Compliant Shear Element for Elevator Suspension Termination
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Solution Overview
Problem
Elevator systems with suspension members made from unidirectional fibers in a rigid matrix face issues with traditional termination methods, as these fibers fracture when bent around a wedge and require high clamping forces, leading to shear stress and potential damage.
Innovation Solution
A termination device with a housing and wedge assembly that includes a compliant shear element to reduce shear loads, secured via adhesives, mechanical fasteners, or interlocking features, and featuring friction-enhancing elements to manage the tension members effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional wedge-based termination is used for suspension members with unidirectional fiber tension members, then the suspension member can be terminated, but the fibers fracture when bent around the wedge
Solution Approach 1:
A compliant shear element is introduced as an intermediary component between the wedge and the suspension member. This shear element has a lower modulus of elasticity than the tension members, allowing it to deform and accommodate the unidirectional fibers during termination without causing fracture, while still transmitting the necessary clamping force.
Solution Approach 2:
The patent changes the mechanical parameter (modulus of elasticity) of the interface between the wedge and suspension member by introducing a compliant shear element. This element provides a softer, more compliant interface that reduces bending stresses on the rigid unidirectional fiber tension members during the termination process.
2Reliability
If high clamping forces are applied to retain the suspension member, then the suspension member is securely retained, but high shear stresses damage the belt at the jacket/tension member interface
Solution Approach 1:
The compliant shear element acts as a mediator that decouples the high clamping force from the suspension member. It absorbs the shear stress through its own deformation, protecting the jacket/tension member interface from damage while still allowing the wedge to apply sufficient clamping force for secure retention.
Solution Approach 2:
The patent introduces a component with specifically tailored mechanical properties (lower modulus of elasticity) that changes the stress distribution pattern. The compliant shear element undergoes shear deformation, converting part of the clamping force into shear strain in itself rather than transmitting full shear stress to the suspension member interface.
3Strength
If unidirectional fiber tension members are used, then the suspension member has high strength, but the fibers cannot be spread and bent for traditional potted arrangements
Solution Approach 1:
The compliant shear element serves as an intermediary that enables termination of unidirectional fiber tension members without requiring them to be spread or bent. It provides a compliant interface that accommodates the rigid fiber structure, allowing these high-strength materials to be terminated using modified wedge-based arrangements.
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 compliant shear element reduces shear stress and prevents damage at the tension member-jacket interface, ensuring secure termination without slippage and maintaining the integrity of the suspension member.
Implementation Method 1
a compliant shear element secured to the wedge or the suspension member and configured to reduce shear loads on the suspension member
Implementation Method 2
a wedge assembly located in the housing. The wedge assembly includes a wedge interactive with the housing to apply a clamping force to the suspension member
Data Source
AI summary
A termination device for a suspension member of an elevator system includes a housing and a wedge assembly located in the housing. The wedge assembly includes a wedge interactive with the housing to apply a clamping force to the suspension member in response to an axial load acting on the suspension member and a compliant shear element secured to the wedge or the suspension member and configured to reduce shear loads on the suspension member.