DE102015204426A1 - Sandwich component or sandwich semifinished product - Google Patents

Abstract

A sandwich component or sandwich semifinished product having a layer structure (10, 10 ') of at least two fiber-reinforced cover layer elements (12, 16, 13, 17) having a synthetic resin matrix and at least one intermediate layer between two adjacent cover layer elements (12, 16; 13, 17 ), characterized in that at least one of the cover layer elements (12, 16, 13, 17) and / or the at least one core layer element (14, 15) channels (2, 2 '), the the respective cover layer element (12, 16, 13, 17) and / or the core layer element (14, 15) penetrate transversely.

Description

TECHNICAL AREA

The invention relates to a sandwich component or sandwich semifinished product according to the preamble of patent claim 1. It further relates to a method for producing such a sandwich component or sandwich semifinished product. Finally, the invention is also directed to the use of a sandwich component according to the invention as a kinetic energy absorbing crash element in a vehicle.

STATE OF THE ART

Conventional crash elements in vehicles, especially in motor vehicles, are made of plastically deformable materials, mostly metals, and convert the kinetic energy of the collision partners into deformation energy. In particular, in the event of side collisions, this transformation takes place by means of flexible rockers provided in the vehicle floor and in the vehicle side walls and vehicle doors.

The constant drive for reducing the energy consumption of a vehicle has resulted in vehicle metal components being increasingly replaced by fiber composite materials. Although fiber composites, such as carbon fiber composites (CFRP), may have a high flexural stiffness, especially if they are designed as a sandwich component. However, they have an extremely low ductility compared to metal materials. Energy absorbing crash elements, which are not made of metal, but of plastics, therefore convert the kinetic energy of the collision partners not in ductile deformation energy, but by material fragmentation in the free surface. This fragmentation process must be very effective in order to be able to convert as much energy as possible; This means that the smallest possible fragmentation of the components directly affected by the collision must take place. This is especially true for sandwich components, which are particularly advantageous for load-bearing vehicle parts, but also for large-scale components, such as vehicle floors, used because of their high bending stiffness.

The inventor has found that sandwich members having a layered structure of fiber reinforced cover sheet members and a core layer member interposed therebetween, when loaded with large momentum forces parallel to the bonding surfaces between the cover sheet members and the core layer member, tend to initially bulge before they fragment. In particular, a core layer element made of hard foam tends, when the individual layers are separated from one another in the region of their contact surfaces, to be folded between the peeling cover layer elements before it fragments. Such a folding process only consumes a very small part of the applied kinetic energy, and leads to a delay in the fragmentation process that accounts for the substantial portion of the kinetic energy. The effective reduction of kinetic energy is therefore delayed and too slow.

PRESENTATION OF THE INVENTION

The object of the present invention is to design a sand waking component or a sandwich semifinished product having a layer structure of at least two fiber-reinforced cover layer elements and at least one core layer element provided between two adjacent cover layer elements in such a way that more effective absorption of the impact energy by the impact layer occurs in the event of the occurrence of impact loads Sandwich component or sandwich semifinished product takes place. Furthermore, it is an object of the present invention to provide a method for producing such a sandwich component or sandwich semi-finished product.

The object directed to the sandwich component or sandwich semifinished product is achieved with the features of patent claim 1.

For this purpose, according to the invention, at least one of the cover layer elements and / or the at least one core layer element has channels which transversely penetrate the respective cover layer element and / or the core layer element.

ADVANTAGES

These channels, which run transversely, preferably at right angles, to the layer structure, form predetermined breaking points in the respective layer element, at which point the desired fragmentation can begin. The bulge or material folding observed in the test is thereby prevented, since the predetermined breaking points already provide fragmentation when small bending stresses occur.

Advantageous developments of the invention are specified in the subclaims.

Preferably, the cover layer elements on carbon fibers, which are embedded in the finished state of the sandwich component or the sandwich semi-finished product in the respective resin matrix. Carbon fibers not only have a high strength-to-weight ratio, but are also great for a highly effective energy-consuming fragmentation suitable.

It is particularly advantageous if the core layer element is formed from a hard foam material or from a softwood, such as balsa wood, or has such a hard foam material or softwood.

In an advantageous embodiment, the channels of through holes, preferably through holes, formed, which penetrate the respective cover layer element or the core layer element. The formation of the channels as the respective layer element transversely penetrating through holes has the advantage that the fragmentation irrespective of the direction in which the respective layer element bulges immediately sets in.

In certain applications, it is advantageous if the channels are formed only in the core layer element and if the openings of the channels are covered by the respective cover layer element. This variant is preferred if the sandwich component or sandwich semifinished product is exposed to external dust or moisture influences, since in this embodiment the cover layer elements close the channels and prevent the penetration of foreign bodies or moisture.

In other applications, the channels are formed in the core layer element and in at least one of the cover layer elements. In this variant, the channels provided in the cover layer element contribute to improved fragmentation. In an advantageous embodiment thereof, the channels are formed in both cover layer elements and in the core layer element.

Preferably, the channels are arranged at least in a region of the sandwich component or sandwich semifinished product at a uniform distance from one another. This leads to a uniform fragmentation and thus a controlled breakdown of kinetic energy in the event of a collision.

The spacing between adjacent channels may also be uniform but larger or smaller in other areas than in adjacent areas. This makes it possible to form regions with fragmentation which starts with a rapid rate of fragmentation, as a result of which it is possible to control the fracture behavior of the sandwich component or sandwich semifinished product and thus the intensity of the energy decomposition.

The directed to the method part of the object is achieved by a method having the features of claim 8.

• – Bereitstellen eines Schichtenaufbaus aus zumindest einem Kernschichtelement und zumindest zwei Deckschichtelementen, die Fasern, insbesondere Kohlefasern, und eine Kunstharzmatrix aufweisen und die auf zwei voneinander abgewandten Seiten des Kernschichtelements angeordnet sind oder werden;
• – Einbringen von Kanälen in zumindest eines der Deckschichtelemente und/oder in das zumindest eine Kernschichtelement, die das betreffende Deckschichtelement beziehungsweise das Kernschichtelement quer durchdringen, vor oder nach der Bildung des Schichtenaufbaus und vor oder nach dem Vernetzen und Aushärten der jeweiligen Kunstharzmatrix.

This inventive method for producing a sandwich component or a sandwich semi-finished product, in particular one according to the invention, is characterized by the steps

• - Providing a layer structure of at least one core layer element and at least two cover layer elements, the fibers, in particular carbon fibers, and a synthetic resin matrix and which are arranged on two opposite sides of the core layer element or are;
• - Introducing channels in at least one of the cover layer elements and / or in the at least one core layer element, which penetrate the respective cover layer element or the core layer element transversely, before or after the formation of the layer structure and before or after crosslinking and curing of the respective resin matrix.

The introduction of the channels can be done before the collapsing of the layer elements of the layer structure or after folding, depending on whether all the layer elements are to be penetrated by the channels or only individual layer elements. If the introduction of the channels takes place after the layer elements have been folded together, the channels thus penetrate all the layer elements of the layer structure, then the channels can be introduced before or after the crosslinking and curing of the respective synthetic resin matrix.

The introduction of the channels preferably takes place by needling of the respective layer element. In this way, a fast, machining is possible.

A particularly preferred application of the method according to the invention takes place in the production of vehicle components in which a sandwich component produced by the method according to the invention is used as the kinetic energy absorbing crash element of the vehicle. This application of the method according to the invention and the associated use of a sandwich component or sandwich semifinished product according to the invention combine the advantage of lightweight vehicle construction with a highly effective crash safety.

Preferred embodiments of the invention with additional design details and other advantages are described below with reference to the accompanying drawings and described.

BRIEF DESCRIPTION OF THE DRAWINGS

It shows:

1 a perspective view of a partially cut sandwich component according to the invention and

2 one of the illustration in 1 corresponding representation of an alternative embodiment of the sandwich component according to the invention.

PRESENTATION OF PREFERRED EMBODIMENTS

1 shows a perspective view of a sandwich component 1 with a layer structure 10 of two fiber-reinforced and a resin matrix having cover layer elements, a first cover layer element 12 and a second cover layer element 16 between which there is a core layer element consisting of rigid foam material or softwood (for example balsa wood) 14 located. The cover layer elements 12 . 16 For example, consist of a carbon fiber-resin composite material and are preferably as semi-finished fiber products, for example, as with matrix material (resin) preimpregnated fiber mats, on the core layer element 14 applied. The consistency of these pre-impregnated fiber mats, also referred to as "prepregs", is slightly tacky, leaving the topsheet elements 12 . 16 on the sides facing away from each other 14A . 14B the core layer element 14 be liable.

This layer construction 10 from the first cover layer element 12 , the core layer element 14 and the second cover layer element 16 has a variety of channels 2 forming through holes 20 . 22 on. These through holes 20 . 22 penetrate the first cover layer element 12 , the core layer element 14 and the second cover layer element 16 and lead on the one hand into the outer surface 12 ' of the first cover layer element 12 and on the other hand into the outer surface 16 ' of the second cover layer element.

In 1 it can be seen that the passageways 20 in a first region A of the sandwich component 1 are arranged at a uniform distance from each other. Also in a second area B of the sandwich component 1 have the through holes 22 an equal distance apart, but this distance is greater than the distance between the through holes 20 in area A. This distribution of through holes 20 . 22 causes the fragmentation in the area A with the smaller hole spacing faster and more effective, ie energy-consuming, takes place as in the area B with the larger hole spacing. This shows that the choice of the hole spacing can influence the fragmentation behavior.

At the in 2 illustrated alternative embodiment are as through holes 20 ' trained channels 2 ' only in the core layer element 15 intended. The two cover layer elements 13 . 17 are closed and cover the through holes 20 ' on both sides facing away from each other 15A . 15B the core layer element 15 off and close this. The improved fragmentation effect in this embodiment is on the core layer element 15 limited. The closed cover layer elements 13 . 17 prevent the entry of moisture and foreign bodies in the through holes 20 ' , Therefore, this embodiment can be used, for example, for floor panels of vehicles.

The sandwich components and sandwich semifinished products according to the invention can additionally have the layer structure 10 ' have transversely penetrating tensile force transmission elements, the tensile forces between the two cover layer elements 13 . 17 as described in Applicants' co-pending patent application (Applicant's Serial Number 28350).

The invention is not limited to the layer structure shown. Thus, instead of one core layer element, it is also possible to provide a plurality of core layer elements, between each of which an intermediate layer element is arranged, which preferably corresponds to the cover layer elements. The tensile force transmission elements then also extend through the entire layer structure.

The invention is not limited to the above embodiment, which merely serves to generally explain the essence of the invention. Within the scope of protection, the device according to the invention may also assume other than the above-described embodiments. In this case, the device may in particular have features that represent a combination of the respective individual features of the claims.

Reference signs in the claims, the description and the drawings are only for the better understanding of the invention and are not intended to limit the scope.

Claims (10)

Sandwich component or sandwich semifinished product with a layer structure ( 10 ; 10 ' ) of at least two fiber-reinforced and a resin matrix having cover layer elements ( 12 . 16 ; 13 . 17 ) and at least one between two adjacent cover layer elements ( 12 . 16 ; 13 . 17 ) core layer element ( 14 ; 15 ), characterized in that at least one of the cover layer elements ( 12 . 16 ; 13 . 17 ) and / or the at least one core layer element ( 14 ; 15 ) Channels ( 2 ; 2 ' ), which the respective cover layer element ( 12 . 16 ; 13 . 17 ) and / or the core layer element ( 14 ; 15 ) penetrate across. Sandwich component or sandwich semifinished product according to claim 1, characterized in that the cover layer elements ( 12 . 16 ; 13 . 17 ) Comprise carbon fibers which are embedded in the finished state of the sandwich component or sandwich semifinished product in the respective resin matrix. Sandwich component or sandwich semifinished product according to one of the preceding claims, characterized in that the core layer element ( 14 ; 15 ) consists of a rigid foam material or a softwood, preferably balsa wood, or has such. Sandwich component or sandwich semifinished product according to one of the preceding claims, characterized in that the channels ( 2 ; 2 ' ) of through holes ( 20 . 22 ; 20 ' ), preferably through-holes, are formed, which cover the respective cover layer element ( 12 . 16 ; 13 . 17 ) or core layer element ( 14 ; 15 penetrate). Sandwich component or sandwich semifinished product according to one of the preceding claims, characterized in that the channels ( 2 ' ) only in the core layer element ( 15 ) are formed and that the openings of the channels ( 2 ' ) of the respective cover layer element ( 13 . 17 ) are covered. Sandwich component or sandwich semi-finished product according to one of claims 1 to 4, characterized in that the channels ( 2 ) in the core layer element ( 14 ) and in at least one of the cover layer elements ( 12 . 16 ), preferably in both outer layer elements ( 12 . 16 ), are formed. Sandwich component or sandwich semifinished product according to one of the preceding claims, characterized in that the channels ( 2 ; 2 ' ) at least in a region of the sandwich component ( 1 ; 1' ) or sandwich semifinished product are arranged at a uniform distance from each other. Method for producing a sandwich component or sandwich semifinished product, in particular according to one of the preceding claims, characterized by the steps - providing a layer structure ( 10 ; 10 ' ) of at least one core layer element ( 14 ; 15 ) and at least two cover layer elements ( 12 . 16 ; 13 . 17 ), the fibers, in particular carbon fibers, and a synthetic resin matrix and on two opposite sides ( 14A . 14B ; 15A . 15B ) of the core layer element ( 14 ; 15 ) are or are arranged; - introducing channels ( 2 ; 2 ' ) in at least one of the cover layer elements ( 12 . 16 ) and / or in the at least one core layer element ( 14 ; 15 ), which the relevant cover layer element ( 12 . 16 ) or the core layer element ( 14 ; 15 ) penetrate transversely, before or after the formation of the layer structure ( 10 ; 10 ' ) and before or after crosslinking and curing of the respective resin matrix. Method according to claim 8, characterized in that the introduction of the channels ( 2 ; 2 ' ) by needling of the relevant layer element. Vehicle component with at least one sandwich component ( 1 ; 1' ) made by a method according to claim 8 or 9 for use as a kinetic energy absorbing crash element in the vehicle.

Images