementary cell.

FIG 2 shows a scheme of another type of elementary cell with its main geometric parameters.

FIG 3 shows a highly directional sub-panel based on the elementary cells shown in FIG 1.

FIG 4 shows a highly directional sub-panel based on the elementary cells shown in FIG 2.

FIG 5 shows a diagram of the panels oriented in the four directions, 0 °, 90 °, + 45 °, -45 °.

FIG 6 shows a result panel of stacking 7 sub-panels in different directions.

PREFERRED EMBODIMENT OF THE INVENTION

In a preferred embodiment of this invention, the final structure results from a process of additive manufacturing or 3D printing that allows different subpanels constituted by directional cells to be manufactured in a single set.

Directional cells can be based on different geometries that share the same property of presenting a direction with greater rigidity and structural strength, than their perpendicular direction. As an example, a schematic view of a highly directional elementary cell based on straight segments is shown in FIG 1 and another configuration based on curved sections in FIG 2. The geometry of this elementary cell can therefore present different geometries, thicknesses, radii, angles but always with the common element of presenting a mechanically privileged direction with respect to the perpendicular.

From the repetition of the elementary cells, the sub-panels in FIG 3 and 4 result based on the modules included in FIG 1 and 2 respectively.

Defined an address as a reference, address 0 °, the orientation we give to the sub-panels, together with the thickness "t;" of each sub-panel, results in different mechanical characteristics in rigidity and strength of the panel as a whole. For example, FIG 5 shows sub-panels oriented in four different directions 0 °, + 45 °, -45 ° Y90 ° with respect to the direction taken as a reference.

To form the final panel, the sub-panels that we want to use to configure the desired mechanical characteristics are superimposed on top of each other. As an example, FIG 6 shows a panel resulting from stacking 7 sub-panels in different directions; in this case the addresses of each sub-panel are 0/90/45/0 / + 45/90/0. The thickness of the resulting panel, "t", is the sum of the thicknesses of the sub-panels, t = Li ~~ ti "n" being the number of sub-panels.

In a preferred embodiment of the invention, said panel is configured as solid in a Computer-Aided-Design (CAD) system following the following scheme:

Design in CAD solid geometric elements of different configurations that meet the requirement of presenting greater rigidity in one direction than in the perpendicular.

Then design in CAD sub-panels based on the repetition of the previous geometric elements and that consequently present highly directional stiffness and resistance.

Finally, design in CAD a panel that results from stacking according to certain directions, such as the 0 °, + 45 °, -45 ° and 90 ° directions, of sub-panels that have highly directional stiffness and resistance.

The resulting panel designed as a solid CAD model can be manufactured from any material by a 3D printing process such as additive manufacturing with commercially available devices. The result is a single piece that presents the gaps originated by its own constitution. These holes can be filled with some material, either to give a better surface finish, waterproof properties, or to provide additional mechanical characteristics to the final assembly. The filling may be necessary to achieve smooth and continuous sealed loading surfaces, for example, for aeronautical applications. This filling material may consist of an elastomer chemically compatible with the base material of the skeleton, which could be provided in liquid form, by immersion of the " skeleton "formed by the superposition of subpanels, followed by a curing process of said elastomeric material forming a joint with the skeleton.

Claims (5)

1. Variable stiffness and strength structural panel comprising the superposition of 2 or more selectively deformable sub-panels 5 oriented differently to achieve the result of objective mechanical properties.

2.

Structural panel according to claim 1, based on 3D printing with metallic or non-metallic materials.

3.

Structural panel according to claims 1 or 2, characterized by filling the holes in the cells of each subpanel with a filler material.

Four.

Structural panel according to claim 3, characterized in that the filling of

15 The gaps in the panels are made by immersing said panels in a fluid material chemically compatible with the base material of the skeleton and which is cured in solidarity with it. 5. Structural panel according to claims 3 or 4 characterized in that the filling material is an elastomeric material. and FIG 1 p p ... e FIG2 FIG3 FIG4 FIG 5