Vacuum Bagging for Aircraft Component Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for bonding aircraft components, such as co-curing with honeycomb cores, result in strength loss due to dimpling and require additional plies that add weight and cost, while conventional vacuum-bagging processes are cumbersome and often require secondary bonding steps.
Innovation Solution
A process involving the use of vacuum bagging material sealed to the lower walls and sides of preformed components, with a vent for pressure equalization, allowing for simultaneous assembly and bonding of multiple components during primary cure, eliminating the need for counterpressure devices like inflatable mandrels and enabling standardized bagging assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If co-curing methods are used to reduce steps and expense, then manufacturing efficiency is improved, but bonding strength deteriorates due to dimpling of composite plies
Solution Approach 1:
A rigid mandrel is introduced as an intermediary support structure between the composite plies during autoclave curing. The mandrel prevents dimpling by providing a solid backing surface, allowing co-curing to proceed without strength loss while maintaining manufacturing efficiency.
Solution Approach 2:
The rigid mandrel is pre-positioned within the composite layup before autoclave curing begins. This preliminary placement ensures that the mandrel is already in position to prevent dimpling during the curing process, eliminating the need for additional plies or post-curing adjustments.
2Strength
If additional plies are added to compensate for strength loss, then bonding strength is improved, but weight and cost increase
Solution Approach 1:
The problematic additional plies are removed from the design by introducing a rigid mandrel instead. The mandrel provides the necessary structural support during curing without adding permanent weight to the finished component, extracting the weight penalty while maintaining strength.
Solution Approach 2:
The rigid mandrel acts as a disposable or removable tooling element that serves its purpose during curing and then can be removed or reused. It provides temporary support during manufacturing without becoming part of the final product, avoiding permanent weight addition.
3Device complexity
If conventional vacuum-bagging processes are used, then equipment simplicity is improved, but process complexity increases due to multiple curing steps
Solution Approach 1:
The patent combines assembly and bonding operations into a single autoclave curing cycle. Components are assembled on the rigid mandrel with bonding agents applied, then the entire assembly is cured in one continuous process, merging multiple steps into one efficient operation.
Solution Approach 2:
The rigid mandrel serves multiple functions: it provides structural support during curing, maintains component positioning, enables vacuum bagging, and facilitates single-stage curing. This multi-functionality consolidates several tooling requirements into one universal fixture.
4Manufacturing precision
If inflatable mandrels are used to counterbalance autoclave pressure, then bonding uniformity is improved, but device complexity and cost increase
Solution Approach 1:
Instead of using a flexible inflatable mandrel that expands under pressure, this patent uses a rigid mandrel that maintains its shape inherently. The rigid structure provides counterbalance to autoclave pressure through its structural rigidity rather than through inflation, inverting the approach to achieve the same bonding uniformity with simpler equipment.
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
This method enhances bonding strength by ensuring even pressurization across the components and skin, reduces weight and cost by minimizing additional plies, and allows for simultaneous assembly and bonding of large structural details during the primary cure, improving efficiency and reducing the need for secondary processes.
Implementation Method 1
A vacuum is applied within the bagging material to compress the component feet with the surface to be bonded
Implementation Method 2
applying a bonding agent at intended contact points between the surface to be bonded and a plurality of preformed components
Data Source
AI summary
A process for bonding aircraft components with a surface, such as an aircraft skin, includes positioning the skin on a tool surface and placing a floorless component on the skin, with bonding agent therebetween. A vacuum bag is placed within the floorless component via a vent in the component, and sealed with opposing inner, lower walls of the component, creating a sealed surface over the skin within the component. Additional vacuum bags seal between lower, exterior legs of the floorless component and either (a) the tool surface (enclosing the skin) or (b) lower walls of adjacent aircraft components. Lower, opposing sides of the adjacent component are also bagged, and loose bag ends are sealed to the tool surface, such that the skin and all feet of the aircraft components are enclosed in vacuum bagging material. The bagged assembly is autoclave cured to bond the aircraft components with the skin.