Prestressing Flange for Energy-Absorbing Element
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Solution Overview
Problem
Existing energy-absorbing elements, such as those described in document EP 2113677, do not effectively maintain prestress, which limits their performance in applications like helicopter seats under varying stress conditions.
Innovation Solution
Incorporating a prestressing flange between the distal ends of the energy-absorbing element, with a length greater than the gap between them, to maintain prestress, and positioning it along the axis of symmetry, with thickness adjusted for compression forces and length tailored to the required prestress level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no prestressing flange is used, then the device complexity is low, but the energy-absorbing element cannot maintain prestress and has limited performance under varying stress conditions
Solution Approach 1:
The flange is installed between the distal ends of the energy-absorbing element to apply a preliminary prestressing force that maintains the element in a prestressed state during operation. This preliminary action ensures the element is pre-loaded to optimal tension, improving its performance and reliability under varying stress conditions without requiring complex active control systems
2Reliability
If the flange length is increased to maintain prestress, then the prestress maintenance capability improves, but the device complexity and material usage increase
Solution Approach 1:
The flange length is specifically designed to be greater than the gap between the distal ends of the energy-absorbing element. This parameter optimization allows the flange to effectively maintain prestress by spanning the gap and applying compressive force, while avoiding excessive material usage. The thickness of the flange is also optimized as a function of the compression forces exerted by the absorbent portion
3Stability of the object's composition
If the flange is positioned along the axis of symmetry, then the structural stability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The flange is positioned along the axis of symmetry of the energy-absorbing element, which inherently provides structural stability and balanced force distribution. This symmetric positioning simplifies the manufacturing process by allowing the use of symmetric tooling and fixtures during installation, thereby reducing the actual positioning precision requirements despite the symmetric 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
The prestressing flange enhances the energy-absorbing element's performance by maintaining its prestressed state, improving its ability to handle tensile stresses and preventing buckling under compression forces, thereby enhancing its operational effectiveness in applications like helicopter seats.
Implementation Method 1
the thickness of the flange is a function of the compression forces exerted by the absorbent portion on the flange
Implementation Method 2
deforming elastically during a tensile stress below a predetermined threshold
Implementation Method 3
plastically during a tensile stress greater than said predetermined threshold
Data Source
Figure 1~2
Figure 3
AI summary
The invention essentially relates to an energy-absorbing element (1) comprising: an absorbing portion (2), a first (3) and second anchoring point (4), a first (2) and second (2) distal ends of said absorbing portion (2) being respectively secured to the first and second anchoring points (3, 4), characterized in that it also comprises: a pretensioning flange (12) installed between the first (2) and second (2) distal ends, the length (L) of said flange (12) exceeding the gap (E) between the two distal ends (2, 2) in order to pretension said absorbing element.