Thermoplastic Tape Placement Head with Conformable Compactors
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Solution Overview
Problem
Current methods for applying thermoplastic tape to complex aerospace structures, such as aircraft wings and fuselages, are inefficient and require an autoclave for curing, which is not feasible for large singly-curved or doubly-curved composite structures.
Innovation Solution
An automated thermoplastic in situ tape placement head with conformable compactors that includes a heated zone for preheating and a chilled zone for curing, using movable members and shims to apply and consolidate thermoplastic tape without direct contact, allowing for out-of-autoclave fabrication of complex geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an autoclave is used for curing thermoplastic tape, then the tape can be properly cured and bonded, but the process becomes impractical for large singly-curved or doubly-curved composite structures
Solution Approach 1:
The autoclave curing process is segmented into two distinct zones: a heated zone for softening and bonding the thermoplastic tape, and a chilled zone for curing and solidifying it. This segmentation allows the process to adapt to complex curved geometries while maintaining proper curing, as each zone can be independently controlled and positioned along the tape path.
Solution Approach 2:
The heated zone performs preliminary action by softening the thermoplastic tape before it reaches the curing zone. This preliminary heating and softening enables the tape to conform to the substrate geometry and bond properly, while the subsequent chilled zone completes the curing process, eliminating the need for a traditional autoclave.
2Force
If the feet of the compactor directly contact the thermoplastic tape, then effective compaction and bonding can be achieved, but the tape may be damaged by direct contact
Solution Approach 1:
A shim is introduced as an intermediary element between the compactor feet and the thermoplastic tape. The shim transmits the compaction force from the feet to the tape while protecting the tape from direct contact and potential damage. This allows effective bonding force to be applied without the harmful effects of direct mechanical contact.
3Stability of the object's composition
If the feet are made rigid for stable compaction, then consistent bonding pressure is achieved, but the compactor cannot conform to curved surfaces
Solution Approach 1:
The compactor feet are designed to be independently movable rather than rigidly fixed. Each foot can adjust its position dynamically to conform to the local geometry of the substrate while maintaining consistent bonding pressure. This dynamic adaptability allows the compactor to handle both flat and complex curved surfaces effectively.
4Temperature
If the bladder in the heated compactor area is exposed to high heat, then the heating function is effective, but the bladder may melt and fail
Solution Approach 1:
A thermal break is introduced as a protective intermediary between the heated compactor area and the bladder. This thermal break prevents excessive heat from reaching the bladder while allowing the heating function to remain effective for the thermoplastic tape. The thermal break protects the bladder from melting while maintaining the necessary heating temperatures for the process.
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, out-of-autoclave fabrication of large, complex composite structures by maintaining the tape in a heated state for bonding and using conformable compactors to adapt to curved surfaces, eliminating the need for an autoclave and ensuring precise tape application.
Implementation Method 1
a heated area compactor having a plurality of movable heated members or feet that would be moved toward the tape and would maintain the tape in a heated condition so as to press the heated tape against the object
Implementation Method 2
A chilled area compactor is in a chilled zone disposed downstream and also includes a plurality of movable members or feet which, however, are at a chilled temperature so as to cure the tape
Implementation Method 3
the feet are moved toward the shims by an air cylinder which presses a reservoir housing against a conformable bladder thereby causing the bladder to press against the feet
Data Source
AI summary
A tape placement head for applying thermoplastic tape to an object includes a heated feeder which guides the tape/tow to a heated zone. The heated zone has a line compactor having a single row of at least one movable heated member. An area compactor is located in the heated zone downstream from the line compactor. The area compactor includes a plurality of rows of movable feet which are extendable toward the tape/tow different distances with respect to each other to conform to the shape of the object. A shim is located between the heated compactors and the tape/tow. A chilled compactor is in a chilled zone downstream from the heated zone. The chilled zone includes a line chilled compactor and an area chilled compactor. A chilled shim is mounted between the chilled compactor and the tape/tow.