Curable Epoxy Adhesives for Irregular Aerospace Gaps
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Solution Overview
Problem
In aerospace assembly operations, there is a need for effective materials to fill residual gaps between assembled parts with tight tolerance requirements, as traditional shims may not adequately address irregular or tapered interfaces.
Innovation Solution
A curable epoxy composition comprising a combination of epoxy resin and epoxy curative, where the curative includes a cyclic amine and a polyether polyamine with a specific terminal aminoalkyl residue, is used to fill gaps between assembled parts, allowing for curing and optional sanding or coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional solid shims are used, then the assembly process is simple, but they cannot adequately fill irregular or tapered interfaces
Solution Approach 1:
The patent transforms the shim material from a solid rigid state to a curable liquid state, allowing it to flow and adapt to irregular interfaces. The composition changes from liquid to solid through curing, enabling it to fill complex geometries while maintaining structural integrity.
Solution Approach 2:
The patent uses a composite epoxy system combining multiple epoxy resins with specific curatives to achieve both flowability for filling irregular gaps and high strength for structural support. The composite formulation balances adaptability and mechanical properties.
2Adaptability or versatility
If curable shim materials are used to fill irregular interfaces, then the adaptability improves, but the curing process and composition complexity increase
Solution Approach 1:
The patent pre-formulates the epoxy composition with specific ratios of resins and curatives before application. The composition is prepared in advance with all necessary components mixed in correct proportions, simplifying the application process while ensuring optimal curing and performance.
3Strength
If high modulus epoxy adhesives are used, then the compressive strength increases, but the formulation complexity increases
Solution Approach 1:
The patent employs a composite epoxy system combining multiple resin types (aromatic and aliphatic) with specific curatives to achieve high compressive strength. The synergistic interaction between components produces superior mechanical properties while maintaining manageable formulation complexity through systematic composition design.
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 curable epoxy composition provides strong mechanical properties, including high compressive strength at room and elevated temperatures, enabling effective shimming of larger gaps and maintaining stability in aircraft components.
Implementation Method 1
a curable composition comprising at least one epoxy resin and at least one epoxy curative composition as a curable shim for filling gaps between two assembled parts of an assembly
Data Source
AI summary
Use of a curable composition comprising at least one epoxy resin and at least one epoxy curative composition as a curable shim for filling gaps between two assembled parts of an assembly, wherein the epoxy curative composition comprises at least a first and a second curative wherein the first curative is selected from a cyclic amine having at least one primary amino (—NH2) group and a second curative selected from at least one polyether polyamine comprising at least one polyether unit and separated therefrom by a linking group at least one polyamine unit and further comprising at least one terminal aminoalkyl residue that is branched and comprises a primary amino group (—NH2) and an alkyl branch in an α-, β- or γ-position to the primary amino group wherein the alkyl branch contains from 1 to 6 carbon atoms.