Yieldable Fastener for Vehicle Seat Backboard Attachment
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Solution Overview
Problem
Vehicle seating systems often fail to maintain attachment between the seat-back frame and backboard during impact events like rear-end collisions due to the inability of rigid fasteners to yield under separation forces.
Innovation Solution
Incorporating an elongated member with a yield strength of no more than 185 MPa, configured to plastically deform and maintain attachment between the seat-back frame and backboard when subjected to separation forces between 432 N and 1602 N, thereby absorbing energy and preventing connection failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid fasteners are used to attach the backboard to the seat-back frame, then the connection strength is high under normal conditions, but the attachment fails under separation force during impact events
Solution Approach 1:
The patent changes the mechanical parameter of the fastener from rigid to yieldable by specifying a yield strength between 105-185 MPa and a yield strain of 0.005-0.015. This allows the fastener to deform plastically under impact forces, absorbing energy while maintaining attachment, thus resolving the contradiction between high connection strength and reliability under impact.
Solution Approach 2:
The patent implements beforehand cushioning by designing the fastener with controlled yield characteristics that activate before catastrophic failure. The yieldable fastener acts as a pre-designed energy absorption mechanism that engages during impact events, cushioning the system against the full force of separation while maintaining the attachment between backboard and seat-back frame.
2Reliability
If the fastener yield strength is increased to maintain attachment under separation force, then the attachment reliability improves, but the fastener cannot yield to absorb impact energy
Solution Approach 1:
The patent optimizes the fastener strength parameter to a specific range (105-185 MPa yield strength) that balances two opposing requirements: being strong enough to maintain attachment reliability under impact, yet weak enough to yield and absorb impact energy. This precise parameter control resolves the contradiction between reliability and energy absorption capability.
3Ease of manufacture
If rigid attachment connections are used, then the manufacturing precision is high, but the system cannot accommodate deformation during impact events
Solution Approach 1:
The patent transforms the static rigid connection into a dynamic system where the fastener can change its mechanical state. The yieldable fastener transitions from an elastic state during normal operation to a plastic deformation state during impact, allowing the system to adapt to impact forces while maintaining manufacturability through standard fastening processes.
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 elongated member ensures the backboard remains attached to the seat-back frame by plastically deforming under high separation forces, reducing the stress on connection features and maintaining the attachment even when forces exceed the initial connection strength, thus enhancing safety during collisions.
Implementation Method 1
The elongated member may be configured to plastically deform such that the backboard remains attached to the seat-back frame and the backboard when the seat-back frame and the backboard are subjected to a separation force
Data Source
AI summary
A seating system for a vehicle includes a seat-back frame and a backboard attached to the seat-back frame. An attachment arrangement includes an elongated member attached to the seat-back frame and the backboard, and is configured to remain attached to the seat-back frame and the backboard by plastically deforming when the seat-back frame and the backboard are subjected to a separation force of a predetermined magnitude greater than a magnitude otherwise required to detach the elongated member from the backboard.