Multilayer material comprising spider-web structures for energy dissipation

Abstract

A multilayer material (1) comprising in sequence (a) a base layer (2) consisting of a plurality of sublayers (5, 6), having spider web structures (7) made of polymeric fibres and / or mineral fibres immersed in a synthetic resin matrix; (b) a central layer (3) made of ceramic material; and (c) a front layer (4) composed of one or more sublayers, each of which comprises one or more spider web structures (7) made of polymeric fibres and / or mineral fibres immersed in a synthetic resin matrix.

Description

[0001] "MULTILAYER MATERIAL COMPRISING SPIDER-WEB STRUCTURES FOR ENERGY DISSIPATION"

[0002] Cross-Reference to Related Applications

[0003] This Patent Application claims priority from European Patent Application No . 24210738 . 1 filed on November 5 , 2024 and Italian Patent Application No . 102025000001779 filed on January 31 , 2025 , the entire disclosure of which is incorporated herein by reference .

[0004] Background

[0005] The present invention relates to a multilayer material comprising several spider-web structures made of fibres , to guarantee a high capacity of res istance to impact with a red fieuced weight .

[0006] In particular, the present invention has a preferred, but not exclusive , application in situations in which protection against Level 3 threats (NI J Standard) is required, such as , for example , land vehicles and aircraft .

[0007] Prior Art

[0008] As is known, over recent years , in sectors such as the aerospace , transport and civil engineering industries , there has been a strong need to have lightweight and high energy absorption materials .

[0009] In order to satis fy this need, sandwich, plate , honeycomb and foam structures have been developed, which have nonetheless proven not to be entirely satis factory .

[0010] In this regard, biomimetics , the science which studies and imitates the biological and biochemical processes of nature , is becoming a maj or source of inspiration for overcoming various technical problems . In particular, in the sector of research into materials that are resistant to impacts , the most promising solution inspired by nature appeared to be a spider web, designed to capture flying insects ( an example of resistance to impacts ) .

[0011] In fact , since a spider web is generally formed of spiral threads and radial threads , it is a typical natural example of a structure capable of trans ferring the impact energy confined within a small area (highly locali sed impact ) . While the spiral threads are mainly used to capture the prey, the radial threads dissipate the loads into the environment , from the centre of the web outwards .

[0012] Furthermore , over recent years , hybrid composite materials have been increasingly used in the aerospace , automobile , marine and energy industries for the construction of structures with unique mechanical properties . These composite materials are characterised by the presence of several types of fibres , contributing to obtaining the performance required through the combination of their properties .

[0013] Description of the Invention

[0014] The inventors of the present invention have obtained a multilayer material , the technical features of which satis fy the need to possess lightweight materials with a high capacity to dissipate energy .

[0015] The obj ect of the present invention is a multilayer material comprising in sequence ( a ) a base layer consisting o f a plurality of sublayers , having spider web structures made of polymeric fibres and / or mineral fibres immersed in a synthetic resin matrix ; (b ) a central layer made of ceramic material ; and ( c ) a front layer composed of one or more sublayers , each of which comprises one or more spider web structures made of polymeric fibres and / or mineral fibres immersed in a synthetic resin matrix .

[0016] Here and below, spider web structure means the combination of a plurality of radial fibres defining a radial structure and a plurality of transverse fibres , each of which intersects each of the radial fibres .

[0017] Preferably, said central layer is composed of a tessellation of a plurality of hexagonal plates made of ceramic material .

[0018] Preferably, said synthetic resin is a thermosetting resin, more preferably an epoxy resin .

[0019] Preferably, said base layer is composed of an alternation of sublayers comprising spider web structures made with polymeric fibres immersed in a synthetic resin matrix, and sublayers comprising spider web structures made with mineral fibres immersed in a synthetic resin matrix .

[0020] Preferably, said polymeric fibres are made of aramid .

[0021] Preferably, said mineral fibres are basalt fibres .

[0022] Preferably, the sublayers of said base layer are in a number between 20 and 30 .

[0023] Preferably, the sublayers of said front layer are in a number between 1 and 10 .

[0024] Brief Description of the Drawings

[0025] For a better understanding of the invention, an example of an embodiment thereo f is provided below, for illustrative purposes and non-limiting, with the assistance of the appended drawings , in which : Figure 1 is a schematic side view of a multilayer material according to the present invention;

[0026] Figure 2 is an exploded view, with parts removed for clarity, of a multilayer material according to the present invention;

[0027] - Figure 3 is a graph on which the results in terms of tension and displacement are shown;

[0028] - Figure 4 is an exempli fied model of a further arrangement of the spider web structures in a single sublayer .

[0029] Preferred Embodiment of the Invention

[0030] In Figures 1 and 2 , the number 1 indicates , in its entirety, a multilayer material according to the present invention .

[0031] The multilayer material 1 compri ses a base layer 2 , a central layer 3 and a front layer 4 .

[0032] The base layer 2 consists of a plurality of sublayers 5 and 6 . In particular, the sublayers 5 and 6 are arranged in an alternating sequence . The sublayers 5 comprise a spider web structure 7 made of basalt fibres immersed in an epoxy resin matrix, whereas the layers 6 comprise a spider web structure 7 made of aramid fibres immersed in an epoxy resin matrix .

[0033] The central layer 3 consists of a plurality of hexagonal ceramic plates 8 arranged with one another to form a tessellation . The function of the central layer 3 is to soften the tip of the bullet , reducing its penetrative capacity . These plates are commercially available in di f ferent dimensions .

[0034] The front layer 4 is composed of a sublayer 9 comprising a spider web structure 7 made of aramid fibres immersed in an epoxy resin matrix .

[0035] By way of example , a multilayer material according to the present invention was obtained which had the following structural requirements :

[0036] - the base layer 2 comprises twenty sublayers , alternating basalt fibres ( sublayers 5 ) and aramid fibres ( sublayers 6 ) in an epoxy resin matrix ; each sublayer 5 and 6 has the dimensions of a square with side equal to 300 mm and thickness equal to 0 . 6 mm .

[0037] - the central layer 3 is composed of ceramic plates of 10 mm in thickness ;

[0038] - the front layer comprises a layer of multilayer material in aramid fibres , immersed in a thermosetting resin matrix . The layer has the dimensions of a square with side equal to 300 mm and thickness equal to 0 . 6 mm .

[0039] The sublayers of the example described here above were obtained through extrusion of the fibres together with the epoxy resin . The sublayers thus obtained were superimposed and placed in an autoclave , subj ecting the layer to a suf ficient pressure for moulding . The same procedure was used to obtain the single sublayer 9 of the front layer 4 .

[0040] Once the base layer 2 had consol idated, the ceramic plates 8 were glued on to form the central layer 3 .

[0041] Lastly, the sublayer 9 was glued onto the central layer 3 to complete the multilayer material 1 in its entirety .

[0042] It is important to emphasise that a preferred embodiment provides for each sublayer comprising a configuration 10 consisting of several spider web structures , in which the respective load centres 11 are spaced apart from each other . In order to assist in understanding, an example of a configuration of the spider web structures with the load centres spaced is shown in Figure 4 . A comparison analysis in terms of tension and displacement is provided below, between a multilayer material according to the invention, in which the sublayers have fibres arranged in spider web structures , and a multilayer material that di f fers from the one of the invention exclusively in that it does not have fibres organised in a spider web structure .

[0043] Both the multilayer materials have a front layer formed of a single sublayer, a central layer and a base layer formed of twenty sublayers arranged in an alternation of polymeric fibres and mineral fibres . In both the multilayer materials , the thickness of the layers is the same .

[0044] The two multilayer materials di f fer exclusively in the arrangement of the fibres . In fact , whereas the multilayer material according to the invention comprises fibres organised in spider web structures , the multilayer material being compared comprises fibres arranged with one another in a parallel position, according to the orientations shown on Table IV .

[0045] For a correct assessment of the results indicated below, it must be considered that a weight of 1 . 49 Kg was calculated for the multilayer material according to the invention, whereas a weight of 2 . 76 Kg was calculated for the multilayer material being compared .

[0046] Calculation of the tension and the displacement was obtained considering the impact of a bullet of 7 . 62 mm in diameter, 51 mm in length and 150 g in weight and having a velocity of 847 ± 9 m / s .

[0047] The comparative analysis was performed using Hypermesh®

[0048] (Altair®) software , with Radioss® solver . The values of the mechanical properties of the materials considered in the definition of composite materials being compared are shown in Tables I - I T T . Table I - Aramid fibres in an epoxy resin matrix

[0049] Table I T - Mineral fibres in an epoxy resin matrix

[0050] Table I T T - Hexagonal ceramic plates

[0051] The structure of the multilayer material is shown in Table TV, on which the relative orientation of the fibres is indicated for each of the sublayers .

[0052] Table TV

[0053] The graphs of Figure 3 show the comparisons of the results in terms of tension and displacement obtained for the material being compared and for the material according to the invention . As confirmed by the graphs of Figure 3 , the tension and displacement values for the front layer of the multilayer material of the invention are higher than those of the multilayer material being compared . This means that most of the energy is already absorbed on the initial impact . In fact , the tension values for the base layer of the multilayer material of the invention are lower than those of the multilayer material being compared .

[0054] It is clear from the above that most of the impact energy of the bullet has been absorbed by the various layers and distributed radially . Another highly interesting feature for assessment of the comparison relates to the overall weight of the multilayer material . The spider web structure results in a weight that is around hal f the weight that can be obtained with the fibres organised as in the multilayer material being compared . This is a very important parameter (particularly in the space and aerospace industry) i f the intention is to design civil defence devices or aircraft .

[0055] The performances obtained in the simulations show a substantial beneficial ef fect given by the architecture of the fibres based on a spider web , because they are capable of absorbing and distributing impact energy ef fectively and ef ficiently .

[0056] In conclusion, the spider web structure has the advantage of dissipating the bullet ' s energy, resulting in a weight of the material that is signi ficantly lower, overall , than the weight of the materials in the prior art .

[0057] Furthermore , it should be noted that the presence of basalt fibres guarantees that the multilayer material is highly sustainable overall .

Claims

CLAIMS1. Multilayer material (1) comprising in sequence (a) a base layer (2) consisting of a plurality of sublayers (5, 6) , having spider web structures (7) made of polymeric fibres and / or mineral fibres immersed in a synthetic resin matrix; (b) a central layer (3) made of ceramic material; and (c) a front layer (4) composed of one or more sublayers, each of which comprises one or more spider web structures (7) made of polymeric fibres and / or mineral fibres immersed in a synthetic resin matrix .

2. Multilayer material according to claim 1, characterized in that said central layer (3) is composed of a tessellation of a plurality of hexagonal plates (8) made of ceramic material.

3. Multilayer material according to claim 1 or 2, characterized in that said synthetic resin is a thermosetting resin.

4. Multilayer material according to claim 3, characterized in that said thermosetting resin is an epoxy resin.

5. Multilayer material according to one of the preceding claims, characterized in that said base layer (2) is composed of an alternation of sublayers (6) comprising spider web structures made with polymeric fibres immersed in a synthetic resin matrix, and sublayers (5) comprising spider web structures made with mineral fibres immersed in a synthetic resin matrix.

6. Multilayer material according to one of the preceding claims, characterized in that said polymeric fibres are made of aramid.

7. Multilayer material according to one of the preceding claims, characterized in that said mineral fibres are basalt fibres.

8. Multilayer material according to any of the preceding claims, characterized in that the sublayers (5, 6) of said base layer (2) are in a number between 20 and 30.

9. Multilayer material according to any of the preceding claims, characterized in that the sublayers (9) of said front layer (4) are in a number between 1 and 10.

10. Multilayer material according to any of the preceding claims, characterized in that at least part of said sublayers (5, 6, 9) comprise a configuration (10) consisting of a plurality of spider web structures, in which the respective load centres (11) are spaced apart from each other.

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