Abstract:
A connection is between a monolithic metal component and a continuous-fiber reinforced laminate component wherein the metal component and the laminate component are joined at the ends thereof. A method allows for the production of the connection between the monolithic metal component and the continuous-fiber reinforced laminate component.

Description:
BACKGROUND 
       [0001]    The present invention relates to a connection between a monolithic metal component and a continuous fiber reinforced laminate component and a method for production of the same. 
         [0002]    The classic aluminum CFRP (carbon fiber reinforced plastic) joint connection predominantly used today is the rivet and bolt joint. For reasons of corrosion protection a CFRP laminate is to be provided in a supplementary manufacturing step with a separation layer of glass fiber. Advantages of a rivet connection lie in the high degree of experience and automation capacity in the assembly. Having regard to material utilization, however, a rivet connection constitutes an unsuitable joining method for fiber composite materials. The elements to be transferred, namely the fibers, are interrupted in a bore for a rivet. In addition, with an increasing anisotropy level (E∥/E⊥) there are very high notch stresses. In order to compensate, adaptations in the layer orientation and additional reinforcing layers are necessary in order to reduce the notch stress level with a then quasi-isotropic structure. 
         [0003]    A further disadvantage in rivet connection is that the boring in the CFRP necessary for this brings with it a considerable wear of tools due to the heterogeneous material structure. Indeed, due to the necessary tolerances in the production of the rivet connection, both joining partners must often be bored through in a single work step. Particularly in case of CFRP with for example high tensile steels, however, there is no suitable wear protection for boring tools which protects both materials. 
         [0004]    Adhesion technology has established itself as an alternative or as a supplement to the rivet connection of fiber composite structures. Example applications are found, inter alia, in the field of rail vehicle construction, the motor car industry, ship building and the construction of wind power plants. While the analysis of shear and peel stresses in adhesive connections is being researched, adhesion in aeronautical applications can, however, only be carried out and gain acceptance in a limited way due to the absence of a possibility of non-destructive testing. The adhesion of structural parts is additionally essentially limited to shell-form geometries and leads to large joining zones due to the necessary area of the joining partners. 
         [0005]    Both in rivet or bolt connection and in adhesive connection a joining of overlapping materials arises. This has the disadvantage of a high construction height. 
       SUMMARY 
       [0006]    It is thus an object of the invention to provide a connection between a monolithic metal component and a continuous fiber reinforced laminate component which has a smaller construction height with similar or even improved mechanical properties. 
         [0007]    A connection between a monolithic metal component and a continuous fiber reinforced laminate component, comprises a first zone, in which metal wires or a metal lattice or a perforated plate is/are bonded through thermal joining or through a molding process to an end face of the metal component parallel to said end face, a second zone with a laminate layer structure, in which layers of the laminate component which extend from an end face of the laminate component are layered alternately with fibers, whereby the fibers comprise loops at one end which are fixed to the metal wires or to the metal lattice or to the perforated plate, and a transition zone with a laminate layer structure, in which the layers of the laminate component which extend from the end face of the laminate component are layered alternately with free ends of the fibers of the second zone, forming a transition. 
         [0008]    In some embodiments of the invention, the laminate component can be a CFRP component. The monolithic metal component can also be made of aluminum. The thermal joining can in some embodiments comprise welding or soldering, and it is contemplated that the molding process in some embodiments will comprise casting. According to some contemplated embodiments of the invention, the fibers are carbon fibers, and the metal wires, the metal lattice or the perforated plate comprise titanium. 
         [0009]    It is contemplated that the metal wires or the metal lattice or the perforated plate can be formed so that the fibers are not in contact with the metal component to help reduce or avoid corrosion. According to a particular embodiment of the invention, the metal component is a metal shell and the laminate component is a CFRP sandwich panel. 
         [0010]    Some contemplated invention embodiments include a connection between a monolithic metal component and a continuous fiber reinforced laminate component, comprising a zone in which a metal laminate is bonded on the end face through thermal joining or a molding process to an end face of the metal component, and a transition zone with a metal fiber laminate layer structure, in which layers of the laminate component which extend from an end face of the laminate component are layered alternately with ends of the metal layers of the metal laminate, forming a transition. 
         [0011]    In such embodiments, it is contemplated the laminate component can be a CFRP component, and the monolithic metal component can further be made of aluminum. According to some particular embodiments of the invention, the metal layers of the metal laminate consist of metal foils or sheets, which can also comprise titanium. Such embodiments can also incorporate thermal joining such as welding or soldering and further include a molding process that comprises casting. Such embodiments of the invention utilize a metal component that is a metal shell and a laminate component is a CFRP sandwich panel. 
         [0012]    Furthermore, it is contemplated that the present invention provides a method for producing a connection utilizing fiber loops that are produced by means of a textile production process, preferably a tailored fiber placement process. The second zone can be soaked with a matrix simultaneously with a plastic injection process for the production of the laminate component. 
         [0013]    The metal laminate can also be produced by means of a modified tape laying device. It can therefore be provided that the metal layers of the metal laminate are provided before production by means of such a tape laying device with an adhesive layer or simultaneously with the production with an adhesive film. 
         [0014]    The invention recognizes that by providing load-bearing incorporated fiber elements or through integrated metal layers which are in turn associated with a force carrying metal composite, an end face joining of a monolithic metal component and a continuous fiber reinforced laminate component is facilitated, allowing for a reduction in construction height. The present invention provides integral material connections for fiber composite materials with metals which are characterized by a small construction space, low weight and the prevention of corrosion of the metal when using carbon fibers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Further features and advantages of the invention follow from the attached claims and the following description, in which multiple embodiments are explained individually in detail by reference to the schematic drawings, in which: 
           [0016]      FIG. 1  depicts a top view (left) and a longitudinal sectional view (right) of a connection between a monolithic metal component and a continuous fiber reinforced laminate component according to one embodiment of the invention; 
           [0017]      FIG. 2  depicts a top view (left) and a longitudinal sectional view (right) of a connection between a monolithic metal component and a continuous fiber reinforced laminate component according to a first particular embodiment of the invention; and 
           [0018]      FIG. 3  depicts a longitudinal sectional view of a connection between a CFRP sandwich panel and a metal component. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  shows a connection  10  between a monolithic metal component  12  made of aluminum and a continuous fiber reinforced laminate component  14  existing in the form of a CFRP component. The connection  10  comprises a first zone  16 , in which a metal lattice is bonded by welding to an end face  20  of the metal component  12  parallel to said end face, a second zone  22  with a laminate layer structure, in which layers  24 ,  26 ,  28 ,  30 ,  32  and  33  of the laminate component  14  which extend from an end face  34  of the laminate component  14  are layered alternately with fibers  36 ,  38 ,  40 ,  42  and  44 , whereby the fibers  36 ,  38 ,  40 ,  42  and  44  comprise at one end loops (fiber loops)  46 ,  48 ,  50 ,  52  and  54  which are fixed to the metal lattice  18 , and a transition zone  56  with a laminate layer structure, in which the layers  24 ,  26 ,  28 ,  30  and  32  of the laminate component  14  which extend from the end face  34  of the laminate component, are layered alternately with free ends  58 ,  60 ,  62 ,  64  and  66  of the fibers  36 ,  38 ,  40 ,  42  and  44  of the second zone  22 , forming a transition. “Forming a transition” is intended to mean in this case that a part of the free ends, namely the free ends  60  and  64 , do not extend as far as the end face  34  of the laminate component  14 , but that they are already previously relieved by layers  27  and  31 . 
         [0020]    It is contemplated that the fibers  36  to  44  can be carbon fibers. In addition the metal lattice  18  is formed so that the fibers  36 ,  38 ,  40 ,  42  and  44  are not in contact with the metal component  12 . 
         [0021]    The fiber loops  46 ,  48 ,  50 ,  52  and  54  pass the forces to be transferred for the connection  10  to the metal lattice  18 . This can consist, for example, of titanium. In addition, the fiber loops  46  to  54  can be produced with a textile production process such as, for example, the tailored fiber placement process. In a small space, multiple shape-locking connections are produced with the metal lattice  18 . This joint region can be soaked with a matrix simultaneously with a plastic injection process for the remaining laminate component  14  made of CFRP and can thus also transfer compressive forces. 
         [0022]    The cross-section of the fiber loops  46 ,  48 ,  50 ,  52  and  54  can be adapted to the deformation behavior of the fiber bundles in order to fully utilize the material potential. Depending on specific application requirements, it is contemplated that perforated plates, individual wires, metal loops or eyes, or like structures can also be used instead of the metal lattice  18 . As an alternative to the fiber loops  46  to  54  shown, textile meshes or also other textile bonding is/are possible. 
         [0023]    In terms of construction, the connection can be dimensioned via the coordination of the individual elements and their geometries in such a way that having regard to light construction a local over-dimensioning is avoided. The type of failure and the origin of failure can be set and reliably executed. 
         [0024]    With the connection described above (joint connection) very high loads can be transferred. The invention is superior to previous configurations in light construction having regard to construction space, weight, reliability and manufacturability. The construction space is clearly reduced in comparison with an adhesive connection as the necessary contact areas are relatively small. 
         [0025]    Through the targeted use of different metals in the different zones, a corrosion between CFRP and, for example, aluminum can be avoided. 
         [0026]    The second zone  22  can be produced by means of textile processes and thus be realized very quickly and economically. The inventive connection is thus clearly superior to previous connections for laminates and is suitable also for new applications, for example, CFRP components in motor car construction. Such connection also facilitates the end face joining of, for example, CFRP sandwich panels with metal shells. This is shown schematically in  FIG. 3 . 
         [0027]      FIG. 2  shows a connection  70  between a monolithic metal component  72  and a continuous fiber reinforced laminate component  74  according to a particular embodiment of the invention. The metal component  72  comprises aluminum and the laminate component  74  is a CFRP component. The connection  70  comprises a zone  76 , in which a metal laminate  78  is bonded on the end face through welding to an end face  80  of the metal component  72 , and a transition zone  82  with a metal fiber laminate layer structure, in which layers  84 ,  86 ,  88 ,  90  and  92  of the laminate component, which extend from an end face  94  of the laminate component  74  are layered alternately with ends  96 ,  98 ,  100 ,  102 ,  104 ,  106 ,  108 ,  110 ,  112 ,  114  and  116  of the metal layers  118 ,  120 ,  122 ,  124 ,  126 ,  128 ,  130 ,  132 ,  134 ,  136  and  138  of the metal laminate  78 , forming a transition. 
         [0028]    The metal layers  118  to  138  can comprise metal foils made of titanium. In the transition zone  82  the continuous fiber reinforced laminate component  74  made of CFRP transfers parts of the load to the metal foils. In addition the layers  84  to  92  run out and are replaced in teams of layers by further metal foils. The mechanical loads can thus continually go from one material to another. 
         [0029]    In the zone  76  all layers  84  to  92  are replaced by metal foils and form here a metal plastic laminate. In addition the metal foils transfer in said zone  76  the forces to be transferred for the connection to the metal component  72 . The joint area extends virtually over the entire cross-section of the zone  76 . 
         [0030]    The metal laminate  78  can be deposited in an automated way with modified tape layers, as used in CFRP production in prepreg technology. For this, either the metal foils used are previously provided with an adhesive layer or an adhesive film is applied in parallel in the lamination process. 
         [0031]    By means of the layer-wise running-out of the metal layers or metal foils in the transition zone  82 , a large connection area of the laminate component  74  to the metal component  72  can be achieved. By means of the large transition region, stress peaks can be avoided, as otherwise arise in material transitions. 
         [0032]    In constructive terms, a connection can be dimensioned by means of coordination of the individual elements and their geometries in such a way that, having regard to light construction, a local over-dimensioning is avoided. The type of failure and the origin of the failure can be set and reliably executed. 
         [0033]    An end face joining with metal joining partners is constructively useful (central load introduction, small construction space, aerodynamic areas). 
         [0034]    Through tape laying devices the connection can be produced quickly and economically. The connection is thus clearly superior to current connections for laminate and is also suitable for new applications such as, for example, CFRP components in motor car construction. The integration of fiber composite laminates in existing metal structures is clearly simplified. 
         [0035]      FIG. 3  schematically depicts an inventive connection  160  between a CFRP sandwich panel  140  comprising two CFRP layers  142  and  144 , between which a foam core  146  is sandwiched, and a metal component  148  made of aluminum, which is realized in the same way as the connection shown in  FIG. 2 . The sandwich panel  140  merely does not comprise—unlike the laminate component  74  made of CFRP in FIG.  2 —a planar end face but instead a conically extending end face  150 . 
         [0036]    The features of the invention disclosed in the above description, in the drawings and in the claims can be essential both individually and in any combinations for the realization of the invention in its various embodiments.