Tensioned Stringer Fabrication via Segmented Charges
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Solution Overview
Problem
Existing methods for forming composite blade stringers from a single flat laminate restrict independent movement of facing sides and the creation of localized geometrical features, leading to anomalies and uneven tension within the stringer.
Innovation Solution
The method involves using two separate charges, each positioned with a first section over a die cavity and a second section secured away, allowing independent tensioning along their lengths during the forming process, enabling independent fiber movement and reducing wrinkles by using a tooling assembly with form blocks and a punch die to shape the stringer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single flat laminate is used to form the stringer, then the manufacturing process is simpler, but the facing sides cannot move independently during formation causing anomalies and wrinkles
Solution Approach 1:
The single flat laminate is divided into two separate charges, each with its own blade and flange sections. This segmentation allows each charge to move and form independently during the punching process, eliminating the anomalies and wrinkles that occur when a single laminate is forced into the die cavity while maintaining manufacturing simplicity.
2Device complexity
If a single laminate charge is used, then the device complexity is reduced, but the ability to create localized geometrical features on each side is restricted
Solution Approach 1:
By dividing the laminate into two separate charges, each charge can be independently formed with different localized geometrical features. The first charge can have features on its first facing side while the second charge has features on its first facing side, enabling greater design versatility without significantly increasing overall device complexity.
3Manufacturing precision
If the second sections of the laminate remain out of the die cavity during punching, then the first section can be formed, but the second sections are not in tension leading to uneven tension distribution
Solution Approach 1:
The tensioning system is segmented to work with separate charges. Each charge's second section is secured away from the die cavity while the first section is formed, creating tension in each charge independently. This segmented approach ensures uniform tension distribution across both charges, preventing the uneven tension that occurs with a single laminate design.
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 allows for the formation of stringers with reduced wrinkles and the ability to create non-symmetric, geometrically complex designs, facilitating the use of different materials and geometries, thereby enhancing the quality and versatility of the stringer fabrication process.
Implementation Method 1
The punch die drives the first ends of the first and second charges into the die cavity while the second ends remain secured away from the die cavity. Tensioning the charges along their lengths
Data Source
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AI summary
Methods and devices of fabricating a stringer for a vehicle. The stringer can be constructed from two charges that are formed together into the stringer. During fabrication, the charges are placed over support members with the ends of each charge extending over a die cavity. The charges are secured and a punch die forces the first ends into the die cavity forming blades of the stringer. The charges are secured thus tensioning the charges during the punch process.