Composite Stringer Mould Segmentation for Complex Geometry
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Solution Overview
Problem
Current methods for manufacturing composite aircraft stringers with complex shapes, such as omega sections with thickness changes, longitudinal deflection, and torsion, are inadequate as they often result in wrinkles and malformation due to the inability to adapt traditional mould-and-plate machines to non-straight stringers.
Innovation Solution
An apparatus comprising a male mould, a main caul plate, fixed and movable female mould halves, secondary caul plates, and retention means that allow for controlled pressure and temperature management, enabling the formation of composite stringers with complex geometries by maintaining a predetermined gap and applying pressure to prevent laminate separation and ensure free sliding during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If traditional mould-and-plate machines are used to manufacture composite stringers, then the manufacturing process is simple, but the stringers cannot achieve complex geometries such as omega sections with thickness changes, longitudinal deflection, and torsion
Solution Approach 1:
The manufacturing apparatus is segmented into multiple independent mould halves (first and second mould halves) and multiple caul plates (first and second caul plates), each capable of independent movement. This segmentation allows the apparatus to accommodate complex geometries by forming different sections of the stringer simultaneously in separate mould cavities, while maintaining manageable device complexity through modular design
Solution Approach 2:
The apparatus employs dynamic elements including movable mould halves and adjustable caul plates that can be positioned at different locations along the stringer length. This dynamics enables the manufacturing of stringers with varying thickness, curvature, and torsion by adjusting the position and shape of mould surfaces during the forming process
2Manufacturing precision
If traditional methods are used to manufacture non-straight stringers, then the manufacturing process is simple, but wrinkles and malformation occur
Solution Approach 1:
The retention means are positioned and configured in advance to engage with the laminate at critical locations before the forming process begins. This preliminary action prevents wrinkles and malformation by maintaining proper laminate tension and position throughout the forming process, ensuring high manufacturing precision without requiring complex real-time control systems
Solution Approach 2:
The retention means act as intermediary elements between the mould halves and the laminate, providing controlled restraint that prevents laminate separation and wrinkle formation. These retention means include retention blocks and retention means that mediate the interaction between the forming apparatus and the composite material, ensuring surface quality
3Shape
If complex geometries are manufactured with traditional apparatus, then the stringer fitment in aircraft fuselage is accurate, but the manufacturing process cannot accommodate thickness changes and longitudinal deflection
Solution Approach 1:
The manufacturing apparatus is designed with universal features including adjustable caul plates, movable mould halves, and configurable retention means that can be adapted to manufacture various stringer geometries. This multi-functionality allows the same apparatus to produce stringers with different thickness variations, longitudinal deflections, and torsional shapes, greatly enhancing adaptability
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
The apparatus effectively manufactures composite stringers with complex geometries, preventing wrinkles and malformation, and ensuring accurate fitment in aircraft fuselage sections with double curvature and thickness variations, thereby enhancing the structural integrity and weight optimization of aircraft components.
Implementation Method 1
the female mould halves comprise heating means suitable for heating the composite laminate within a controlled and registered cycle
Implementation Method 2
the retention means are blocks adapted to retain the secondary movable caul plates, creating a predetermined gap always lower than about 2 mm between each secondary caul plate and the composite laminate to allow the free sliding of the composite laminate during the manufacturing process, but preventing said composite laminate from separating from the female mould halves
Data Source
AI summary
An apparatus for manufacturing composite stringers from a composite laminate comprising a male mold, a main caul plate, two fixed female mold halves, two secondary movable caul plates and a retention device. The main caul plate is located below the male mold, the female mold halves are located at both sides of the main caul plate and the secondary movable caul plates, each of them located respectively over each one of the two female mold halves. The male mold, the main caul plate, the two female mold halves and the two secondary caul plates are non-developable surfaces. The retention device keeps each secondary movable caul plate at a predetermined distance of its respective female mold half.