Shape Memory Structural Adhesive for Hollow Cavity Reinforcement

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Solution Overview

Problem

Hollow structural components face challenges in maintaining stability and strength while being prone to corrosion and noise transfer due to their design, and existing reinforcing elements can affect the mechanical properties of structural adhesives during the foaming process.

Innovation Solution

A composition comprising a curable structural adhesive and a thermoplastic elastomer as a penetrating polymer network, which undergoes a reversible forming method involving heating above the glass transition temperature or melting point, deformation under tension, and cooling to achieve shape memory properties without affecting the adhesive's mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If hollow structural components are used to reduce weight and material expenses, then weight and cost are reduced, but stability and strength are lost

Engineering Contradiction:

ImproveweightVSAvoidstability and strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent uses a composite material consisting of a curable structural adhesive combined with a thermoplastic elastomer forming a penetrating polymer network. This composite provides both the weight reduction benefits of hollow structures and the strength/stability of reinforcement, as the elastomer network embedded in the adhesive matrix creates a material that is both lightweight and mechanically robust.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent employs a foam structure created by the curable structural adhesive that expands to fill the hollow cavity. This porous foam material provides reinforcement while maintaining the lightweight characteristic of hollow structures, as the foam's cellular structure gives high strength-to-weight ratio.

Inventive Principle:

Principle #31Porous materials

2Loss of substance

If hollow structural components are used, then material expenses are reduced, but corrosion resistance deteriorates due to larger contact surface

Engineering Contradiction:

Improvematerial expensesVSAvoidcorrosion resistance

Core Design Contradiction:

Loss of substanceVSReliability

Solution Approach 1:

The curable structural adhesive expands to form a foam that completely fills the hollow cavity and coats the inner wall surface. This porous foam structure eliminates exposed cavity surfaces that would otherwise be susceptible to corrosion, while the adhesive material itself provides corrosion resistance protection.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent uses a cost-effective curable structural adhesive that can be applied in liquid form and then cures in place to provide permanent corrosion protection, eliminating the need for more expensive corrosion-resistant materials or additional protective coatings.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Weight of moving object

If hollow structural components are used, then weight is reduced, but noise transfer increases along the cavities

Engineering Contradiction:

ImproveweightVSAvoidnoise transfer

Core Design Contradiction:

Weight of moving objectVSObject-generated harmful factors

Solution Approach 1:

The foam structure formed by the curable structural adhesive fills the hollow cavity, creating a porous sound-absorbing material that reduces noise transfer. The cellular structure of the foam dissipates acoustic energy, preventing noise from traveling along the cavity while maintaining the lightweight design.

Inventive Principle:

Principle #31Porous materials

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 allows for efficient reinforcement of cavities in structural components by expanding in a desired direction without volume increase, effectively closing gaps and enhancing mechanical properties while maintaining noise reduction and corrosion resistance.

Implementation Method 1

heating an exemplary composition to a temperature above the glass transition temperature Tg of the curable structural adhesive

Methodology Applied

Scientific EffectGlass transition: Glassy Carbon

Implementation Method 2

heating an exemplary composition to a temperature above the glass transition temperature Tg of the curable structural adhesive, if it is an epoxy resin composition, or to a temperature above of the melting point of the curable structural adhesive, if it is a polyurethane composition

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

deforming the composition, under tension of the elastomer

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 4

a molded article formed from an exemplary composition is provided, wherein the molded article is subjected to a reversible forming method

Methodology Applied

Scientific EffectShape memory polymer effect: Shape Memory Polymer

Implementation Method 5

curing the curable structural adhesive

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 6

at least one curable structural adhesive

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS9884962B2Shape memory material based on a structural adhesive

Publication Date: 2018.02.06 SIKA TECH AG

AI summary

A composition, including at least one curable structural adhesive, and at least one thermoplastic elastomer, wherein the thermoplastic elastomer is present in the structural adhesive as penetrating polymer network. Such a composition constitutes a so-called shape memory material and is suitable for reinforcing cavities in structural components, such as, for example, in automobile bodies.