Composite Stiffener Compaction Using Removable In-Tool Inserts
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Solution Overview
Problem
The compaction of out-of-plane features in composite structures, particularly in integrally stiffened structures, is difficult and often requires separate work cells, additional tooling, and high thermal processing, which can damage the preform and is costly.
Innovation Solution
The use of low-cost, tailored forming tools that can be inserted into a base mold tool to compact out-of-plane features, featuring inserts with non-adhesive layers to prevent adhesion and facilitate easy removal, allowing compaction in situ without the need for secondary operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high CTE tooling is used to impart compaction, then compaction of out-of-plane features is achieved, but the time and energy required to heat and cool the tool increases cost
Solution Approach 1:
The tooling is divided into a monolithic base tool and separate removable inserts. The inserts are specifically designed to provide compaction force only to the out-of-plane features (stiffeners), while the base tool provides the overall forming surface. This segmentation allows the inserts to be heated independently and removed without cooling the entire tool, significantly reducing cycle time.
Solution Approach 2:
The compaction function is extracted from the monolithic tool and placed into separate removable inserts. These inserts can be taken out after forming, eliminating the need to cool the entire tool for part removal. The inserts are heated separately to expand and provide compaction force, then removed while still hot, avoiding the cooling step entirely for the compaction elements.
2Manufacturing precision
If separate work cells with additional tooling are used, then compaction of out-of-plane features is achieved, but device complexity and cost increase
Solution Approach 1:
The compaction function for out-of-plane features is merged into the base mold tool through the use of inserts. Instead of requiring a separate work cell with additional tooling, the inserts are integrated into the base tool cavity, allowing compaction to occur in-situ during the same forming operation. This eliminates the need for separate equipment, floor space, and handling operations.
Solution Approach 2:
The base mold tool serves multiple functions: it provides the overall forming surface for the composite structure and simultaneously accommodates inserts that provide localized compaction force for out-of-plane features. The inserts themselves serve dual purposes by being heated to expand (providing compaction) and then serving as release agents to facilitate part removal.
3Ease of operation
If non-adhesive layers are added to inserts, then easy removal and flexibility are achieved, but manufacturing complexity increases
Solution Approach 1:
A thin non-adhesive film or coating is applied to the surface of the inserts that contact the preform. This thin layer prevents adhesion between the insert and the composite material, allowing for easy removal of the insert and the formed part. The film is thin enough that it does not significantly add to the manufacturing complexity or interfere with the compaction function.
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 efficient and cost-effective compaction of out-of-plane features within a mold tool, reducing the risk of preform damage and eliminating the need for separate work cells, while allowing for easy removal and flexibility in changing stiffener geometries without re-fabricating the entire tool.
Implementation Method 1
the insert has a non-adhesive layer to prevent adhesion and facilitate easy removal
Data Source
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AI summary
An in-tool system for compacting an out-of-plane feature (212) of a composite structure. The in-tool system comprises a cavity (214) formed in a tool (208), a stiffener preform (210), and an insert (230, 234). The cavity has an angled surface (218, 220). The stiffener preform includes an out-of-plane feature (212), where the out-of-plane feature has a compaction surface (222). The insert comprises a first face (204) complementary to the angled surface (218) of the cavity and a second face (232) complementary to the compaction surface (222) of the out-of-plane feature. The first face is opposite the second face.