L-Shaped Panel Bonding with Dual-Modulus Adhesives

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Solution Overview

Problem

Existing methods for assembling vehicle body panels using high stiffness adhesives often result in joint failures due to forces applied during driving, leading to panel disengagement.

Innovation Solution

The use of a combination of two adhesives with different elastic moduli, where a first adhesive with a higher elastic modulus provides shear stiffness and a second adhesive with a lower elastic modulus acts as a peel-resistant adhesive, bonded in specific regions to form an L- or T-shaped assembly, with the second adhesive sealing the first adhesive and enhancing flexibility and peel resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high stiffness adhesives are used to bond panels, then shear stiffness is improved, but peel resistance deteriorates leading to joint failure

Engineering Contradiction:
Improveshear stiffnessVSAvoidjoint failure resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The bonding system is segmented into two distinct adhesive layers: a first adhesive layer providing shear stiffness and a second adhesive layer providing peel resistance. This segmentation allows each layer to specialize in one function, resolving the contradiction between shear stiffness and peel resistance that plagues single-adhesive systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses a composite adhesive system combining two adhesives with different mechanical properties. The first adhesive (higher elastic modulus) and second adhesive (lower elastic modulus) work together in a composite configuration, where the first layer provides structural rigidity and the second layer provides flexibility and peel resistance, thereby achieving both shear stiffness and joint reliability.

Inventive Principle:
Principle #40Composite materials

2Strength

If panels are assembled using separate coupling means such as bolts and nuts, then structural joining is achieved, but device complexity increases

Engineering Contradiction:
Improvestructural joiningVSAvoidassembly complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The invention replaces mechanical fastening systems (bolts, nuts, and other coupling means) with a chemically-bonded adhesive system. This substitution eliminates the complexity of mechanical assembly while providing equivalent or superior structural joining, as the adhesive layers create continuous bonds without the discrete fasteners required by mechanical systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If a single adhesive layer is used to bond panels, then manufacturing process is simplified, but reliability under driving forces deteriorates

Engineering Contradiction:
Improvebonding process simplicityVSAvoidpanel disengagement resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The bonding system is segmented into two distinct adhesive layers: a first adhesive layer providing shear stiffness and a second adhesive layer providing peel resistance. This segmentation allows each layer to specialize in one function, resolving the contradiction between shear stiffness and peel resistance that plagues single-adhesive systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the parameter of adhesive elastic modulus by using two different adhesives with different moduli. The first adhesive has a higher elastic modulus for shear stiffness, while the second adhesive has a lower elastic modulus for peel resistance and flexibility. This parameter differentiation enables the system to withstand both shear and peel forces effectively.

Inventive Principle:
Principle #35Parameter changes

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

This approach minimizes the risk of panel disengagement by distributing forces effectively, enhancing the bond's rotational and transverse strength while preventing cleavage and peel failure, thus improving the structural integrity of the vehicle body.

Implementation Method 1

The panels are bonded by using at least a first adhesive (4) having a first elastic modulus and a second adhesive (5) having a second elastic modulus that is lower than the first elastic modulus. The first adhesive bonds the panels in a first region

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

the second adhesive bonds the panels in a second region, the second region being arranged next to the first region, when seen in the cross sectional view. the second adhesive avoids cleavage of the first adhesive and is acting as the peel resistant adhesive

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3699441B1Assembly of a first and second panel
Publication Date: 2024.05.01 EBUSCO BV
  • EP3699441B1 patent drawingFigure 1
  • EP3699441B1 patent drawingFigure 2~3
  • EP3699441B1 patent drawingFigure 4

AI summary

There is provided an assembly of a first panel (1) and a second panel (2), wherein a head end surface (12) of the first panel is connected to a side surface (22) of the second panel, the assembly having an L-shape or T-shape when seen in a cross sectional view. The panels are bonded using at least a first adhesive (4) having a first elastic modulus (λ1) and a second adhesive (5) having a second elastic modulus (λ2) that is lower than the first elastic modulus (λ1). The first adhesive bonds the panels in a first region, and the second adhesive bonds the panels in a second region, wherein the second region is arranged next to the first region, when seen in the cross sectional view.