Foam-Reinforced Joint Assembly With Cavity-Based Adhesion

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Solution Overview

Problem

Joint assemblies made from non-traditional materials like plastic in furniture often fail due to lack of adhesion between polyurethane foam and reinforcing members, leading to stress concentrations and structural weaknesses under normal or significant forces.

Innovation Solution

Creating cavities on the surfaces of joint members and reinforcing members to increase the contact area, and using methods such as acid etching, electric current treatment, or solvent application to lower the dielectric value and enhance adhesion between polyurethane foam and the components, thereby improving the bonding between foam and joint members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polyurethane foam is introduced into hollow joint members to strengthen the assembly, then the structural strength is improved, but the foam separates from the inner surfaces and reinforcing member due to lack of adhesion

Engineering Contradiction:

Improvejoint assembly strengthVSAvoidfoam adhesion

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The inner surfaces of the joint members and the surface of the reinforcing member are made porous through cavity formation. This porosity increases the surface area and allows the polyurethane foam to mechanically interlock with the surfaces, preventing separation and improving adhesion reliability while maintaining the strengthening function.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The dielectric value of the surfaces is modified through treatments such as acid etching, solvent application, or electric current treatment. This parameter change enhances the chemical and physical bonding properties of the surfaces, improving foam adhesion and preventing separation under stress.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If the inner surfaces of joint members are made smooth as in conventional tubing, then manufacturing is easier, but adhesion between foam and surfaces is insufficient

Engineering Contradiction:

Improvejoint member manufacturingVSAvoidfoam-to-surface bonding

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

Instead of maintaining smooth surfaces, the invention introduces cavities and porosity into the inner surfaces of joint members. This increases the surface area for foam contact and provides mechanical interlocking, significantly improving bonding strength while the cavity formation processes remain compatible with manufacturing workflows.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

Surface treatments such as acid etching, solvent application, or electric current treatment are applied to modify the dielectric value and surface properties. These treatments enhance adhesion without requiring complete redesign of the manufacturing process, balancing ease of manufacture with improved bonding.

Inventive Principle:

Principle #35Parameter changes

3Strength

If reinforcing members are placed inside joint members to prevent damage, then structural integrity is improved, but the foam separates from the reinforcing member under stress

Engineering Contradiction:

Improvejoint assembly integrityVSAvoidfoam-to-reinforcing member adhesion

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The surface of the reinforcing member is made porous with cavities that allow the polyurethane foam to mechanically interlock. This prevents separation between the foam and reinforcing member under stress, ensuring that the reinforcing member continues to provide structural integrity throughout the joint assembly's service life.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The dielectric value of the reinforcing member surface is modified through treatments such as acid etching, solvent application, or electric current treatment. This parameter modification enhances the bonding between the foam and reinforcing member, preventing separation and maintaining structural integrity under various loading conditions.

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

The enhanced adhesion results in a joint assembly that is less susceptible to failure, demonstrating a 34% increase in strength during stress testing cycles by maintaining the laminate effect and distributing forces effectively.

Implementation Method 1

lowering the dielectric value of the reinforcing member to promote wetting of the foam

Methodology Applied

Scientific EffectDielectric: Dielectric

Implementation Method 2

The liquid polyurethane foam expands and hardens into a rigid structure when set

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 3

increased adhesion is realized between the foam and the joint members and/or reinforcing members

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS8870488B2Joint assembly with reinforcing member and foam

Publication Date: 2014.10.28 DURACASE

AI summary

First and second joint members are connected to one another. A reinforcing member that has an outer surface that defines a plurality of cavities is located in at least one of the joint members. Foam is located in the joint members and engages the reinforcing member and is located in the cavities of the reinforcing member.