Mixed-Material Component Assembly With Differential Thermal Expansion Compensation

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Solution Overview

Problem

The connection of components with different coefficients of thermal expansion in mixed-material constructions, such as in vehicle manufacturing, often leads to high local stresses during heating/drying processes, causing damage to the joining elements and adhesive layers, which can result in component failure.

Innovation Solution

The use of a combination of fixed and floating bearings, along with a non-uniform adhesive gap design, such as a V-adhesive gap, allows for differential thermal expansion while minimizing stresses, using components like rivets, threaded bolts, or plastic clips to secure the assembly, ensuring the adhesive gap thickness adjusts with distance from the fixed bearing, thus maintaining structural integrity and reducing adhesive usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If components with different coefficients of thermal expansion are firmly connected using rigid fixation, then structural stability is improved, but high local stresses occur during thermal processes causing damage to joining elements and adhesive layers

Engineering Contradiction:
Improvestructural stabilityVSAvoiddamage-free bonding
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The fixation system is segmented into multiple bearing points (first bearing point and second bearing point) along the longitudinal direction. This segmentation allows different portions of the composite component to have different degrees of freedom, with some areas providing stable fixation and others allowing thermal expansion compensation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic adaptability into the fixation system by allowing certain bearing points to accommodate thermal expansion movements. The bearing points are positioned and designed to enable the structure to dynamically adjust to thermal stresses without compromising overall stability.

Inventive Principle:
Principle #15Dynamics

2Ease of manufacture

If the adhesive gap has uniform thickness, then manufacturing simplicity is improved, but the adhesive layer cannot accommodate differential thermal expansion causing stress concentration

Engineering Contradiction:
Improveadhesive gap uniformityVSAvoidstress distribution
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The adhesive gap thickness is varied locally along the longitudinal direction of the composite component. The gap is thicker in regions where thermal expansion differences are expected to be greater, allowing the adhesive layer to accommodate differential expansion without stress concentration, while maintaining thinner gaps in regions requiring stronger bonding.

Inventive Principle:
Principle #3Local quality

3Reliability

If more adhesive is used to ensure complete coverage, then bonding reliability is improved, but weight and material cost increase

Engineering Contradiction:
Improvebonding completenessVSAvoidcomponent weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The adhesive is applied in a strategically varied pattern rather than uniform coverage. Higher adhesive concentration is applied in regions requiring stronger bonding, while thinner or reduced adhesive application is used in regions where the structural design already provides adequate connection, thereby reducing overall adhesive usage while maintaining bonding reliability.

Inventive Principle:
Principle #3Local quality

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 prevents damage to the joining elements and materials, ensures reliable bonding, and minimizes adhesive usage while maintaining process efficiency and lightweight construction, ensuring the composite component's properties are preserved and its rigidity is maintained.

Implementation Method 1

components with different coefficients of thermal expansion... high local stresses can occur on the individual components or the so-called joining partners, the joining elements and the adhesive layer

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The connection properties are guaranteed by the bonding. In other words, the necessary different length displacement between the components is realized by suitable technical measures, namely so-called floating fixation... until the adhesive is crosslinked or hardened

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Data Source

PatentEP2546124B1Sub-assembly and method for connecting components with different thermal expansion coefficients
Publication Date: 2018.08.22 BAYERISCHE MOTOREN WERKE AG
  • EP2546124B1 patent drawingFigure 1~5

AI summary

The component assembly (10) has two components (11,12) which are formed of different materials and different coefficient of thermal expansion. The components are communicated with each other via an adhesive material (13). The components are interconnected by a fixed bearing (14) and a movable bearing (15). An independent claim is included for method for connecting two components with different coefficient of thermal expansion.