FR3158132A1 - METAL AND COMPOSITE TUBE - Google Patents

Abstract

The invention relates to a metal and composite tube (4) comprising a first tube (6) made of metal material, a second tube made of composite material, and a core (8). The core (8) is located within the first tube (6) and the second tube. The core (8) is made of a composite material. The core (8) comprises branches (80) extending between, on the one hand, a center of the metal and composite tube (4) and, on the other hand, at least one of the first tube (6) and the second tube. (Figure 1)

Description

METAL AND COMPOSITE TUBE Technical field of the invention

The invention relates to the field of manufacturing structural tubes, in particular for vehicles. More specifically, it relates to a metal and composite tube. In particular, the metal and composite tube is part of a chassis of the vehicle and is designed to protect people inside the vehicle from injury in the event of an accident. The vehicle is, for example, a light aircraft such as a tourist plane or an ultra-light motorized aircraft, also known as a "ULM".

State of the prior art

The frames of current light land and air vehicles are generally made of metal. These metallic materials are often heavy. For legal and environmental reasons, the mass of vehicles is tending to decrease, primarily to limit the pollution generated by these vehicles.

Materials lighter than metals and their alloys are being developed and used. Composite materials are known for their low mass and mechanical strength. However, composite materials are rarely used in the chassis of land or air motor vehicles due to the low maximum plastic deformation of these materials and the risk of sudden breakage of these materials, generating fragments that are dangerous for people nearby in the event of an accident.

Safety requirements for people on board vehicles are also becoming more stringent, particularly to ensure that the vehicle effectively protects these people in the event of an accident. Vehicle safety requirements are also difficult to reconcile with vehicle mass reduction requirements, which tend to reduce the maximum amount of energy that the vehicle can absorb in the event of an accident without injuring the people on board.

Metallic and composite tubes have recently been developed for automotive and aeronautical use, as illustrated for example by the IEE Access publication, “Crashworthiness Analysis and Design of Metal/CFRP hybrid structures under lateral loading,” authored by Guohua Zhu, Xuan Zhao, Peilong Shi, and Qiang Yu, which was published on May 30, 2019. These metallic and composite tubes have made it possible to increase the mechanical strength of tubes, while limiting the mass and size of the tubes.

There is a need to further increase the mechanical strength of a tube, while limiting the mass and bulk of the tube. In particular, there is a need to improve the safety of a driver, a pilot and/or passengers inside a vehicle in the event of an accident, while limiting the mass and bulk of the vehicle.

The invention aims to remedy all or part of the drawbacks of the state of the art mentioned above.

In this regard, the invention relates to a metal and composite tube, in particular for a land and/or air vehicle. The metal and composite tube comprises a first tube made of metal material and a second tube made of composite material.

According to the invention, the metal and composite tube comprises a core located inside the first tube and the second tube. The core is made of a composite material. The core comprises branches extending between, on the one hand, a center of the metal and composite tube and, on the other hand, at least one of the first tube and the second tube.

Thanks to the metal and composite tube according to the invention, the mechanical strength of a tube is increased, while limiting the mass and size of the tube. The safety of a pilot, a driver and/or passengers is notably improved, while limiting the mass and size of a vehicle comprising the metal and composite tube. The manufacture of the metal and composite tube is relatively easy. In particular, the core is relatively easy to manufacture.

In particular, the safety of people inside the vehicle is improved, since the metal and composite tube absorbs a large amount of energy during a vehicle accident, while deforming in a controlled manner, avoiding injury to people during the deformation of the tube. The metal material of the first tube and the composite material of the second tube and the core provide maximum energy absorption that is greater than the sum of the maximum energy absorbed by the metal material on the one hand and that absorbed by each composite material on the other hand, while controlling the deformation of the metal and composite tube.

The metallic material of the first tube protects the composite material of the second tube and/or the core, in particular from radiation, mechanical shocks and humidity. The metallic material deforms gradually by deforming plastically until it breaks. By deforming more gradually, the metallic material helps to control the deformation of the composite material by limiting the risk of sudden breakage of the composite material which could, for example, injure people in the vehicle.

The composite material has high resistance to deformation and impact, especially compared to the metallic material. Cracks in the composite material are accompanied by plastic deformation of the metallic material. The composite material allows for a reduction in the mass and size of the tubes.

According to a particular embodiment, the first tube made of metallic material is located around the second tube made of composite material while being located outside the second tube. The second tube is located around the core while being located outside the core.

According to another embodiment feature, the metal and composite tube is cylindrical with a circular cross-section. The first tube is cylindrical with a circular cross-section. The second tube is cylindrical with a circular cross-section.

According to a particular embodiment, the composite material of the second tube and/or the core comprises a matrix and reinforcing fibers. The matrix comprises at least one resin chosen from at least one polyepoxide, one polyester and one polyetherketone. The reinforcing fibers comprise at least one element chosen from carbon fibers, glass fibers and aramid fibers.

According to a particular embodiment, the core is made of the same composite material as the composite material of the second tube. According to another particular embodiment, the composite material of the second tube and/or the core comprises a polyepoxide and carbon fibers.

According to another embodiment feature, the first tube made of metallic material is made of a metallic material which comprises aluminum and/or titanium. Preferably, the first tube comprises a titanium alloy.

According to another embodiment feature, each branch extends radially from a center of the metal and composite tube to at least one of the first tube and the second tube.

According to another embodiment feature, the branches are distributed angularly uniformly relative to the first tube and/or the second tube.

According to a particular embodiment, each branch comprises a flat wall. According to a particular embodiment, each branch extends substantially over the entire length of the second tube in a longitudinal direction of the metal and composite tube.

The invention also relates to a method for manufacturing a metal and composite tube as defined above. The manufacturing method comprises a step of manufacturing the core during which composite material is placed at least partially around a core. The core is removed after manufacturing the core. The manufacturing method comprises a step of manufacturing the second tube inside the first tube. The manufacturing method comprises a step of inserting the core inside the first tube and the second tube.

According to a particular embodiment, the core is substantially a right prism. According to another particular embodiment, the core comprises at least one substantially triangular transverse surface.

According to another embodiment feature, the core is manufactured around a set of cores which includes lateral cores. Preferably, the lateral cores are held in position by a holding system. Preferably, the number of lateral cores in the set of cores is equal to the number of branches of the core.

According to a particular embodiment, the holding system comprises a first end core, a second end core and holding rods. The first end core and the second end core are inserted around the rods. The rods extend longitudinally parallel to the longitudinal direction of the core.

According to a particular embodiment, during the core manufacturing step, a sheet of composite material is slid between cores which are held against the sheet of composite material.

According to another embodiment, the second tube is manufactured around a central insert by impregnation of fibers with a matrix of the composite material. The central insert presses the composite material against the first tube.

The invention finally relates to an aircraft comprising a tubular chassis, the chassis comprising a set of tubes which comprises metal and composite tubes as defined above. Preferably, the aircraft is a tourist aircraft or an ultra light motorized aircraft, also known as “ULM”.

brief description of the figures

• laFIG. 1est une représentation schématique partielle en perspective d’un tube métallique et composite selon un premier mode de réalisation de l’invention ;
• laFIG. 2est une représentation en coupe transversale du tube métallique et composite selon le premier mode de réalisation ;
• laFIG. 3est une représentation en perspective d’une âme et d’un deuxième tube du tube métallique et composite selon le premier mode de réalisation ;
• laFIG. 4illustre le procédé de fabrication du tube métallique et composite selon le premier mode de réalisation ;
• les figures 5a, 5b, 5c, 5d, 5e illustrent des étapes de procédé de fabrication de l’âme du tube métallique et composite selon le premier mode de réalisation ;
• laFIG. 6est une représentation en perspective d’un ensemble de noyaux prismatiques triangulaires pour fabriquer l’âme du tube métallique et composite selon le premier mode de réalisation ;
• laFIG. 7illustre l’imprégnation de fibres par la matrice pour fabriquer le matériau composite ;
• laFIG. 8est une représentation en perspective de la fixation du deuxième tube au premier tube, lors de la fabrication du tube métallique et composite selon le premier mode de réalisation ;
• laFIG. 9est une représentation en perspective d’un châssis pour aéronef comprenant un ensemble de tubes métalliques et composites selon le premier mode de réalisation ;
• laFIG. 10est une représentation en vue de côté d’un aéronef comprenant un châssis formé par un ensemble de tubes métalliques et composites selon le premier mode de réalisation ;

The present invention will be better understood upon reading the description of exemplary embodiments, with reference to the appended drawings in which:

• there FIG. 1 is a partial schematic representation in perspective of a metallic and composite tube according to a first embodiment of the invention;
• there FIG. 2 is a cross-sectional representation of the metal and composite tube according to the first embodiment;
• there FIG. 3 is a perspective representation of a core and a second tube of the metallic and composite tube according to the first embodiment;
• there FIG. 4 illustrates the manufacturing process of the metal and composite tube according to the first embodiment;
• Figures 5a, 5b, 5c, 5d, 5e illustrate steps of the manufacturing process of the core of the metal and composite tube according to the first embodiment;
• there FIG. 6 is a perspective representation of a set of triangular prismatic cores for manufacturing the core of the metallic and composite tube according to the first embodiment;
• there FIG. 7 illustrates the impregnation of fibers by the matrix to manufacture the composite material;
• there FIG. 8 is a perspective representation of the attachment of the second tube to the first tube, during the manufacture of the metallic and composite tube according to the first embodiment;
• there FIG. 9 is a perspective representation of an aircraft chassis comprising a set of metal and composite tubes according to the first embodiment;
• there FIG. 10 is a side view representation of an aircraft comprising a chassis formed by a set of metal and composite tubes according to the first embodiment;

For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

DETAILED description of an embodiment

There FIG. 1 represents a metal and composite tube 4, for example for a land and/or air vehicle 1 such as a light aircraft like the one shown in FIG. 10 . The metal and composite tube 4 comprises a first tube 6 made of metal material, a second tube 7 made of composite material, and a core 8 which is also made of composite material. The metal and composite tube 4 is in particular a structural tube. In particular, the metal and composite tubes 4 serve to mechanically protect people inside a set of these metal and composite tubes 4, while limiting the mass and size of the set of metal and composite tubes 4.

In this document and in the absence of any specification to the contrary, an axial direction is a direction which is parallel to the longitudinal direction X-X of the metal and composite tube 4. A radial direction is a direction which is locally perpendicular to the axial direction. An orthoradial direction is a direction which is locally perpendicular to the axial direction and to the radial direction. A transverse plane is a plane which is orthogonal to the longitudinal direction X-X of the metal and composite tube 4. A transverse plane is formed by a radial direction and an orthoradial direction.

In the embodiment shown, the metal and composite tube 4 is cylindrical with a circular cross-section around the longitudinal direction X-X of the metal and composite tube 4. The first tube 6 is cylindrical with a circular cross-section being centered around the longitudinal direction X-X of the metal and composite tube 4. The second tube 7 is cylindrical with a circular cross-section being centered around the longitudinal direction X-X of the metal and composite tube 4.

The first tube 6 is made of a metallic material which comprises steel, aluminum and/or titanium. The first tube 6 envelops the second tube 7 made of composite material while being located outside the second tube 7. The first tube 6 radially delimits the metallic and composite tube 4 towards the outside.

When vehicle 1 is a motorized road vehicle, the metallic material includes, for example, steel. When vehicle 1 is an air vehicle, the metallic material is lighter and includes, for example, aluminum or titanium.

In each of the embodiments shown, the metallic material is a titanium alloy. The titanium alloy is for example a Grade 9 TiAL3V2.5 titanium alloy which is widely used in competition bicycle frames and aeronautical structures and which is manufactured by the company STAINLESS or any other titanium alloy which presents a good compromise between the mechanical strength and the density of the metallic material.

The second tube 7 is made of composite material. The second tube 7 surrounds the core 8 while being located outside the core 8. The second tube 7 is located radially between the core 8 and the first tube 6. The second tube 7 is preferably of a shape substantially identical to that of the first tube 6, to facilitate mechanical contact between the second tube 7 and the first tube 6.

The composite material of the second tube 7 and/or the core 8 comprises a matrix and reinforcing fibers. The matrix comprises at least one resin selected from at least one polyepoxide, one polyester and one polyetherketone. The reinforcing fibers comprise at least one element selected from carbon fibers, glass fibers and aramid fibers. Aramid fibers are also known by the trade name “kevlar”.

In the embodiment shown, the composite material comprises a polyepoxide and carbon fibers. The polyepoxide is for example the product known under the trade name “SR 1500” from the company Sicomin. The carbon fibers are for example fibers known under the name “C193 Sergé Carbone 193 g/m ² 3K” from the company Sicomin. In the embodiment shown, the second tube 7 and the core 8 are made from the same composite material.

The core 8 has a general star shape. The core 8 is centered around the longitudinal axis X-X of the metal and composite tube 4. The core 8 is located inside the first tube 6 and the second tube 7. The core 8 comprises the center 41 and branches 80 which each extend between the center 41 and the second tube 7. The center 41 of the core 8 is the center of the metal and composite tube 4. The core 8 serves to improve the mechanical strength of the metal and composite tube 4, while limiting the mass and size of the metal and composite tube 4.

More specifically, each branch 80 comprises a flat wall 82. Each branch 80 extends radially from a center of the metal and composite tube 4 to the second tube 7. The branches 80 diverge from the center 41 of the metal and composite tube 4. The branches 80 are distributed angularly uniformly relative to the first tube 6 and to the second tube 7. Each branch 80 extends substantially over the entire length of the second tube 7 in a longitudinal direction X-X of the metal and composite tube. The branches 80 are preferably two by two identical. Generally, the number of branches 80 of the core 8 is variable.

In the embodiment shown, the core 8 comprises five branches. The branches 80 have the general shape of a rectangular parallelepiped. The thickness e of each of the branches 80 is, for example, substantially equal to the thickness of the wall of the second tube 7 and/or the first tube 6.

There FIG. 4 illustrates the manufacturing method 100 of the metal and composite tube 4. The method 100 comprises a step 101 of manufacturing the first tube 6, a step 200 of manufacturing the second tube 7, a step 300 of manufacturing the core 8, and a step 106 of inserting the core 8 inside the second tube 7. The order of the manufacturing steps 101, 200, 300 may vary, but the step 200 of manufacturing the second tube takes place after the step 101 of manufacturing the first tube. The step 106 of inserting the core 8 inside the second tube 7 occurs after the manufacturing steps 101, 200, 300.

The first tube 6 is for example a commercial tube. The step 101 of manufacturing the first tube is generally a preliminary step which is implemented by people other than those who implement the other steps of the manufacturing method 100.

Figures 7 and 8 illustrate step 200 of manufacturing the second tube 7. During step 200 of manufacturing the second tube 7, the second tube 7 is manufactured layer by layer around a central insert 11 by impregnation 201 of fibers by the matrix of the composite material. The fibers are for example in the form of sheets which are wound one after the other around a central insert 11, after impregnation 201 of the fibers by the matrix. The central insert 11 is inflated by a pressurized fluid, for example air, to press the composite material of the second tube 7 against the first tube 6, during a step 203 of pressing the composite material against the first tube 6. The composite material is for example heated when it is pressed by the central insert 11 against the first tube 6. The heating of the composite material promotes in particular the polymerization and drying of the matrix of the composite material, in particular when the matrix is a thermosetting resin such as a polyepoxide. The insert 11 is then depressurized and removed from the second tube 7, during a step 205 of depressurization and removal of the insert 11, after the composite material of the second tube 7 has been fixed by adhesion to the first tube 6.

The central insert 11 has the same shape as that of the first tube 6 and that of the second tube 7. The central insert 11 is configured to swell under the effect of a fluid and to press the composite material against the first tube 6. By pressing the composite material of the second tube 7 against the first tube 6 during drying of the composite material, the central insert 11 allows satisfactory adhesion of the second tube 7 to the first tube 6.

Figures 5a to 5e illustrate the step 300 of manufacturing the core 8. Generally, during the step 300 of manufacturing the core 8, composite material is placed at least partially around at least one core 12, 14, 16, this core 12, 14, 16 being removed after the manufacturing of the core 8. More precisely, during the step 300 of manufacturing the core 8, a sheet of composite material is slid between lateral cores 12 which are held against the sheet of composite material by a holding system 18.

With reference to Figure 5a, the manufacture 300 of the core starts with a step 301 of inserting a first end core 14 and a second end core 16 around holding rods 83 which extend longitudinally parallel to the longitudinal direction X-X of the metal and composite tube 4. With reference to Figure 5b, the manufacture 300 of the core comprises the preparation 303 of the composite material of the core 8, by impregnating reinforcing sheets with a matrix of the composite material. The step 303 of preparing the composite material can optionally take place before or during the step 301 of inserting the first end core 14 and the second end core 16 around holding rods 83. With reference to Figure 5c, the manufacturing 300 of the core continues with the placement 305 of the composite material between lateral cores 12. During the placement 305 of the composite material, sheets of composite material are slid between the lateral cores 12 and the end cores 14, 16. With reference to Figure 5d, the manufacturing 300 of the core continues with a step 307 of holding and compressing the lateral cores 12 against the composite material. With reference to Figure 5e, the manufacturing 300 of the core ends with the removal 309 of the cores 12, 14, 16 and possibly by cutting the part of the rods 83 which protrudes from the core 8.

The core 8 is manufactured around a set 10 of cores which comprises the side cores 12 and the end cores 14, 16. The number of side cores of the set 10 of cores is equal to the number of branches 80 of the core 8. The set of cores 10 comprises two end cores 14, 16.

The shape of each lateral core 12 is likely to vary depending on the number of branches. With reference to figures 5a and 5e, each lateral core 12 has a general shape of a right prism, having in particular an external lateral surface in the form of a cylindrical segment of circular section. In the embodiment shown with five branches 80, the cores have a substantially triangular cross section. Each lateral core 12 is for example crossed by a central rod to facilitate handling. The lateral cores 12 are held in position by a holding system 18.

The holding system 18 comprises the first end core 14, the second end core 16, the holding rods 83, an elastic holding element 17 and radial compression elements 19. The holding system 18 is configured to hold the composite material in position relative to the set 10 of cores during drying of the composite material of the core 8. In particular, the holding system 18 is configured to hold the lateral cores 12 in position relative to each other.

With joint reference to Figures 5a and 5e, the end cores 14, 16 are for example located at the ends of the core 8 in the axial direction. The first end core 14 and the second end core 16 have substantially the same shape. The first end core 14 and the second end core 16 each have substantially the same shape as the core, at least in cross-section of the core 8 and in cross-section of the end cores 14, 16. The end cores 14, 16 are configured to maintain the relative position of the holding rods 83.

The holding rods 83 are made of composite material. Most preferably, the holding rods 83 are made of the same composite material as that of the core 8. The rods 83 pass axially through the core 8 during drying of the composite material. At least a portion of the rods 83 preferably forms part of the core 8, once the core is manufactured. The holding rods 83 and the end cores 14, 16 serve as support for the side cores 12 and the composite material before it has dried.

The elastic holding element 17 is for example an elastic which promotes the holding in position of the holding rods 83 relative to each other. Each radial compression element 19 takes for example the form of a strap which is tightened around the lateral cores 12, to compress the lateral cores 12 against the composite material. The holding system 18 comprises for example at least two radial compression elements 19 which are axially spaced from each other.

During step 106 of inserting the core 8 inside the second tube 7, the core 8 is for example inserted by force inside the second tube 7. The core 8 is for example rigidly secured to the second tube 7, by being compressed inside the second tube 7.

There FIG. 9 represents a chassis 2 for a land or air vehicle 1, which is a tubular chassis 2 and which comprises metal and composite tubes 4. The chassis 2 comprises vertices 20 and a set of tubes which comprises the metal and composite tubes 4. The chassis 2 serves to protect the people inside the aircraft in the event of an accident, passively, i.e. without control and without intervention by a pilot. The vertices 20 rigidly connect the metal and composite tubes 4 together. The metal and composite tubes 4 which are furthest from a passenger compartment of the vehicle 1 are configured to deform more quickly to absorb as much energy as possible sufficiently far from the people in the passenger compartment, in the event of an accident. The metal and composite tubes 4 which are closest to the passenger compartment are those which have the highest mechanical resistance, to protect the people inside the passenger compartment.

There FIG. 10 represents a light aircraft 1 such as a tourist aircraft or an ultra-light powered aircraft which is known as a microlight. The aircraft 1 comprises a frame 2, wings 3, wheels 5 and a propeller 6. The metal and composite tubes 4 of the frame 2 are particularly useful in the case of a light aircraft 1 in which the safety of persons on board is clearly likely to be improved.

Thanks to the metal and composite tube 4 according to the invention, the mechanical resistance of the tube 4 is very high, while limiting the mass and size of the tube 4. The safety of a pilot, a driver and/or passengers is improved, while limiting the mass and size of a vehicle 1 comprising the metal and composite tube 4. The manufacture of the metal and composite tube 4 is relatively easy. In particular, the core 8 is relatively easy to manufacture.

The safety of people inside the vehicle 1 is improved, since the metal and composite tube 4 absorbs a large amount of energy during an accident of the vehicle 1, while deforming in a controlled manner, avoiding injury to people during the deformation of the tube 4. The metal material of the first tube 6 and the composite material of the second tube 7 and the core 8 provide a maximum energy absorption which is greater than the sum of the maximum energy which is absorbed by the metal material on the one hand and by that which is absorbed by each composite material on the other hand, while controlling the deformation of the metal and composite tube 4.

The metallic material of the first tube 6 protects the composite material of the second tube 7 and/or the core 8, in particular from radiation, mechanical shocks and humidity. By deforming more gradually, the metallic material helps to control the deformation of the composite material by limiting the risk of sudden breakage of the composite material which would, for example, be likely to injure people in the vehicle 1.

The composite material has high resistance to deformation and impact, especially compared to the metallic material. The appearance of cracks in the composite material is accompanied by the plastic deformation of the metallic material. The number of dangerous fragments formed by deterioration of the composite material is very low. The composite material reduces the mass and bulk of the tubes compared to tubes of the same dimensions made entirely of metallic material.

Of course, various modifications can be made by those skilled in the art to the invention which has just been described without departing from the scope of the disclosure of the invention.

Alternatively, the second tube 7 envelops the first tube 6, being located outside the first tube 6. In this case, the core 8 is inside the first tube 6.

Alternatively, the cross-section of the first tube 6 and/or the second tube 7 is polygonal. For example, the first tube 6 and the second tube 7 are of square cross-section.

Alternatively, the composite material of the second tube 7 is distinct from that of the core 8.

Alternatively, the branches 80 of the core 8 are fixed to each other. Additionally or alternatively, the thickness of each of the branches 80 is greater than the thickness of the wall of the second tube 7.

Alternatively, the metal and composite tube 4 is a structural tube for a use other than a land or air vehicle 1, for example for a tent peg.

Alternatively, the vehicle 1 is a motorized land vehicle 1, such as an automobile. Alternatively, the land vehicle 1 is a non-motorized vehicle such as a bicycle.

The shape of each lateral core 12 is variable and depends on the number of branches 80.

Alternatively, the core assembly 10 is without an end core 14, 16. Alternatively, the holding system 18 is without an elastic holding element 17 and/or a radial compression element 19.

Claims (15)

Metallic and composite tube (4), in particular for a land and/or air vehicle (1), comprising a first tube (6) made of metallic material and a second tube (7) made of composite material, characterized in that the metallic and composite tube (4) comprises a core (8) located inside the first tube (6) and the second tube (7), the core (8) being made of a composite material, the core (8) comprising branches (80) extending between on the one hand a center of the metallic and composite tube (4) and on the other hand at least one of the first tube (6) and the second tube (7). Metallic and composite tube (4) according to any one of the preceding claims, in which the first tube (6) of metallic material envelops the second tube (7) of composite material while being located outside the second tube (7), the second tube (7) envelops the core (8) while being located outside the core (8). A metal and composite tube (4) according to any one of the preceding claims, wherein the metal and composite tube (4) is cylindrical with a circular cross-section, the first tube (6) is cylindrical with a circular cross-section, the second tube (7) is cylindrical with a circular cross-section. Metal and composite tube (4) according to any one of the preceding claims, in which the composite material of the second tube (7) and/or of the core (8) comprises a matrix and reinforcing fibers, the matrix comprising at least one resin chosen from at least one polyepoxide, one polyester and one polyetherketone, the reinforcing fibers comprising at least one element chosen from carbon fibers, glass fibers and aramid fibers. Metal and composite tube (4) according to the preceding claim, in which the core (8) is in the same composite material as the composite material of the second tube (7), and/or in which the composite material comprises a polyepoxide and carbon fibers. A metal and composite tube (4) according to any preceding claim, wherein the first tube (6) is made of a metal material which comprises aluminium and/or titanium, preferably a titanium alloy. A metal and composite tube (4) according to any preceding claim, wherein each branch (80) extends radially from a center of the metal and composite tube (4) to at least one of the first tube (6) and the second tube (7), and/or wherein the branches (80) are angularly distributed uniformly relative to the first tube (6) and/or the second tube (7). Metal and composite tube (4) according to any one of the preceding claims, in which each branch (80) comprises a flat wall (82), and/or in which each branch (80) extends substantially over the entire length of the second tube (7) in a longitudinal direction (X-X) of the metal and composite tube. Method for manufacturing a metal and composite tube (4) according to any one of the preceding claims, comprising a step (300) of manufacturing the core (8) during which composite material is placed at least partially around a core (12), the core (12) being removed after manufacturing the core (8), a step (200) of manufacturing the second tube (7) inside the first tube (6), and a step (106) of inserting the core (8) inside the first tube (6) and the second tube (7). Method for manufacturing a metal and composite tube (4) according to the preceding claim, in which the core (12) is substantially a right prism and/or in which the core (12) comprises at least one substantially triangular transverse surface. Method for manufacturing a metal and composite tube (4) according to any one of the preceding claims 9 and 10, in which the core (8) is manufactured around a set (10) of cores which comprises lateral cores (12), the lateral cores (12) preferably being held in position by a holding system (18), the number of lateral cores of the set (10) of cores being in particular equal to the number of branches (80) of the core (8). Method for manufacturing a metal and composite tube (4) according to the preceding claim, in which the holding system (18) comprises a first end core (14), a second end core (16) and holding rods (83), the first end core (14) and the second end core (16) being inserted around the rods (83), the rods (83) extending longitudinally parallel to the longitudinal direction (X-X) of the core. Method for manufacturing a metal and composite tube (4) according to any one of the preceding claims 9 to 12, in which during the step (300) of manufacturing the core (8), a sheet of composite material is slid between cores (12) which are then held against the sheet of composite material. Method of manufacturing a metal and composite tube (4) according to any one of the preceding claims 9 to 13, in which the second tube (7) is manufactured around a central insert (11) by impregnation of fibers with a matrix of the composite material, the central insert (11) pressing the composite material against the first tube (6). Aircraft (1) comprising a chassis (2) comprising a set of tubes which comprises metal and composite tubes (4) according to any one of claims 1 to 8.