Curved Adhesive Bead for Tailgate Reinforcement Bonding

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Solution Overview

Problem

The existing subassemblies of vehicle tailgates with reinforcing elements secured by glue beads suffer from cracking and peeling due to stress concentration at the ends, leading to operational difficulties in closing or opening the tailgate, as the adhesive degradation affects the correct positioning of lock components.

Innovation Solution

A subassembly design featuring a semi-circular adhesive bead with a diameter of at least 5 mm, positioned close to the free end of an elongated fixing surface with a lateral protuberance to distribute stress evenly, preventing detachment or cracking without additional fixing means or modifying the glue type.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a bead of adhesive is used to secure the reinforcing element to the covering element, then the reinforcing element is rigidly fixed to the covering element, but the ends of the adhesive bead crack and/or peel off over time due to stress concentration

Engineering Contradiction:

Improvebond strengthVSAvoidadhesive bead durability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The end of the adhesive bead is formed with a curved profile having a radius of curvature of at least 0.5 mm, replacing the conventional sharp or flat end. This curvature distributes the stress applied during tailgate opening/closing operations across a broader area of the adhesive bead, preventing stress concentration at the endpoint that causes cracking and peeling, while maintaining the rigid bonding function between the reinforcing element and covering element

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of manufacture

If the adhesive bead endpoint is sharp or flat, then the assembly process is simple, but stress concentration occurs at the ends during tailgate operation

Engineering Contradiction:

Improveassembly simplicityVSAvoidstress concentration

Core Design Contradiction:

Ease of manufactureVSStress or pressure

Solution Approach 1:

The adhesive bead is formed with a curved endpoint profile (radius ≥ 0.5 mm) during the dispensing or curing process. This curvature can be achieved through controlled adhesive application methods or post-forming techniques that are integrated into existing manufacturing processes, thereby distributing operational stresses while maintaining manufacturing feasibility without requiring complex additional steps

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If additional fixing means are added to prevent adhesive degradation, then the positioning reliability improves, but the production cost increases

Engineering Contradiction:

Improvelock positioning accuracyVSAvoidfixing means complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The solution modifies the geometric parameter of the adhesive bead (endpoint curvature radius ≥ 0.5 mm) rather than adding additional fixing components. This parameter change optimizes the stress distribution characteristics of the existing adhesive bond, maintaining reliable positioning of lock components without introducing additional parts, assembly steps, or cost increases

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3254875B1Subassembly comprising two parts assembled together by a bead of adhesive and vehicle including such a subassembly

Publication Date: 2019.01.02 PSA AUTOMOBILES SA

Figure 1~2

AI summary

The invention relates to a subassembly comprising a trim element (1) and a reinforcement element (3), the reinforcement element (3) being rigidly bonded to the trim element (1) by a bead of adhesive (4), characterized in that at least one end of the adhesive bead (4) forms a loop (41). The invention also relates to a vehicle comprising such a subassembly.