Ski Boot Fairlead Stress Distribution Design
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Solution Overview
Problem
Existing ski boot designs face issues with stress concentration and cable exposure, leading to potential cracks, breaks, and reduced durability due to tensile and bending stresses on fairleads, especially during extreme use.
Innovation Solution
The introduction of a ski boot design featuring a fixed insert with a removable platelet that distributes stress over a larger area, housing the cable in a curved channel to reduce mechanical stress and protect it from shocks and frictions, while allowing for pre-assembly and differentiation of materials for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fairlead is fixed directly to the plastic of the foot portion or leg portion using screws or rivets, then the fixing is guaranteed, but considerable tensile stresses are discharged through shearing action on the screw or rivet, and mechanical stresses are concentrated in specific areas leading to cracks and breaks
Solution Approach 1:
The fairlead is divided into a fixed insert portion that remains attached to the boot and a removable platelet portion that can be detached. This segmentation allows the fixed insert to provide stable mounting while the removable platelet distributes stresses and protects the cable, resolving the contradiction between secure fixing and stress concentration.
Solution Approach 2:
The fixed insert acts as an intermediary element between the boot structure and the removable platelet. It provides a stable mounting base while allowing the platelet to be removed for repair or replacement, thus distributing stresses and preventing direct stress concentration on the boot plastic or fasteners.
2Ease of operation
If the cable turns around the fairlead with separated incoming and outgoing branches, then the fairlead guides the cable, but the cable is subjected to considerable mechanical stress due to small bending radius
Solution Approach 1:
The removable platelet features a curved channel that guides the cable in a smooth, large-radius curve rather than a sharp bend. This curvature reduces the bending stress on the cable while maintaining effective guidance, resolving the contradiction between cable routing functionality and cable strength preservation.
3Strength
If the fairlead is fixed at specific points of the leg portion or foot portion, then the mechanical connection is established, but considerable mechanical stresses are concentrated in those areas which can generate cracks and breaks
Solution Approach 1:
By segmenting the fairlead into fixed and removable portions, the design allows the fixed insert to provide stable mounting at specific points while the removable platelet absorbs and distributes the mechanical stresses, preventing stress concentration that would lead to cracks in the boot structure.
Solution Approach 2:
The removable platelet acts as a protective element that cushions and distributes mechanical stresses before they can concentrate on the boot plastic or structural components. This preemptive stress distribution prevents crack formation and extends boot durability.
4Device complexity
If the cable is completely exposed to possible shocks and frictions around the fairlead, then the fairlead structure is simple, but the cable may lead to weakening and breakage
Solution Approach 1:
Dividing the fairlead into fixed and removable segments allows the removable platelet to serve as a protective housing for the cable. This segmentation adds minimal complexity to the fixed portion while significantly improving cable protection against shocks and frictions.
Solution Approach 2:
The removable platelet serves as an intermediary protective structure between external shocks/frictions and the cable. It absorbs and distributes these external forces, preventing direct damage to the cable while adding only minimal structural complexity.
Data Source
Figure 1
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Figure 2b
AI summary
A ski boot or off-track ski boot (4) comprising a lower part or foot portion (8), suitable to embrace the foot of the user and an upper portion or leg portion (12), suitable to embrace the lower leg of the skier, the foot portion (8) and/or the leg portion (12) being provided with flaps (24,28) separate and facing each other, provided with fastening means (32) to allow the opening, closing and tightening of said flaps (24, 28). Advantageously, at least one of said fastening means (32) is attached to a flap (24, 28) by means of a cable (56), said cable (56) being at least partially inserted in a seat (60) delimited by a fairlead (64), wherein the fairlead (64) comprises an insert (68) attached to the flap (24, 28) and a removable platelet (72), joined and superposed to a portion of the insert (68).