Deformable Vehicle Seat Bars with Variable Wall Thickness
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Solution Overview
Problem
Vehicle seats, particularly aircraft seats, face a dilemma in requiring both flexibility for displacement tests and rigidity for force tests, with existing solutions being burdensome due to conflicting properties needed for these tests.
Innovation Solution
The design incorporates front and rear bars with varying rigidity, where central parts are more flexible and end parts are more rigid, achieved through tubular sections with reduced thickness and increasing thickness from the outside to the central part, using materials like deformable plastics, metals, or composite materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the seat structure is made rigid to pass the imposed force test, then the resistance to imposed force improves, but the resistance to imposed displacement deteriorates because the structure cannot deform sufficiently
Solution Approach 1:
The bars are designed with non-uniform thickness: thicker at the ends (for rigidity during force tests) and thinner at the central parts (for flexibility during displacement tests). This local variation in geometric properties allows each bar to simultaneously satisfy both conflicting test requirements.
Solution Approach 2:
The bars are segmented into distinct zones with different thickness characteristics. The end parts have increased thickness to provide rigidity, while the central parts have reduced thickness to provide flexibility. This segmentation allows the single bar component to exhibit different mechanical properties in different regions.
2Adaptability or versatility
If the front and rear bars are designed with large diameter and small thickness to achieve flexibility, then the resistance to imposed displacement improves, but the resistance to imposed force deteriorates
Solution Approach 1:
Instead of using a uniform thin-walled tube throughout, the invention applies local quality by varying the wall thickness along the bar length. The thicker end sections provide the necessary strength and rigidity, while the thinner central sections provide the required flexibility and deformability.
Solution Approach 2:
The geometric parameter (wall thickness) of the tubular bars is changed along their length. By increasing thickness at the ends and decreasing it at the center, the mechanical properties (rigidity and flexibility) are optimized for different functional requirements at different locations.
3Ease of manufacture
If uniform thickness bars are used, then the manufacturing simplicity improves, but the overall weight increases due to the need to satisfy both conflicting test requirements
Solution Approach 1:
The invention applies local quality by varying the wall thickness along the bar length. The thicker end sections provide the necessary strength and rigidity, while the thinner central sections provide the required flexibility and deformability.
Solution Approach 2:
The geometric parameter (wall thickness) of the tubular bars is changed along their length. By increasing thickness at the ends and decreasing it at the center, the mechanical properties (rigidity and flexibility) are optimized for different functional requirements at different locations.
Data Source
AI summary
The invention relates to a vehicle seat, preferably multiple-seater, which is deformable at the centre thereof and makes it possible to respond to deformation stresses in the event of an accident, impact or crash. In the case of a three-seater seat, the seat is primarily formed by four legs (10), a central seat portion (12), two end seat portions (11) and three backrests (13). The seat portions are bordered by two side bars (18) and one front bar and one rear bar. The front and rear bars are each formed by a central bar (14) or (16) which is extremely flexible, while the end bars (15, 17) of the end seats (11) are extremely rigid. The invention can also be used in aircraft seats.