Expandable Mandrel for Composite Curing Support
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Solution Overview
Problem
Existing mandrel systems for curing composite parts are not suitable for out-of-autoclave processes, as inflatable bladders used in autoclave curing may not perform effectively under different temperature and pressure conditions, potentially impacting the final part characteristics.
Innovation Solution
A mandrel system comprising a housing with expandable components and an actuator that allows the mandrel to conform to internal part geometries during curing and reduce in size for easy removal, featuring a central opening with an expander that increases in width along its length, enabling the mandrel to expand and collapse for support and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inflatable bladder is used to support composite parts during autoclave curing, then the part geometry is properly maintained under autoclave pressure, but the bladder may not perform properly under out-of-autoclave temperature and pressure conditions
Solution Approach 1:
The mandrel uses an expandable housing structure with multiple components that can be moved relative to each other. The components include a first component, second component, third component, and fourth component that can expand the housing from a compressed state to an expanded state, allowing the mandrel to adapt its shape and size dynamically based on the curing process requirements and part geometry
Solution Approach 2:
The mandrel system changes its physical parameters (volume, shape, dimensions) by transitioning between compressed and expanded states. This parameter change capability allows the same mandrel to function effectively in different curing processes (autoclave and out-of-autoclave) and accommodate various part geometries
2Strength
If a rigid support tool is used to maintain part geometry, then structural support is provided during curing, but the tool cannot be easily removed from the part
Solution Approach 1:
The mandrel transitions from a static rigid structure to a dynamic expandable/collapsible structure. During curing, the housing is in an expanded state providing rigid structural support. After curing, the housing can be collapsed by retracting the expander, reducing the mandrel size to enable easy removal from the finished part
Solution Approach 2:
The mandrel components are designed to nest within each other when collapsed. The first, second, third, and fourth components can be positioned inside the housing when retracted, creating a compact nested configuration that facilitates removal from the cured part
3Shape
If a supporting bladder is inflated to fit internal cavity geometry, then the bladder conforms to the cavity shape, but the bladder cannot be easily removed after curing
Solution Approach 1:
The mandrel housing can expand to conform to the internal cavity geometry during curing, then collapse to a reduced size for easy removal. This dynamic shape change capability eliminates the removal difficulty associated with traditional inflatable bladders that maintain their expanded shape after curing
Solution Approach 2:
The mandrel is inserted in a compressed state into the internal cavity, then expanded to conform to the cavity geometry before curing begins. This preliminary expansion action allows the mandrel to achieve proper geometric conformance while maintaining ease of removal through subsequent collapse
Data Source
AI summary
Example mechanical supports or mandrels are described for composite part curing. In one example, a mandrel includes a housing, and components within the housing and positioned to create a central opening. An expander is also positioned in the central opening, and the expander has a width that increases along a length of the expander. A narrow end of the expander is positioned in the central opening. An actuator is provided to move the expander into the central opening causing the components to expand the housing, and to retract the expander from the central opening causing the components to collapse the housing.