Pourable Polyurethane Foam for Aircraft Impact Attenuation
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Solution Overview
Problem
Existing aircraft components, particularly those made of composite materials, face challenges in efficiently absorbing energy during impacts such as bird strikes, and manufacturing these components with complex contours is difficult due to the need for machining and adhesive layers, which can lead to void spaces that compromise structural integrity.
Innovation Solution
A pourable foam comprising a polymeric methylene diphenyl diisocyanate, polyol, and barium sulfate powder is used to fill void spaces in composite structures, providing energy attenuation and improved impact resistance by controlling foam cell size and homogeneity through the addition of barium sulfate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid foams are used to fill void spaces in composite structures, then structural support is provided, but machining and adhesive layers are required which increase manufacturing complexity and create additional void spaces
Solution Approach 1:
The patent changes the physical state parameter of the foam from rigid to pourable, allowing it to be injected in liquid form and then cured in place. This eliminates the need for pre-machining and adhesive layers, directly resolving the manufacturing complexity issue while maintaining structural support capability
Solution Approach 2:
The patent replaces the mechanical assembly process (machining rigid foam blocks and bonding with adhesives) with a chemical process (injecting liquid foam that cures in place). This substitution eliminates the need for mechanical fastening and reduces manufacturing steps, directly addressing the complexity problem
2Reliability
If metals are used to absorb energy through plastic deformation, then crash-worthiness is improved, but weight increases and composite material benefits are lost
Solution Approach 1:
The patent creates a composite foam material by combining polyurethane foam with barium sulfate particles. This composite structure provides both the lightweight advantage of polymers and the energy absorption characteristics needed for crash-worthiness, resolving the contradiction between weight and reliability
Solution Approach 2:
The patent modifies the foam's physical and chemical parameters by adding barium sulfate, which changes the foam's density, cell structure, and mechanical properties. These parameter changes enable the foam to absorb impact energy effectively while maintaining low weight, achieving crash-worthiness without using metals
3Productivity
If composite materials are used to reduce weight and cost, then manufacturing efficiency is improved, but energy absorption capability during impact is reduced due to lack of plasticity
Solution Approach 1:
The patent develops a composite foam system combining polyurethane with barium sulfate, creating a material that maintains the manufacturing efficiency benefits of composites while adding energy absorption capability through the composite structure itself
Solution Approach 2:
The patent applies the foam material locally within void spaces of composite structures, providing energy absorption capability exactly where needed without compromising the overall composite material benefits. The barium sulfate particles create localized energy dissipation zones within the foam matrix
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 foam enhances the crash-worthiness of composite structures by absorbing energy and maintaining structural integrity, while allowing for the creation of complex parts with reduced manufacturing complexity and improved homogeneity.
Implementation Method 1
a pourable foam comprising a first resin component comprising a polymeric methylene diphenyl diisocyanate, a second resin component comprising a polyol
Implementation Method 2
The barium sulfate component may comprise between 1% and 50% of the pourable foam... controlling foam cell size and homogeneity through the addition of barium sulfate
Implementation Method 3
providing energy attenuation and improved impact resistance by controlling foam cell size and homogeneity through the addition of barium sulfate
Data Source
AI summary
Embodiments are directed to a pourable foam comprising a first resin component comprising a polymeric methylene diphenyl diisocyanate, a second resin component comprising a polyol, and a barium sulfate powder component. The barium sulfate powder component is combined with the second resin component prior to combining the first and second resin components. The barium sulfate component may comprise between 1% and 50% of the pourable foam. The pourable foam may be used to repair or create aircraft components.