Aircraft Sheet Butt-Joint Reinforcement for Fatigue Reduction
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Solution Overview
Problem
Conventional rivet connections in aircraft metal sheets require time-consuming and costly material removal to create thickened regions for stress reduction, leading to material fatigue and inadequate static and damage-tolerance characteristics.
Innovation Solution
A method involving butt-joint connections with mechanical and chemical adhesive pre-treatment, and the application of reinforcement elements wider than the joining region to create an additional load path, eliminating the need for material removal and enhancing adhesion and mechanical loading capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If material removal is performed outside the seam area to produce thickened regions, then seam stress is reduced and material fatigue is mitigated, but production time and cost increase significantly
Solution Approach 1:
The method performs adhesive pre-treatment (mechanical and/or chemical) on the sheet-like formations and joining region before the actual joining process. This preliminary preparation enables the subsequent application of reinforcement elements to effectively reduce seam stress and prevent material fatigue without requiring time-consuming material removal operations.
Solution Approach 2:
Reinforcement elements are introduced as intermediary components between the sheet-like formations. These elements serve as mediators that distribute and reduce seam stress, preventing material fatigue while avoiding the need for material removal. The reinforcement elements create an additional load path that enhances the overall connection reliability.
2Reliability
If material removal is performed to create thickened regions, then seam stress is reduced, but production cost increases due to expensive processing operations
Solution Approach 1:
The method extracts the stress-reduction function from the traditional approach of material removal and transfers it to reinforcement elements. Instead of removing material to create thickened regions, reinforcement elements are applied to the joining region to achieve the same stress-reduction effect at lower cost.
Solution Approach 2:
The method changes the approach from modifying the geometric parameters of the base material (through removal) to adding reinforcement elements with specific width parameters. The reinforcement elements have a width wider than the joining region width, creating adequate overlap and an additional load path that reduces seam stress without requiring expensive material removal operations.
3Ease of manufacture
If conventional rivet connections are used, then metal sheets can be joined, but the connection lacks additional load paths and has inadequate damage-tolerance characteristics
Solution Approach 1:
The method creates a composite connection structure by combining the base metal sheets with reinforcement elements through adhesive bonding. This composite construction provides multiple load paths, including the primary joining region and the additional load path created by the reinforcement elements, thereby enhancing damage-tolerance characteristics while maintaining ease of manufacture.
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 reduces material fatigue and improves static and damage-tolerance characteristics by creating an additional load path without the need for costly material removal, while maintaining the structural integrity of the connection.
Implementation Method 1
an additional load path is created as a result of the connection of both sheet-like formations
Implementation Method 2
the mechanical stress (in the seam region) is now reduced by pasting-on at least one reinforcement element
Implementation Method 3
mechanical and/or chemical adhesive pre-treatment of the sheet-like formations and/or of the joining region
Implementation Method 4
As a result of the mechanical and/or chemical adhesive pre-treatment of the sheet-like formations and/or of the joining regions, improved adhesion of the at least one pasted on reinforcement element is achieved
Implementation Method 5
the material thickness of the joining region after mechanical processing to be less than, or equal to, the material thickness of the sheet-like formations
Data Source
AI summary
A method for connecting at least two sheet-like formations, in particular at least two metal sheets with a thin material thickness for aircraft, comprises establishing butt-joint connections between the sheet-like formations by forming a joining region; mechanical processing of the sheet-like formations and/or of the joining region; mechanical and/or chemical adhesive pre-treatment of the sheet-like formations and/or of the joining region; and pasting-on at least one reinforcement element in the region of the top and/or the bottom of the joining region, wherein for the purpose of forming a second load path the width of the at least one reinforcement element is wider than the width 16 of the joining region. A connection is provided and made according to the method. A lightweight structure is also provided that comprises at least one connection according to the invention.