Vacuum Barrier System for Hollow Composite Structures
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Solution Overview
Problem
Conventional methods for forming hollow composite structures are time-consuming, labor-intensive, and require mechanical fasteners, which increase weight and disrupt aerodynamics, while inflatable mandrels struggle with accuracy and high-temperature materials.
Innovation Solution
A vacuum barrier system comprising a bag carrier with an over-molded bladder, where the bag carrier is configured complementary to the composite part, and a method involving a soluble forming mandrel, composite material layup, and curing with a forming mandrel vacuum bag, followed by de-bagging, trimming, and washing out the mandrel to create a durable, reusable tooling system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical fasteners are used to assemble composite components, then the composite structure can be assembled, but the overall weight increases and aerodynamics are disrupted
Solution Approach 1:
The patent merges multiple composite components into a single integrated component formed in one curing cycle, eliminating the need for mechanical fasteners to assemble separate parts. The bag carrier with integrated ribs, spars, and skin members creates a monolithic structure that maintains strength while reducing weight and improving aerodynamics.
Solution Approach 2:
The invention segments the manufacturing process into a single forming operation that produces all structural elements (skin members, ribs, spars) as one integrated component, rather than assembling segmented parts with fasteners. This segmentation at the design level eliminates the need for mechanical connections.
2Strength
If mechanical fasteners are used to assemble composite components, then the composite structure can be assembled, but the assembly process becomes time-consuming and labor-intensive
Solution Approach 1:
The patent combines multiple assembly operations into a single forming operation. All components (skin members, ribs, spars) are formed and integrated in one curing cycle, eliminating time-consuming assembly steps and labor-intensive fastener installation while maintaining structural strength.
Solution Approach 2:
The invention performs preliminary action by pre-forming all structural elements with their final geometries and integrating them during the initial curing process. The bag carrier is designed with pre-formed ribs, spars, and skin members that are consolidated in one operation, eliminating subsequent assembly steps.
3Stress or pressure
If an inflatable mandrel is used to form hollow composite structures, then internal compaction pressure can be applied, but the ability to form part surface geometry to high accuracy is limited
Solution Approach 1:
The patent uses a flexible bag carrier made of composite material that can be molded to precise geometries. This flexible shell provides both the internal compaction pressure capability and the high surface geometry accuracy, as the bag carrier itself becomes part of the final structure with dimensionally accurate surfaces.
Solution Approach 2:
The invention replaces the traditional inflatable mandrel system with a bag carrier that integrates the vacuum barrier function and the forming surface function. The bag carrier's pre-formed geometry directly defines the part surface accuracy, eliminating the need for a separate inflatable mandrel that limits precision.
4Stress or pressure
If an inflatable mandrel is used to form hollow composite structures, then internal compaction pressure can be applied, but use with composite materials having high processing temperatures is limited
Solution Approach 1:
The patent uses a bag carrier made of high-temperature resistant composite materials that can withstand the processing temperatures required for curing various composite materials. This composite bag carrier maintains its structural integrity and vacuum barrier function at elevated temperatures, unlike traditional inflatable mandrels.
Solution Approach 2:
The invention replaces the inflatable mandrel system with a composite bag carrier that is inherently stable at high temperatures. The composite material construction allows the vacuum barrier to function reliably during high-temperature curing processes without degradation.
5Ease of manufacture
If conventional forming methods are used for hollow composite structures, then the process is relatively simple, but reusable tooling durability and useful life are reduced
Solution Approach 1:
The patent uses a flexible bag carrier that can be removed and reused multiple times. The bag carrier's flexible composite construction allows it to withstand repeated curing cycles while maintaining its vacuum barrier integrity and geometric accuracy, extending tooling useful life while keeping the process simple.
Solution Approach 2:
The invention implements a recoverable tooling system where the bag carrier is discarded after each use in favor of a reusable carrier. This approach maintains process simplicity while significantly extending the useful life of the core tooling components, as the permanent mold and bag carrier can be reused many times.
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
Enables the formation of hollow, non-draftable composite structures with high accuracy and reduced weight, eliminating the need for mechanical fasteners and improving aerodynamics, while providing a simple, cost-effective, and long-lasting composite forming system.
Implementation Method 1
washing out the soluble forming mandrel
Implementation Method 2
drawing a vacuum on a tool interior, and applying an internal compaction pressure on the composite part against the OML tool surface
Data Source
AI summary
A method of fabricating a vacuum barrier system includes fabricating a soluble forming mandrel, laying up composite material over the soluble forming mandrel, and applying a forming mandrel vacuum bag over the composite material and curing the composite tooling material to form a cured composite bag carrier. The method also includes de-bagging and trimming the cured composite bag carrier.