Vacuum Film Segmentation for Aircraft Stringer Joining
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Solution Overview
Problem
The existing methods for joining I-shaped stringers to panel elements in aircraft rudder units are cumbersome due to the complexity of laying vacuum films over the step formed by the stringers, requiring manual finishing and mechanical stress, which complicates the process and increases errors.
Innovation Solution
A method involving a two-step vacuum arrangement where covering vacuum films match the stringer contours and vacuum film strips span the intermediate spaces between stringers, allowing for automated application and reduced mechanical stress, with the option of precured stringers forming part of the vacuum arrangement and using flow fabrics for resin distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional mechanical film laying apparatuses are used to press vacuum films onto the vertical profile of the step formed by I-shaped stringers, then the vacuum film can be applied to the stringer surface, but the low height of the step corresponding to the wall thickness of the stringers is not sufficient to press the film onto the vertical profile, requiring complicated manual finishing operations
Solution Approach 1:
The vacuum film application process is segmented into two distinct stages: first, covering vacuum films are applied to the stringers themselves, and second, vacuum film strips are applied to the intermediate spaces between stringers. This segmentation allows each type of film to be optimized for its specific application area, eliminating the need for complex manual finishing operations while maintaining ease of operation.
2Manufacturing precision
If vacuum films are laid with positive fit over the step formed by I-shaped stringers, then complete coverage is achieved, but the process becomes complicated and requires manual finishing operations
Solution Approach 1:
The vacuum arrangement is divided into covering vacuum films that precisely fit individual stringers and vacuum film strips that cover intermediate spaces. This segmentation achieves complete coverage with manufacturing precision while simplifying the application process through specialized apparatuses designed for each component type.
Solution Approach 2:
Vacuum film strips serve as an intermediary element that bridges the intermediate spaces between stringers, allowing the vacuum arrangement to be completed without requiring complex manual operations on the stringer surfaces themselves. The strips are applied separately and connect the edge regions of adjacent stringers.
3Reliability
If the vacuum film is pressed onto the vertical profile of the step with sufficient pressure, then the film adheres properly, but mechanical stresses occur and the process becomes complicated
Solution Approach 1:
The vacuum film system is segmented into covering vacuum films for stringers and vacuum film strips for intermediate spaces. This allows each component to be pressed with appropriate pressure independently, ensuring reliable adhesion without requiring complex high-pressure apparatuses that would generate excessive mechanical stresses.
Solution Approach 2:
The use of flexible vacuum film strips to cover intermediate spaces allows the films to conform to the geometry without requiring excessive pressing pressure. The flexibility of the thin film material enables proper adhesion through minimal pressure, reducing mechanical stresses and apparatus complexity.
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 method simplifies the joining process, reduces manual intervention, minimizes errors, and allows for automation, thereby shortening production time and reducing manufacturing costs while accommodating various stringer profiles and configurations.
Implementation Method 1
A vacuum arrangement required for the joining operation is produced in two parts. In a first step, individual stringers are covered in advance with covering vacuum films. The stringers prepared in this manner are arranged on a structural component. In a second step, vacuum film strips are arranged on adjacent stringers and over an intermediate space between the adjacent stringers.
Data Source
AI summary
The invention relates to a method for joining cured stringers to at least one structural component of an aircraft or spacecraft, including placing the stringers onto the at least one structural component, depositing and pressing respective vacuum film strips such that each strip is attached to a pair of stringers and present between the pair of stringers with the use of vacuum sealing means in such a manner that a continuous vacuum arrangement, comprising the covering vacuum films and the vacuum film strips, is formed, and pressurized joining of the stringers to the at least one structural component by means of the continuous vacuum arrangement formed.