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Incorporation of structural adhesive bonding in the preforming process of fiber composite components

Abstract

The load-bearing capacity of metal inserts in fiber composite components, which is usually insufficient, is significantly improved by applying a structural adhesive to the insert. The insert is then adhesively bonded to the fiber material during hardening, which holds the insert perfectly in place. The method allows to combine metal inserts and fibre reinforced compounds to create a load-bearing connection.

Background

The introduction of loads to fiber composite components usually is achieved through screw connections or welding with (metal) neighboring components. For this purpose, suitable screw threads, joints or inserts must be incorporated into the fiber composite components enabling the transfer of the load to the composite compound. This requires load-optimized bonding of the insert to the laminate.

Problem

The use of structural adhesives for the introduction of metal inserts subjected to high stresses into fiber composite materials is often not possible as the join partners have undercuts and are very often not geometrically joinable. Moreover, an adhesive for the local attachment of the insert can only be introduced before adding the resin and cannot be incorporated after the resin has set.

The solutions currently being used to integrate metal inserts can also lead to contact corrosion and to voltage peaks at the interface to plastic/metal upon contact to CFRP laminates. Consequently, it would be desirable to prevent weak point of the connection when joining fiber composites parts and metal inserts.

Solution

At the University of Stuttgart, a procedure has now been developed to locally attach metal components such as inserts to fiber composite compounds (preforms) by using structural adhesives before the incorporation and curing of the resin.

The adhesive is ultimately activated during the hardening of the matrix components or, optionally afterwards. This allows to connect the insert part adhesively to the fiber material. This results in an improved structural, load-transmitting connection, in particular when joining partners which differ in their material. Moreover, the insert parts need not be made of metal, but can also be made of ceramic or thermoplastics as well as duroplastic materials. The invention also enables the adhesive attachment of insert parts which have an indenting opposite the hardened fiber components. In this way, structural adhesion is possible for previously non-adhesible joint problems.

 

Composite component with integrated screw sleeve as anchorage point [image: University of Stuttgart)
Composite component with integrated screw sleeve as anchorage point [image: University of Stuttgart)

Advantages

  • Structural adhesive bonding for fiber composite components that are not geometrically joinable
  • Improved load-transmitting connection between fiber composite component and insert part
  • Improved fatigue properties of the connection of the insert on the fiber composite
  • Improved load distribution through perfectly integrated inserts
  • One-shot production of hybrid components

Fields of Application

Structural adhesive bonding for introduction of inserts into fiber composite components

 

Exposé
Contact
Dr. Dirk Windisch
TLB GmbH
Ettlinger Straße 25
76137 Karlsruhe | Germany
Phone +49 721-79004-0
windisch(at)tlb.de | www.tlb.de
Development Status
Concept/ TRL2
Patent Situation
DE 102014111176 B4 granted
Reference ID
14/014TLB
Service
Technologie-Lizenz-Büro GmbH has been entrusted with the exploitation of this technology and assists companies in obtaining licenses.