Thermoplastic Composite Consolidation via Segmented Vacuum
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing thick composite panels with thermoplastic matrices, such as those used in aeronautics, face challenges in achieving adequate compaction and consolidation, leading to high porosity and increased scrap rates when the panel thickness exceeds 10 mm, due to inefficient gas removal and uneven pressure distribution.
Innovation Solution
A device and method utilizing containment blocks with grooves and a flexible compacting plate, combined with a sealed vacuum system, allow for effective gas removal through the perimeter of the panel stack, ensuring even pressure and preventing defects like porosity and corrugations, by applying two levels of vacuum pressure during the heating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vacuum is applied to compact and consolidate thick composite panels using the prior art method, then the panel can be manufactured without autoclave equipment, but the porosity rate becomes incompatible with structural aeronautic applications when panel thickness exceeds 10 mm
Solution Approach 1:
The vacuum application is segmented into two distinct phases: a first vacuum level applied during heating to remove gases before polymer melting, and a second higher vacuum level applied after melting to compact the panel. This segmentation allows each vacuum phase to address specific consolidation challenges at different stages of the process, enabling thick panel manufacturing with acceptable porosity rates without requiring autoclave equipment.
Solution Approach 2:
The first vacuum phase is applied as a preliminary action during the heating stage, before the thermoplastic polymer melts. This preliminary gas removal prevents excessive porosity from forming during the subsequent melting and consolidation phases, preparing the panel structure for effective compaction in the second vacuum phase.
2Manufacturing precision
If high vacuum pressure is applied to remove gas from thick panels, then porosity is reduced, but uneven pressure distribution causes corrugations and manufacturing defects
Solution Approach 1:
The vacuum pressure is made dynamic by applying two different vacuum levels at different stages of the process. The first vacuum level (lower negative pressure) is applied during heating when the polymer is still solid, and the second vacuum level (higher negative pressure) is applied after melting. This dynamic adjustment allows effective gas removal without applying excessive pressure that would cause corrugations in the plies.
Solution Approach 2:
The vacuum pressure parameter is changed between two distinct phases: a first negative pressure value during heating and a second negative pressure value (higher magnitude) during consolidation. This parameter change optimizes gas removal efficiency while preventing pressure-induced defects such as corrugations and ply squeezing.
3Strength
If thick panels with over 150 reinforcing plies are manufactured, then structural strength for aeronautic applications is achieved, but gas removal becomes inefficient leading to high scrap rates
Solution Approach 1:
The consolidation process is segmented into two vacuum phases that address different aspects of gas removal in thick panels. The first phase removes gases generated during heating before the polymer melts, while the second phase removes remaining gases during consolidation. This segmented approach makes gas removal efficient enough to produce defect-free thick panels with over 150 plies, significantly reducing scrap rates while maintaining the required structural strength.
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 approach enables optimal compaction and consolidation of thick composite panels, reducing porosity and scrap rates, and allowing for the production of high-strength panels suitable for structural aeronautic applications with improved mechanical characteristics and reduced manufacturing costs.
Implementation Method 1
means to apply vacuum to the volume wrapped in that manner comprising a plurality of holes in the board, wherein said plurality comprises holes that open outside the perimeter of the stack
Implementation Method 2
raising the temperature of the whole to the melting temperature of the polymer making up the matrix
Data Source
AI summary
A device for compacting and consolidating a stack of fibrous plies pre-impregnated with a thermoplastic polymer, configured to be placed in an oven. The device comprises containment blocks, a flexible compacting plate and a vacuum pump. The containment blocks are supported by a board and demarcate the perimeter of the stack. The containment blocks comprise open grooves that open into the perimeter of the stack. The flexible compacting plate has an area equal to that of the stack but is capable of being inserted inside the perimeter demarcated by the containment blocks. The vacuum pump applies a vacuum to the wrapped volume of the stack comprising a plurality of holes in the board that open outside the perimeter of the stack. A method for implementing the device for manufacturing a thick composite panel having a thermoplastic matrix.