DE202018002617U1 - Connecting rod made of thermoplastic fiber composite material - Google Patents

Abstract

Connecting rod made of a fiber composite material with metallic load introduction elements (3), characterized in that the fiber composite material is made with thermoplastic matrix and the metallic load introduction elements are looped surrounded by unidirectional fiber reinforcement and this loop (1) of short fiber, long fiber or unreinforced thermoplastic (2) is surrounded.

Description

The invention relates to a connecting rod made of thermoplastic fiber composite material.

The use of high strength fiber composites, e.g. with carbon, glass, aramid, ceramic or basalt fibers, as well as a matrix, e.g. made of duromer or thermoplastic, elastomer, carbon, graphite or ceramic, requires the use of appropriate constructions for material-oriented power transmission. Appropriate for the material here means that the anisotropy of the material is exploited purposefully with regard to the different mechanical properties in the fiber direction and transversely thereto.

Connecting rods of fiber composite material for power transmission serve in particular for guidance and mechanical support, for support, for bracing or for connection. Fiber composite connecting rods have been known for many years. Such connecting rods find preferred, but not exclusive, use in aircraft or spacecraft. Connecting rods of aircraft and spacecraft, such as aircraft, rotorcraft, airships, unmanned aerial systems, rockets or satellites are mainly loaded axially by both compressive and tensile forces.

The connecting rod according to the invention is preferably but not exclusively a part of a door mechanism which is used on the aircraft. When opening and closing the door, the connecting rod in particular subject to tensile and compressive loads.

In aerospace engineering, lightweight construction is of paramount importance, as in almost no other area of engineering. Consequently, innovative lightweight construction concepts are particularly crucial for the competitiveness of many aerospace components.

Connecting rods in the door mechanism are so far mainly made of aluminum materials. The use of fiber composites, in particular of carbon fiber reinforced plastics can be achieved in such connecting rods significant weight savings. The use of, for example, glass fiber reinforced plastics can also serve to save costs.

To initiate high tensile forces in fiber composite components, the loop-shaped arrangement of the fiber reinforcement is suitable with fiber orientation running tangentially to the load introduction elements.

Fiber composite struts are already known from the prior art, which use loops for load introduction.

DE 10 2005 027 173 A1 describes a train strut, wherein a pull loop the tensile load and a pressure loop transmits the compressive load and these two loops are connected to a force introduction element such that the pull loop and the pressure loop is loaded via the support surface on the outer diameter of the pressure loop.

DE 10 2006 047 412 B4 describes a rod-shaped fiber composite structure with metallic load introduction elements, consisting of a rod-shaped fiber composite part and at the ends of the rod-shaped fiber composite part positively held metallic load introduction elements, the rod-shaped fiber composite part of shell-shaped base components consists mainly with axial fiber reinforcement, the base components each formed at their ends for positive reception of a load introduction element and the shell-shaped base components are interconnected, and the base components are surrounded by a banding with circumferential fiber reinforcement.

DE 10 2014 226 408 A1 discloses a plastic composite member having an endless fiber-wound core structure, the continuous fibers being embedded in a matrix mass and thus forming a fiber-plastic composite structure at least partially surrounding the core structure. Preferably, the plastic mass of the core structure and the plastic mass of the surrounding fiber-plastic composite structure are different (eg. Thermoplastic plastic material for the core structure and thermoset plastic material for the fiber-plastic composite structure).

In DE 33 17 046 A1 is described a connecting rod with circumferential, outer belt and a core of fiber reinforced resin, core and belt are one-piece and the core consists of a glass or carbon fiber laminate based on a heat-resistant resin.

In the known types of fiber composite material, the use of core structures for the production of the component is partly required, which increases the production cost, or the loop is not embedded by additional matrix mass, or there are thermoset materials used which lead to high manufacturing costs.

The invention is based on the problem to develop a connecting rod made of fiber composite, which with low complexity of Component and a low production cost can absorb high forces.

In addition, any impact damage to the connecting rod should be detected as early as possible. When using fiber composite components, for example in the field of aviation, there is the problem that impact-induced damage in the fiber composite can not be detected by visual methods since impact-induced damage to fiber composite materials on the material surface becomes visually visible only from very high impact energies.

Among other things, the Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA) prepared a damage classification for the early detection of a so-called "barely visible impact damage" English Barely Visible Impact Damage (BVID). The so-called "barely visible impact damage" is also abbreviated below as "BVID". Despite pre-damage, components must be able to withstand their design loads, with the extent of the pre-damage being not the impact energy but the visual visibility of the impact damage.

A component design that improves the visual visibility of any impact load that has occurred makes it possible to produce lighter components because less additional material is needed to compensate for the damage up to the BVID.

The aim of the invention is therefore to obtain a connecting rod made of fiber composite material by means of a loop connection, which can transmit the highest possible tensile and compressive loads in tight space. The connecting rod should be kept as slim as possible, light and inexpensive.

In addition, the early display of BVID is to be improved on the surface of the connecting rod, so that a distinction can be made visually between a damaged and an undamaged fiber composite material.

The object is achieved in that the tensile force is introduced via two metallic load introduction elements in a loop-shaped unidirectional fiber reinforcement and the loop, and the metallic load introduction elements are surrounded by kurzfaser-, langfaser- or unreinforced thermoplastic.

In case of limited installation space, the loop between the load introduction elements can be made asymmetrical. In this way, space can be saved on one side of the connecting rod.

Another configuration which has a positive effect on the compressive strength of the connecting rod provides that the unidirectional fiber reinforcement of the loop additionally encloses in each case several times in each case the metallic load introduction elements.

Furthermore, here additionally favoring unidirectionally reinforced elements made of fiber composite material with a thermoplastic matrix in the connecting rod can be provided, which increase the buckling strength of the connecting rod.

The task of early indication of BVID is solved by the structure of the connecting rod made of short-fiber, long-fiber or unreinforced thermoplastic. The structuring can for example consist of homogeneously distributed elevations. In the case of an impact load, the elevations in the area of the impact-stressed area of the structured surface deform even at low impact energies, resulting in visually good detectable BVID. The absence of an additional surface coating for the early detection of BVID thus reduces the costs and the weight of the connecting rod.

For fine adjustment of the visual display of BVID the structuring of the surface can be adjusted. To indicate lower or higher impact energies, the elevations in the surface may be made higher or less high, narrower or wider, so that plastic deformation occurs in the material in the elevations correspondingly at lower or higher energies.

Also by selecting the thermoplastic present on the surface of the connecting rod as well as its share of reinforcing fibers and possible additional fillers, the fine adjustment of the visual indication of BVID is used.

• 1 zwei schematische Schnittansichten der erfindungsgemäßen Verbindungsstange mit metallischen Lasteinleitungselementen (3), Schlaufe (1), kurzfaser-, langfaser- oder unverstärktem Thermoplast (2) und einem zusätzlichen unidirektional verstärkten Element aus Faserverbundwerkstoff mit thermoplastischer Matrix (4).
• 2 eine schematische Ansicht mit Schnitt der erfindungsgemäßen Verbindungsstange mit metallischen Lasteinleitungselementen (3), Schlaufe (1), kurzfaser-, langfaser- oder unverstärktem Thermoplast (2) und drei zusätzlichen unidirektional verstärkten Elementen aus Faserverbundwerkstoff mit thermoplastischer Matrix (4).
• 3 eine schematische Ansicht mit Schnitt der erfindungsgemäßen Verbindungsstange mit Schlaufe (1), kurzfaser-, langfaser- oder unverstärktem Thermoplast (2), einem zusätzlichen unidirektional verstärkten Element aus Faserverbundwerkstoff mit thermoplastischer Matrix (4) und mehrfach vollständig von unidirektionaler Faserverstärkung umgebenen metallischen Lasteinleitungselementen (3).

Show it:

• 1 two schematic sectional views of the connecting rod according to the invention with metallic load introduction elements (3), loop (1), short fiber, long fiber or unreinforced thermoplastic (2) and an additional unidirectionally reinforced fiber composite element with thermoplastic matrix (4).
• 2 a schematic view with section of the connecting rod according to the invention with metallic load introduction elements (3), loop (1), short fiber, long fiber or unreinforced thermoplastic (2) and three additional unidirectionally reinforced fiber composite elements with thermoplastic matrix (4).
• 3 a schematic view with section of the connecting rod according to the invention with loop (1), short fiber, long fiber or unreinforced thermoplastic (2), an additional unidirectionally reinforced fiber composite element with thermoplastic matrix (4) and several times completely surrounded by unidirectional fiber reinforcement metallic load introduction elements (3 ).

LIST OF REFERENCE NUMBERS

(1)

loop

(2)

short fiber, long fiber or unreinforced thermoplastic

(3)

metallic load introduction element

(4)

unidirectionally reinforced fiber composite element with thermoplastic matrix

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005027173 A1 [0009]
• DE 102006047412 B4 [0010]
• DE 102014226408 A1 [0011]
• DE 3317046 A1 [0012]

Claims (7)

Connecting rod made of a fiber composite material with metallic load introduction elements (3), characterized in that the fiber composite material is made with thermoplastic matrix and the metallic load introduction elements are looped surrounded by unidirectional fiber reinforcement and this loop (1) of short fiber, long fiber or unreinforced thermoplastic (2) is surrounded. Connecting rod made of a fiber composite material with metallic load introduction elements (3) according to Claim 1 , characterized in that the metallic load introduction elements are multi-layer loop-shaped surrounded by unidirectional fiber reinforcement. Connecting rod made of a fiber composite material with metallic load introduction elements (3) according to Claim 1 , characterized in that the loop is asymmetric between the load introduction elements. Connecting rod made of a fiber composite material with metallic load introduction elements (3) according to Claim 1 , characterized in that in the connecting rod one or more additional unidirectionally reinforced elements of fiber composite material with thermoplastic matrix (4) are located. Connecting rod made of a fiber composite material with metallic load introduction elements (3) according to Claim 1 , characterized in that the surface of the connecting rod is designed structured for the detection of impact damage. Connecting rod made of a fiber composite material with metallic load introduction elements (3) according to Claim 1 , characterized in that the metallic load introduction elements (3) are repeatedly completely surrounded by unidirectional fiber reinforcement. Connecting rod made of a fiber composite material with metallic load introduction elements (3) according to Claim 1 to 6 , characterized in that the connecting rod is used as part of a door mechanism on the aircraft.

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