Barrel Structure Forming via Vacuum Infusion and Single-Stage Cure
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Solution Overview
Problem
Current methods for producing engine nacelle inner barrel structures are costly and time-consuming due to the use of pre-impregnated materials, multiple autoclave cures, and expensive core materials, which require subzero storage and have limited 'out-time', leading to constraints in manufacturing efficiency and cost.
Innovation Solution
A method involving a one-step cure process using dry fabrics and wax mandrels, where a vacuum bag is applied over a steel mold tool, resin is infused, and the structure is cured in an oven, with subsequent drilling and melting out of wax mandrels to form a unitized truss design with integral septum details, eliminating the need for autoclaves and reducing material storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pre-impregnated materials and multiple autoclave cures are used, then manufacturing precision and structural integrity are improved, but manufacturing time and cost increase significantly
Solution Approach 1:
The manufacturing process is segmented into distinct phases: dry fabric layup, resin infusion, and single-stage curing. This segmentation allows each phase to be optimized independently, reducing overall manufacturing time while maintaining structural integrity through controlled resin impregnation and curing sequences.
Solution Approach 2:
Dry fabrics are prepared and laid up in the desired configuration before resin infusion. Wax mandrels are pre-positioned to define core geometry. These preliminary actions enable efficient resin distribution and eliminate the need for multiple curing cycles, thereby reducing manufacturing time while ensuring precision.
2Manufacturing precision
If pre-impregnated materials are used, then manufacturing precision is improved, but material storage requirements and costs increase due to subzero storage needs
Solution Approach 1:
The resin is extracted from the pre-impregnated material state and applied separately through infusion. This separates the fabric storage requirement from the resin storage requirement, allowing fabrics to be stored dry at ambient conditions while resin is infused only when needed, eliminating subzero storage needs.
Solution Approach 2:
Dry fabrics replace expensive pre-impregnated materials that require controlled storage. The dry fabrics are stable, inexpensive to store, and can be kept indefinitely without degradation, eliminating the need for subzero storage infrastructure.
3Strength
If multiple autoclave cures are used, then structural integrity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
Multiple curing operations are merged into a single cure cycle. The resin formulation and processing parameters are optimized to achieve complete curing and structural consolidation in one autoclave cycle, eliminating the need for multiple separate curing operations and their associated setup, monitoring, and quality control steps.
Solution Approach 2:
The curing parameters (temperature, pressure, time profile) are optimized and adjusted to enable single-stage curing that achieves the same structural integrity as multiple cures. This parameter optimization reduces process complexity while maintaining strength requirements.
4Strength
If expensive core materials are used, then structural performance is improved, but manufacturing cost increases
Solution Approach 1:
Wax mandrels replace expensive core materials. The wax mandrels are inexpensive, easily formed, and serve their purpose during resin infusion and curing. After curing, the wax mandrels are melted out and discarded, having served their temporary function of defining core geometry without requiring expensive recovery or reuse infrastructure.
Solution Approach 2:
The wax mandrels are deliberately discarded after serving their geometric definition purpose. The melting and removal process is simple and low-cost, avoiding the need for expensive core material recovery or reuse systems while maintaining structural performance through proper resin infusion around the mandrel-defined geometry.
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 reduces manufacturing time and cost by using a single oven heat cycle, eliminates the need for subzero storage, and provides a robust, single-joint interface for the inner barrel structure, improving efficiency and reducing material expenses.
Implementation Method 1
vacuum bag is installed over a dry three-dimensional preform inner barrel structure... vacuum pressure... infusing the dry three-dimensional preform inner barrel structure with resin
Implementation Method 2
curing the resin-infused inner barrel structure to form an inner barrel... places the inner barrel with the number of holes in the oven... melting out a number of wax mandrels from the inner barrel through the number of holes drilled
Implementation Method 3
melting out a number of wax mandrels from the inner barrel through the number of holes drilled
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A method of forming a barrel structure (1000), the barrel structure being usable for an engine nacelle. The method comprises the installation of a vacuum bag over a three dimensional preform of a barrel structure. on a mold (2202), placing the preform inside an oven (2204), infusing resin (2206), curing (2208) and removing steps (2210, 2212, 2216) as well as drilling holes in the inner and outer barrel skin (2218).