CN112406200A

CN112406200A - Elastic sandwich component

Info

Publication number: CN112406200A
Application number: CN202010839813.5A
Authority: CN
Inventors: 莱因哈德·哈菲琳娜
Original assignee: Lai YinhadeHafeilinna
Current assignee: Lai YinhadeHafeilinna
Priority date: 2019-08-20
Filing date: 2020-08-19
Publication date: 2021-02-26
Also published as: DE102019122333B4; DE102019122333A1

Abstract

The invention relates to a sandwich component (100) having a first cover layer (101), a second cover layer (102) and a core layer (103). Since the core layer (103) is arranged between the first cover layer (101) and the second cover layer (102), the first cover layer (101), the core layer (103) and the second cover layer (102) form a sandwich structure. The core layer (103) has a shear stiffness greater than 5 MPa. The core layer (103) is configured to be recoverable such that at least 95% of an original thickness of the core layer (103) is recoverable when the thickness of the core layer (103) is reduced by 20% of the original thickness due to a compressive force.

Description

Elastic sandwich component

Technical Field

The invention relates to a sandwich component having elastic properties and a method for producing a sandwich component.

Background

Composite materials are used in many applications, such as automotive, aerospace, sporting goods or housing parts of equipment, to make lightweight components. Thus, for example, vehicle housings, luggage compartments or cabins of rail trains or aircraft and housings of equipment, i.e. high impact forces due to the impact of items of luggage, due to vandalism or falling on the ground, can cause permanent damage to the products. For example, for a base element in the interior of an aircraft, it must be able to pass a drop test of beverage bottles or other items, where the weight of the drop must not cause damage from a particular height. The bottom must accordingly be of robust constructional design. In this case, it may be constructed in a sandwich type to satisfy light building performance. However, such composites are generally not impact resistant.

A sandwich composite material is known from DE 20119367U1, which has two metal sheets that are fixed to a fiber core and are also separated by the fiber core. The core consists of a porous network with metal fibers. DE 20201922U discloses a sandwich material having a honeycomb core made of paper and a thickness of 8mm to 100mm, which has a coating of aluminum sheet or glass-fiber-reinforced plastic on both sides.

However, in previous sandwich composite materials there is the risk that when the cover layers are strongly elastically deformed, the core layer is also subsequently plastically deformed, which leads to permanent damage to the component.

Honeycomb cores made of paper, fibrous material or aluminum are commonly used as the core material. Compact or foamed thermoplastics are also often used. Under load and deformation, plastic or other irreversible deformation occurs after the initial elastic deformation. In the event of impact loading, such inelastic deformation can, for example, lead to bulging or other irreversible damage. Therefore, the product does not have sufficient robustness to withstand such impact loads.

Disclosure of Invention

The present invention is directed to a lightweight structural member that resists sudden external impact forces.

The invention is finally achieved by a sandwich component and a method for producing a sandwich component.

According to a first aspect of the invention, a sandwich component is described. The sandwich component has a first tensilely rigid cover layer, a second tensilely rigid cover layer and a core layer. The core layer is arranged between the first cover layer and the second cover layer in such a way that the first cover layer, the core layer and the second cover layer form a sandwich structure. The core layer has a shear stiffness greater than 5 MPa. The core layer is configured to be recoverable such that at least 95% of the original thickness of the core layer is recoverable when the thickness of the core layer is reduced by 20% of the original thickness due to a compressive force. Thus, the compression set (DVR) of the core layer is less than 5%.

Exemplary embodimentsDetailed description of the invention

For example, the cover layer and the core layer are configured to be elastic. The core layer here has an elasticity in the compression direction of at least 1%, in particular at least 5% or 25%, which is largely reversible, at least 90%, in particular 95%, of the deformation being recovered by the elastic action. For a deformation of 1%, in particular less than 5% or 25%, the compression set is less than 10%. The core layer is configured to be recoverable such that at least 95% of the original thickness of the core layer is recoverable when the thickness of the core layer is reduced by 20% of the original thickness due to a compressive force. In more specific exemplary embodiments, the core layer is configured to be recoverable such that at least 95% (equivalent to 100%) of the original thickness of the core layer is recoverable when the thickness of the core layer is reduced by 40%, and particularly by 50%, of the original thickness due to the compressive force. The original geometry is thereby established to a large extent, so that no further deformations are present to the extent of visibility or to the extent of an effect on the function. To the extent that it is visible or has an effect on function, no bulging or damage occurs. This means that the elastic recovery is achieved by deformation due to local impact loads, so that no or hardly visible residual deformation is maintained. As such, the product can resist these impact loads. The first cover layer (and/or the second cover layer) is designed in such a way that its core layer can be elastically and reversibly deformed in the event of an (in particular punctiform) elastic deformation of the first cover layer.

Compression set (DVR) is a measure of how an elastomer performs under long-term, constant compression set and subsequent relaxation. The compression set (DVR, compression set) is measured at constant deformation according to DIN 53517 or DIN ISO 815 or ASTM D395. This represents a deformed portion of the test material. To determine DVR, for example, a cylindrical test body is compressed, for example, by 25% and stored for a certain time at a certain temperature. The temperature and medium (mainly air, also including oil and other working fluids) of the compression set test depend on the material to be tested, its intended use and the test structure (for example, for EPDM profiles at 70 ℃ for 24 hours under building protection). 30 minutes after unloading, the height is again measured at room temperature and the permanent set is determined therefrom.

A compression set of 0% indicates that the body has fully recovered its original thickness, and a compression set of 100% indicates that the body has fully deformed and not recovered during the test.

The calculation is made according to the following formula: DVR (%) - (L0-L2)/(L0-L1) × 100%

Wherein:

DVR-compression set expressed in percent

L0 ═ height of test body before test

L1-height of test body during test (distance block)

L2 ═ the height of the test body after the test.

Another function of the invention is to provide a method for manufacturing a sandwich component as described above. According to the method, the core layer is arranged between the first cover layer and the second cover layer such that the first cover layer, the core layer and the second cover layer form a sandwich structure.

The cover layer is made of a tensile-rigid material, for example a high-strength material. The cover layer serves to absorb tensile and compressive forces in the direction of the surface. The core layer serves to absorb shear forces and, as described in the present invention, to additionally reversibly absorb compressive forces in the thickness direction.

In an exemplary embodiment, the core layer has a material composition made of a cross-linked polymer material. The core layer thus forms an elastic core layer.

In another exemplary embodiment, the core layer has a material composition made of a polyurethane elastomer.

The elastic core layer is composed, for example, of an elastomer or a mixture of different elastomers, for example of Natural Rubber (NR), acrylonitrile butadiene rubber (NBR), Styrene Butadiene Rubber (SBR), chloroprene rubber, acrylonitrile butadiene rubber (NBR), a mixture of Butadiene Rubber (BR) and EPDM, and, for example, of various auxiliaries and additives, as well as fillers and reinforcing materials. The core layer may also be composed of a silicone elastomer or EPDM. Likewise, the core layer can also consist of a thermoplastic which is rendered elastic by subsequent crosslinking of the polymer chains. In particular, according to another exemplary embodiment, the core layer may have a material composition made of silicone rubber.

According to another exemplary embodiment, the density of the core layer is less than 800kg/m³In particular less than 500kg/m³In particular less than 250kg/m³. For this purpose, the core layer can be designed with openings or holes, for example.

The essential property of elastomers is rubber elasticity (entropy elasticity), which is caused by extensive, irreversible crosslinking of the rubber molecules during vulcanization. Compared to semicrystalline plastics, elastomeric materials have lower modulus values in the field of application, can be deformed considerably by relatively low forces, and are able to recover their original shape to a large extent after removal of the load.

In the present invention, the core layer is required to have a sufficiently high shear modulus of more than 5MPa, in particular more than 10 MPa. Therefore, a sufficiently high crosslink density is important to obtain a sufficiently high shear modulus. The core layer may have a shear modulus of at least 5MPa, 10MPa, at least 25MPa or at least 50 MPa.

With the sandwich component of the invention, the risk of defects due to deformation of the cover layer of the sandwich component is reduced. The core layer is selected according to the invention, whereby the core layer is constructed more elastically than the first cover layer, ensuring that the elastic core layer recovers with the cover layer after an impact upon deformation, in particular upon elastic deformation of the cover layer.

Conventional sandwich components have the risk that, when the cover layer is elastically deformed, it only partially recovers after an impact, since the core layer is still plastically deformed.

The sandwich component of the invention prevents this because it ensures that the elastic deformation of the core layer is always accompanied by a deformation, in particular a recovery, of the cover layer each time the cover layer is deformed, because the elasticity of the core layer is also achieved by elasticity, as is the case with the cover layer.

According to another exemplary embodiment, the core layer is a foamed elastomer.

According to another exemplary embodiment, the core layer has a pattern of holes. In other words, the core layer is not composed of a uniform surface, but has a hole pattern to reduce weight, in which shear rigidity is maintained as much as possible. The core layer may furthermore have a plurality of corresponding grooves. With the described embodiments, material and corresponding weight of the core layer can be saved.

According to another exemplary embodiment, the core layer has a honeycomb core structure (e.g., honeycomb structure). In this way, the weight can be reduced accordingly without unduly reducing the rigidity or strength of the core layer.

According to another exemplary embodiment, the core layer is composed of at least one material component from the group consisting of natural rubber, acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), chloroprene rubber, acrylonitrile-butadiene rubber (NBR), butadiene-rubber (BR), EPDM and silicone rubber.

According to another exemplary embodiment, at least the first cover layer or the second cover layer is composed of high-strength steel. For example, the first cover layer or the second cover layer may be composed of aluminum.

According to a further exemplary embodiment, at least the first cover layer or the second cover layer consists of a fiber composite, in particular of carbon fibers and/or glass fibers (for example glass fiber-reinforced plastic or fiber-reinforced aluminum), polymer fibers (for example made of polyamide or polyaramid).

According to another exemplary embodiment, the core layer is configured to be self-adhesive for fixing on the first cover layer and/or the second cover layer.

According to another exemplary embodiment, an adhesive, in particular a hot melt adhesive or a cross-linking adhesive, is arranged between the core layer and the first cover layer or the second cover layer, for example as an adhesive film, in order to fix the core layer to the respective cover layer.

It should be noted that the embodiments described herein represent only a limited selection of possible embodiment variations of the invention. To this end, it is possible to combine features of the various embodiments with one another in a suitable manner, so that embodiment variants explicitly shown here can be regarded as obvious disclosure for a person skilled in the art. In particular, some embodiments of the invention are described by the apparatus claims and other embodiments of the invention are described by the method claims. However, it should be clear to a person skilled in the art when reading the present application that, unless explicitly stated otherwise, in addition to a combination of features of one type belonging to the subject matter of the present invention, any combination of different types or features belonging to the subject matter of the present invention is possible.

Drawings

In the following, for further explanation and better understanding of the present invention, embodiments will be described in more detail with reference to the accompanying drawings. The figure shows that:

fig. 1 shows a schematic view of a sandwich component according to an embodiment of the invention.

Fig. 2 shows a schematic view of the sandwich component of fig. 1, wherein the layers are deformed.

Figure 3 shows a schematic view of the sandwich component of figure 1 after application of an impact force.

Detailed Description

Identical or similar components in different figures are provided with the same reference numerals. The illustration in the drawings is schematically.

Fig. 1 shows a schematic view of a sandwich component 100 according to the invention. The sandwich component 100 has a first cover layer 101, a second cover layer 102 and a core layer 103. The core layer 103 is arranged between the first cover layer 101 and the second cover layer 102 such that the first cover layer 101, the core layer 103 and the second cover layer 102 form a sandwich structure. The core layer 103 has a shear stiffness of greater than 5 MPa. The core layer 103 is configured to be recoverable such that at least 95% of the original thickness of the core layer 103 is recoverable when the thickness of the core layer 103 is reduced by 20% of the original thickness d1 due to the compressive force.

For example, the core layer 103 is configured to be more elastic than at least the first cover layer 101, so that upon a punctiform elastic deformation 201 of the first cover layer 101, the core layer 103 can be elastically deformed according to the elastic deformation of the first cover layer 101.

The cover layers 101,102 are composed of a high strength material, by which the core layer is protected. The cover layer is used to absorb tensile and compressive forces. The core layer 103 is configured to be more elastic than the cover layers 101, 102. In particular, the elastic core layer 103 is used to absorb shear forces. In particular, the elastomeric core layer 103 is able to absorb higher shear forces than the cover layers 101, 102.

The first cover layer 101 or the second cover layer 102 consists of high-strength steel or a fiber composite material, in particular a fiber composite material with carbon fibers and/or glass fibers (for example glass fiber-reinforced aluminum).

A first adhesive layer 104 or a corresponding second adhesive layer 105 is arranged between the core layer 103 and the first cover layer 101 or the second cover layer 102 in order to fix the core layer 103 to the

respective cover layer

101, 102.

Fig. 2 shows the sandwich component 100 of fig. 1, wherein the layers 101 to 105 are deformed. Due to external influences or due to the sandwich element 100 falling on the floor, an impact force 200 is generated which does not act in a planar (but in a point-like) manner on the sandwich element 100. Due to the impact force 200, a first deformation 201 of the first cover layer 101 occurs, so that a second deformation 202 and a third deformation 203 of the core layer 103 and the second cover layer 102, respectively, occur.

Since the core layer 103 is constructed more elastically than the cover layers 101,102, it is ensured that the elastic core layer 103 recovers at least 95% after impact with the cover layers 101,102, in particular elastically deformed, in the case of deformation of the cover layers 101,102 in which the thickness d2 of the core layer 103 is compressed by 20% relative to the original thickness d1 of the core layer 103, since the elasticity of the core layer 103 is higher than the elasticity of the cover layers 101, 102. The sandwich component 100 according to the invention thus ensures that the core layer 103 is at least prevented from separating from the deformed cover layers 101,102 even when the sandwich component 100 is subjected to a strong impact 200.

Fig. 3 shows a schematic view of the sandwich component of fig. 1 after application of an impact force 200. The thickness d3 of the core layer after impact and after 20% compression of the core layer 103 is at least equal to 95% of the original thickness d 1. In this case, the cover layers 101,102 may be completely restored or still have dents. In both cases, the risk of separation of the core layer from the cover layers 101,102 is reduced, since there is no major deformation or reduction in thickness of the core layer 103 after impact.

Supplementary remarks it is noted that "comprising" does not exclude any other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it should also be noted that features or steps which have been described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims shall not be construed as limiting.

List of reference numerals：

100 sandwich component

101 first cover layer

102 second cover layer

103 core layer

104 first adhesive layer

105 second adhesive layer

200 impact force

201 deformation of the first cover layer

202 deformation of the second cover layer

203 deformation of the core layer

Thickness of core layer before d1 impact

Thickness of core layer during d2 impact

Thickness of core layer after d3 impact

Claims

1. A sandwich component (100) having:

a first cover layer (101) for covering the first substrate,

a second cover layer (102), and

a core layer (103) arranged between the first cover layer (101) and the second cover layer (102) such that the first cover layer (101), the core layer (103) and the second cover layer (102) form a sandwich structure, wherein the core layer (103) has a shear stiffness of more than 5MPa, wherein the core layer (103) is configured to be recoverable such that at least 95% of an original thickness of the core layer (103) is recoverable when the thickness of the core layer (103) is reduced by 20% of the original thickness due to a compressive force.

2. The sandwich component (100) according to claim 1, characterised in that the core layer (103) is configured to be elastic such that upon deformation (201) of the first cover layer (101), the core layer (103) may elastically recover according to the elastic deformation of the first cover layer (101).

3. The sandwich component (100) according to claim 1, characterised in that the core layer (103) has a material composition (100) made of a cross-linked polymer material.

4. The sandwich component (100) according to claim 1, characterised in that the core layer (103) has a material composition (100) made of a polyurethane elastomer.

5. The sandwich component (100) according to claim 1, characterised in that the core layer (103) is at least a material component selected from the group of materials consisting of natural rubber, acrylonitrile butadiene rubber (NBR), Styrene Butadiene Rubber (SBR), chloroprene rubber, acrylonitrile butadiene rubber (NBR), Butadiene Rubber (BR) and EPDM.

6. The sandwich component (100) according to claim 1, characterised in that the core layer (103) has a material composition (100) made of silicone rubber.

7. The sandwich component (100) according to claim 1, characterised in that the density of the core layer (103) is less than 800kg/m³In particular less than 500kg/m³In particular less than 250kg/m³。

8. The sandwich component (100) according to claim 1, characterised in that the core layer (103) is a foamed elastomer.

9. The sandwich component (100) according to claim 1, wherein the core layer (103) has a pattern of holes.

10. The sandwich component (100) according to claim 1, characterized in that the core layer (103) has a honeycomb core structure.

11. The sandwich component (100) according to claim 1, characterized in that at least the first cover layer (101) or the second cover layer (102) consists of high-strength steel.

12. The sandwich component (100) according to claim 1, characterised in that at least the first cover layer (101) or the second cover layer (102) consists of a fibre composite material, in particular a fibre composite material with carbon fibres and/or glass fibres, polymer fibres.

13. The sandwich component (100) according to claim 1, characterised in that the core layer (103) is of a self-adhesive construction for fixing to the first cover layer (101) and/or the second cover layer (102).

14. The sandwich component (100) according to claim 1, characterised in that an adhesive, in particular a hot melt adhesive, a cross-linked adhesive or an adhesive film, is arranged between the core layer (103) and the first cover layer (101) or the second cover layer (102) in order to fix the core layer (103) to the respective cover layer (101, 102).

15. A method for producing a sandwich component (100) according to claim 1, having

Arranging a core layer (103) between the first cover layer (101) and the second cover layer (102) such that the first cover layer (101), the core layer (103) and the second cover layer (102) form a sandwich structure, wherein the core layer (103) has a shear stiffness of more than 5MPa,

wherein the core layer (103) is configured to be recoverable such that at least 95% of an original thickness of the core layer (103) is recoverable when the thickness of the core layer (103) is reduced by 20% of the original thickness due to a compressive force.