Mandrel Pressure Forming of Honeycomb Panels Without Core Crush
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Solution Overview
Problem
Existing processes for manufacturing structural panels, such as those for aircraft propulsion systems, often deform the honeycomb core during shaping due to significant pressure requirements, especially when forming complex geometries, leading to potential damage and defects.
Innovation Solution
A manufacturing process involving a tubular body with a mandrel, where a porous first skin, a solid second skin, and a cellular core are arranged to form a pressure vessel, with pressurized fluid used to shape the heated panel to conform to the mandrel's outer surface, avoiding direct pressure on the honeycomb core and thus minimizing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If significant pressure is applied to shape the panel to complex geometries, then the panel can be formed to the desired shape, but the honeycomb core is crushed or deformed
Solution Approach 1:
The pressure application is segmented into two distinct zones: an outer pressure vessel that applies pressure to the panel skins, and an inner cavity that remains at atmospheric pressure to support the honeycomb core. This segmentation allows independent pressure control for shaping versus core protection.
Solution Approach 2:
A support structure (mandrel or internal support members) is introduced as an intermediary between the honeycomb core and the pressure loading path. This intermediary directly supports the core cells during forming, preventing them from collapsing under the applied pressure.
2Shape
If the panel is pressed against a die with an inflatable pressure vessel, then the panel can assume the desired shape, but the honeycomb core portion is crushed or deformed
Solution Approach 1:
The pressure vessel is segmented into an outer wall that contacts the panel for shaping and an inner cavity that excludes pressure from the core region. This allows the panel to be formed while the core remains in a protected, lower-pressure environment.
Solution Approach 2:
A support mandrel or internal support structure acts as an intermediary that directly bears against the honeycomb core, preventing pressure transmission to the core cells while allowing the outer panel to be formed to the desired geometry.
3Manufacturing precision
If pressure is applied to form complex curved geometries, then the panel can be shaped accurately, but the cellular core is deformed
Solution Approach 1:
The forming process segments pressure application to affect only the panel skins through the outer pressure vessel, while the inner cavity maintains atmospheric pressure to preserve core cell geometry. This enables independent control of skin forming and core integrity.
Solution Approach 2:
A support structure positioned within the panel acts as an intermediary that mechanically supports the honeycomb core during forming, preventing deformation while allowing the outer surfaces to be formed to complex geometries with high precision.
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 process allows for the formation of structural panels with complex geometries without deforming the honeycomb core, ensuring accurate shaping and reducing the risk of defects, while maintaining the integrity of the panel's structure.
Implementation Method 1
shaping the heated panel to at least partially conform to the outer surface by pressurizing fluid within the pressure vessel. The pressurized fluid may force at least a portion of the second skin radially inward against the outer surface causing the heated panel to at least partially conform to the outer surface
Implementation Method 2
heating the panel. The pressurized fluid may force at least a portion of the second skin radially inward against the outer surface causing the heated panel to at least partially conform to the outer surface
Data Source
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AI summary
A manufacturing process is provided that includes arranging a tubular body with a mandrel. The tubular body circumscribes an outer surface of the mandrel and includes a panel and a sheet. The panel includes a porous first skin, a second skin and a cellular core between and connected to the porous first skin and the second skin. The sheet is configured with the second skin to form a pressure vessel. The first skin and the cellular core are located within the pressure vessel. At least a portion of the outer surface comprises an axially convex geometry. The panel is heated. The heated panel is shaped to at least partially conform to the outer surface by pressurizing fluid within the pressure vessel.