with reference to the attached figure , a composite element for protection devices of parts of the human body is wholly indicated with 1 . the composite element 1 is provided for the realization of the inner portion — shock absorbing element — of a device for the protection of the human body parts , such as a helmet , a back protector , a shin protector , a forearm protector or similar devices to be used in sport activities . in particular , the composite element 1 can be associated to an outer shell , not shown in the figures , constituting the outer shell of a helmet or in general the outermost portion of a device for the protection of the human body . the composite element 1 comprises a matrix 2 and a reinforcing element 3 . the reinforcing element 3 is at least partially embedded in the matrix 2 . the matrix 2 is made with a material selected from the group comprising expanded polystyrene , polypropylene , polyurethane , ethylene - vinyl acetate ( eva ), nbr rubber and other lightweight polymers , elastomers , viscoelastic and viscoplastic polymers or similar materials . with reference to the embodiment illustrated in the figures , the reinforcing element 3 is partially embedded and positioned at the inner portion 4 of the matrix 2 . with reference to the matrix 2 , the expression “ inner portion ” refers to the portion of the matrix 2 that in use is placed in proximity or in direct contact with the body of a user . with reference to the matrix 2 , the expression “ external portion ” refers to the portion of the matrix 2 that in use faces externally with respect to the portion of the human body to which the composite element 1 is applied . according to a further version of the present invention , not shown in the figures , the reinforcing element 3 is at least partially embedded in correspondence of the external portion of the matrix 2 . still , according to a further version of the present invention , not shown in the figures , the reinforcing element 3 is wholly embedded in the central portion or in the inner portion or in the outer portion of the matrix 2 . the reinforcing element 3 has a substantially flat - type crosslinked structure , showing a top surface 6 and a bottom surface 7 . according to the relative position of the reinforcing element 3 respect to the matrix 2 with reference to the embodiment illustrated in the attached figures , by way of a non - limiting example , the reinforcing element 3 has at least one opening 5 . according to a version of the present invention , the opening 5 is of the through type . with reference to the structure of the reinforcing element 3 shown in fig2 , the latter is provided with a plurality of hexagonal through openings 5 . however , further shapes of the at least one opening 5 , not shown in the figures , comprising at least one opening of circular and / or elliptical and / or square and / or any polygonal shape without departing from the scope of protection of the present invention are possible . with reference to the sectional view of the reinforcing element 3 shown in fig3 , the at least one opening 5 presents a substantially frusto - conical section . in particular , the at least one opening 5 at the bottom surface 7 of the reinforcing element 3 has a section narrower than that at the top surface 6 . when the reinforcing element 3 is partially embedded at the inner portion or at the outer portion of the matrix 2 , the top surface 6 of the reinforcing element 3 is preferably provided facing towards the inner portion or at the outer portion of the matrix 2 . the at least one opening 5 is complementary to the matrix 2 and vice versa . the frusto - conical configuration of the at least one opening 5 ensures high performance of the composite element 1 , with particular reference to the resistance against objects penetration . furthermore , the particular shape of the reinforcement element 3 ensures a high ability to distribute the stresses induced by an impact within the matrix 2 , as better described hereinafter . the at least one opening 5 presents a substantially vertical axis 8 . the vertical axis 8 defines a direction with respect to which the side walls 9 of the at least one opening 5 are inclined . if the at least one opening 5 presents , in plan view , a substantially circular shape , the inclination of the side wall 9 confers a truncated - cone shape to the inner section of the at least one opening 5 . according to another version , not shown in the figures , the at least one opening 5 can present a quadrangular shape , in plan view . therefore , the inclination of the side walls 9 with respect to the axis 8 confers to the inner section of the at least one opening 5 a truncated pyramid shape . the configuration of the at least one opening 5 determines an undercut 10 between the matrix 2 and the reinforcing element 3 . this undercut 10 determines , in turn , a mechanical constraint between the matrix 2 and the reinforcing element 3 , preventing the latter to detach from the matrix 2 itself in steady state or following an impact . the reinforcing element 3 is made of an elastic material capable of deforming under the action of an external traction or compression force , and to return to its original shape when the force is no longer applied . according to a further version of the present invention , the reinforcing element 3 is plastically deformable . the reinforcing element 3 is selected from the group comprising ethylene - vinyl acetate ( eva ), nbr rubber , polyurethane , polystyrene , polypropylene , and other lightweight viscoelastic or viscoplastic polymers and elastomers or similar materials . according to a version of the present invention , unlike the reinforcing mesh element used in the known art previously described , the reinforcing element 3 is elastically deformable along any direction . thanks to its elasticity , the reinforcing element 3 can be easily conformed to adapt it to the various geometries of the protection devices of parts of the human body that are to be produced . the reinforcing element 3 presents a substantially cross - linked structure that allows to transmit the stress of an impact occurring on a restricted area of the composite element 1 and to transmit it to a larger area within the matrix 2 . in this way , since the impact energy is dissipated on a larger area within the matrix 2 , the stress transmitted to the body of a user is effectively reduced , thus increasing the efficiency of protection device itself . the matrix 2 is made with a thermoplastic or thermoset type material that in the initial stage is of liquid or foam nature , or in pre - expanded beads with surface that bond with each other at higher temperatures . the matrix 2 , for example , can be co - injected into a mold in which the reinforcing element 3 has been previously placed . the matrix 2 has a stiffness greater than that of the reinforcing element 3 . an interface between the matrix 2 and the reinforcing element 3 is determined , at which bonds of chemical , physical and mechanical type are established . the chemical and physical bonds determine high cohesion between the matrix 2 and the reinforcing element 3 , thus allowing between the components constituting the composite element 1 the effectively transmission and dissipation of the energy that is released during an impact . the matrix 2 and the reinforcing element 3 may belong to the same or to different group of materials . the chemical and physical bonds that are established at the interface between the matrix 2 and the reinforcing element 3 determine a continuity of the composite material 1 , avoiding the presence of voids or defects that may reduce the ability of the composite material 1 to effectively dissipate the collision energy . the mechanical bonds between the matrix 2 and the reinforcing element 3 are due to the at least one undercut 10 at the at least one opening 5 . the at least one undercut 10 ensures a high cohesion between the matrix 2 and the reinforcing element 3 itself , that are complementary one to each other , increasing the effect of adhesion of the chemical and physical bonds . with reference to the embodiment illustrated in fig6 , as a result of an external impact acting against the composite element 1 , both the matrix 2 and the reinforcing element 3 are subject to compressive stress , indicated by the vertical arrows 11 . the reinforcing element 3 during the compression phase is compressed along the vertical direction and simultaneously widens in the horizontal direction as shown by the horizontal arrows 12 . the matrix 2 hinders the horizontal deformation of the reinforcing element 3 at the undercut 10 . the reinforcing element 3 during an impact undergoes an elastic deformation , while the matrix 2 undergoes a plastic type deformation due to the action of the external impact force and by the action of the reinforcing element 3 at the undercut 10 . however , a composite element 1 comprising a matrix 2 and a reinforcing element 3 made with materials with similar elastic , plastic and viscoelastic properties but of different stiffness and / or density that will provide different interface behaviors is possible . due to the different behavior of the materials constituting the matrix 2 and the reinforcing element 3 it may happen that the physical and chemical bonds at the interface between these components may be altered . however , the presence of a least one undercut 10 ensures a high compactness and mechanical cohesion between the matrix 2 and the reinforcing element 3 , also in the case in which the chemical and / or physical bonds are weakened or broken . the reinforcing element 3 , indeed , is elastically flexible and able to distribute the energy of an impact over a large interface of the matrix 2 . the increase of plastic deformation of the matrix 2 induced by the horizontal elastic deformation of the reinforcing element 3 increases both surface and volume impact energy absorption efficiency of the matrix 2 . by the elastic behavior , the reinforcing element 3 does not cause concentrated efforts that may damage the matrix 2 reducing its integrity and , therefore , the ability to isolate the portion of the human body against which the protection device is placed . regardless of the fact that an impact insists on a concentrated area or a wide area of a composite element 1 , the reinforcing element 3 allows to effectively dissipate the energy of the impact , distributing the same in an efficiently manner within the matrix 2 , thus overcoming the drawbacks of the known art . according to another version of the present invention , the matrix 2 can be elastically , viscoelastically or viscoplastically deformable , while the reinforcing element 3 can be plastically deformable . according to a further version of the present invention , both the matrix 2 and the reinforcing element 3 are elastically or viscoelastically or viscoplastically deformable . according to a further version of the present invention , both the matrix 2 and the reinforcing element 3 are plastically deformable . the composite element 1 , according to the present invention , allows to effectively dissipate the energy that is transmitted to the parts of the human body during an impact . the reinforcing element 3 and the matrix 2 are lightweight and therefore they do not contribute to significantly increase the weight of the composite element 1 , thereby allowing the body weight content of a protection device of parts of human . thus a protection device made up with the composite element 1 is lightweight and comfortable to wear . the reinforcing element 3 may be partially or fully embedded within the matrix 2 , at its inner portion 4 that , during the use , it is foreseen to be placed in direct or indirect contact with the portion of the human body to be protected , and / or at central portion and / or at external portion that in use it is not in contact with the portion of the human body to protect . the present invention also relates to a method for the realisation of composite element 1 for protection devices of parts of the human body , to be used during sports and / or leisure activities . the method , according to the present invention , involves the realisation of a composite element 1 with high performance , high impact energy absorption and resistance against the penetration of objects , through a process of co - molding , within an economic solution . providing at least one mold ; providing within the mold a reinforcing element ( 3 ) comprising at least one opening ( 5 ); introducing a material forming the matrix ( 2 ) inside the mold ; at least partially embed the reinforcing element ( 3 ) in the matrix ( 2 ), determining at least one undercut ( 10 ) between the reinforcing element ( 3 ) and the matrix ( 2 ) in correspondence of the at least one opening ( 5 ). the material of the matrix 2 can be initially of liquid or foam state , or in a form of pre - expanded beads . according to one version of the present invention , the matrix 2 is co - molded together with the reinforcing element 3 inside a same mold . after the co - molding step it is expected until the complete solidification of the matrix 2 occurs . after the solidification of the matrix 2 , the mold can be opened and the composite element 1 thus obtained can be removed . the features of the composite element 1 may be modified varying the position of the reinforcing element 3 with respect to the matrix 2 , i . e . by placing the reinforcing element 3 in correspondence of the outer , inner or middle portion of the matrix 2 . moreover , it is possible to use reinforcing elements 3 comprising at least two openings 5 , each one provided with a different shape and size from each other , in order to vary the deformability and the mechanical behavior of the reinforcing element 3 itself . in the case that the composite element 1 is realized through a co - molding process , it is possible to use co - molding molds of the traditional type , thus reducing the costs of production of the composite element 1 , as it is not required the fitting of new molds . the present invention has been described according to preferred embodiments , but equivalent variants can be devised without departing from the scope of protection offered by the following claims .
a composite element for the realization of protection devices of parts of the human body includes a matrix , a reinforcing element , at least partially embedded in the matrix , wherein the reinforcing element has at least one opening shaped so as to define an undercut between the matrix and the reinforcing element , such undercut being suitable for determining a mechanical constraint between the matrix and the reinforcement element .