Fiber-Reinforced Strut Connection Shoe for Corrosion-Free Rigidity
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Solution Overview
Problem
Existing fiber-reinforced stiffening struts for motor vehicles face issues with reduced rigidity due to adhesive connections, susceptibility to corrosion, and the need for regular retightening of screw connections, which compromises their effectiveness in enhancing body rigidity and crash safety.
Innovation Solution
A fiber-reinforced stiffening strut design featuring a connection shoe with a through-opening that allows force introduction in a form-fitting manner, using a metallic connection shoe and a collar sleeve to divert clamping forces, preventing direct contact with the FRP material and reducing the risk of corrosion, while maintaining high rigidity and allowing for a maintenance-free connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive connection is used to connect the strut to the body, then the connection is simple to manufacture, but the rigidity of the connection is low and deformations occur at the connection point
Solution Approach 1:
The connection system is segmented into multiple components: the strut body, connection elements at the strut ends, and separate adhesive application points. This segmentation allows the rigid connection elements to handle mechanical loads while adhesive provides sealing and secondary bonding, resolving the contradiction between ease of manufacture and connection rigidity.
Solution Approach 2:
The connection system uses a composite approach combining rigid connection elements (made of metal or rigid plastic) with adhesive material. This composite structure leverages the high rigidity of the connection elements while maintaining the manufacturing simplicity of adhesive application, effectively resolving the contradiction between ease of manufacture and connection strength.
2Strength
If screw connection is used directly to the FRP strut, then the connection is strong, but the screw connection sets due to creep and requires regular retightening
Solution Approach 1:
Connection elements are introduced as intermediary components between the screw connection and the FRP strut body. These intermediaries distribute the clamping forces over a larger area and prevent direct concentration of forces on the FRP material, eliminating creep-induced loosening while maintaining strong connections.
Solution Approach 2:
The connection elements are pre-installed on the FRP strut during manufacturing, creating a stable interface before the screw connection is applied. This preliminary action ensures that the screw connection acts on a rigid, pre-positioned element rather than directly on the FRP material, preventing future settling and eliminating the need for retightening.
3Device complexity
If screw connection is used directly to the FRP strut, then the connection is simple, but corrosion can occur due to conductivity of reinforcing fibers and penetrating moisture
Solution Approach 1:
Connection elements serve as intermediary components that electrically isolate the metal screw connection from the conductive FRP material. By positioning these intermediaries between the screw and the FRP strut, the design blocks the corrosion pathway created by moisture penetration and fiber conductivity, effectively preventing galvanic corrosion while adding minimal complexity.
4Object-affected harmful factors
If the passage opening diameter is larger than the screw diameter, then the screw force does not contact the FRP material, but the connection requires additional precision in alignment
Solution Approach 1:
The connection elements are designed to self-align during assembly, with features such as tapered sections, locating pins, or snap-fit mechanisms that automatically position the connection element correctly on the FRP strut. This self-alignment capability compensates for the larger passage opening diameter, maintaining corrosion protection without requiring excessive manufacturing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides enhanced overall rigidity, improved crash safety, and corrosion resistance, eliminating the need for regular retightening of screw connections, thus ensuring a more stable and durable motor vehicle body structure.
Implementation Method 1
The passage opening is particularly preferably designed in such a way that the screw does not lie against the FRP material of the strut at the side... The connection shoe rests on the other side (on the body side) on the body part to be connected, so that the force is also introduced into the FRP strut via the connection shoe on this side.
Implementation Method 2
The generic DE 10 2010 053 850 A1 relates to a motor vehicle body with fiber-reinforced stiffening struts. The stiffening struts there have a connecting section at both ends, with which they are connected to the body. The connection sections can be glued ring lugs that resemble a ring cable lug.
Data Source
Figure 1
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Figure 4
AI summary
The invention relates to a fiber-reinforced reinforcement strut (1) which has an elongated profiled strut section (11) made of a fiber-reinforced material and which has at least one end-face attachment portion. At least one passage opening (11') is provided in the end-face attachment portion perpendicularly to the longitudinal axis of the profiled strut section (11). The at least one attachment portion has an attachment shoe (12) with a closed cross-section, said shoe being pressed over the profiled strut section (11). The inner cross-section of the attachment shoe (12) corresponds to the outer cross-section of the profiled strut section (11), and the attachment shoe (12) has a passage opening (12') which lies at least partly over the passage opening (11') of the profiled strut section (11). The invention further relates to a method for producing a reinforcement strut (1) according to the invention and to a motor vehicle body with at least one reinforcement strut according to the invention.