Partially Cured Sublaminate Units for Composite Manufacturing
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Solution Overview
Problem
Traditional methods for manufacturing thermoset composite articles, such as those used in aircraft structures, are costly due to the need for expensive autoclaves and specialized equipment, and require extended processing times, which complicates high-volume production and increases manufacturing costs.
Innovation Solution
The method involves standardizing composite pre-preg materials into partially cured sublaminate units, which are then stacked, bonded, and cured in stages using intermediate and final temperatures to achieve a high degree of cure, reducing the need for large equipment and specialized tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional autoclave processing is used to cure composite layups, then the composite article achieves necessary mechanical properties, but the processing time is extended up to 24 hours and equipment costs are high
Solution Approach 1:
The patent divides the composite structure into multiple sublaminate units that can be cured independently to a lower degree of cure (30-70%), then stacked and bonded together. This segmentation allows parallel processing of multiple units simultaneously, dramatically reducing total production time while maintaining structural integrity through the bonding of cured interfaces.
Solution Approach 2:
The patent applies preliminary curing to sublaminate units before final assembly, achieving a degree of cure of 30-70% in advance. This preliminary action allows the materials to be prepared, stacked, and bonded in advance, then completed with a final cure cycle that achieves full mechanical properties without requiring 24 hours of continuous autoclave processing.
2Reliability
If traditional autoclave processing and specialized equipment are used, then composite articles achieve required quality, but manufacturing costs increase significantly
Solution Approach 1:
The patent segments the manufacturing process into independent sublaminate production and final assembly stages. Each sublaminate can be cured to 30-70% degree of cure using less expensive equipment, then stacked and bonded together. This eliminates the need for expensive large-capacity autoclaves and specialized tooling required for traditional full-cure processing of large structures.
Solution Approach 2:
The patent employs sacrificial release films and bonding interfaces that allow for simpler, less expensive tooling. The release films enable easy separation of sublaminate units during processing, and the bonding interfaces are designed to create strong joints without requiring expensive specialized equipment, thereby reducing overall manufacturing costs while maintaining quality.
3Adaptability or versatility
If thin plies of pre-preg are used for primary structure, then composite optimization is achieved, but automated fiber placement equipment becomes very expensive and processing time increases to days
Solution Approach 1:
The patent groups multiple thin plies into sublaminate units of optimized thickness that can be processed as discrete components. These pre-consolidated sublaminate units can be manufactured using more economical equipment and then assembled into the final structure, avoiding the need for expensive automated fiber placement equipment to lay up each individual thin ply sequentially over days.
Solution Approach 2:
The patent performs preliminary consolidation of multiple plies into sublaminate units with optimized fiber architecture and resin distribution before final assembly. This preliminary action allows for better material optimization and reduced processing time, as the sublaminate units are pre-prepared with correct stacking sequences and can be rapidly assembled and cured to completion.
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 simplifies the manufacturing process, reduces costs by eliminating the need for expensive equipment, and allows for faster production of composite parts with improved mechanical properties.
Implementation Method 1
heating the stack of sublaminate units to an intermediate temperature above a glass transition temperature of the resin for a time interval sufficient to intermediately cure the resin to an intermediate cure stage of 50% to 70% of full cure
Implementation Method 2
finally curing the resin in the composite laminate at a final temperature higher than the intermediate temperature to a final cure stage
Data Source
AI summary
A method of forming a composite article. One step involves applying adhesive on surfaces of a plurality of sublaminate units, each ply of each sublaminate unit comprising fibers impregnated with resin which has been initially cured to 30% to 50% of full cure. The initially cured sublaminate units are then arranged in a stack, which stack is pressed against a surface of a forming tool. While pressure is being applied, the stack is heated to an intermediate temperature above a glass transition temperature of the resin for a time interval sufficient to intermediately cure the resin to 50% to 70% of full cure to form a composite laminate having a contour defined by the surface of the forming tool. Then the resin is finally cured at a final temperature higher than the intermediate temperature.