Monolithic Energy Absorber Shear Pin Trigger for Torque Reduction
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Solution Overview
Problem
Existing shock absorbing devices for fall protection systems face challenges in effectively reducing torque and moment forces on structures during falls, leading to potential damage and increased risk of injury, as they often require complex designs to manage high forces efficiently.
Innovation Solution
The development of an energy absorber made from ductile material with a monolithic length, featuring a first longitudinally extending section deformed out of plane and connected by shear pins, which disconnects under a threshold tensile force, allowing the section to deform and absorb energy, thereby reducing forces on structures and users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If complex shock absorbing devices are used to reduce forces on structures during falls, then force reduction capability is improved, but device complexity increases
Solution Approach 1:
The energy absorber is segmented into multiple functional zones within a single component: a deformable energy-absorbing section with alternating thick and thin walls, connected sections for attachment, and a trigger mechanism with shear pins. This segmentation allows different portions to perform different functions (energy absorption, connection, trigger activation) while maintaining overall system simplicity
Solution Approach 2:
The trigger mechanism is extracted as a separate functional element that can be independently designed and activated. The shear pins are removable components that can be replaced after activation, separating the trigger function from the permanent energy-absorbing structure
Solution Approach 3:
The energy absorber transitions from a static rigid structure to a dynamic system that changes configuration during operation. The deformable section with varying wall thicknesses is designed to collapse progressively under load, with the thin-walled portions deforming first to absorb energy while the thick-walled portions remain intact until higher loads are applied
2Force
If posts are designed to tilt or tip over to reduce torque on roof structures, then torque reduction is improved, but structural stability deteriorates
Solution Approach 1:
The energy absorber is pre-configured with a trigger mechanism (shear pins) that activates at a predetermined force threshold. This preliminary design ensures that the post will tilt at the correct moment during a fall event, preventing excessive torque from being transmitted to the roof structure while maintaining stability during normal use
Solution Approach 2:
The system changes its mechanical parameters dynamically: during normal conditions, the shear pins maintain the post in a stable vertical position; during a fall event, when force exceeds the threshold, the shear pins shear off, changing the post's degree of freedom from fixed to movable, allowing it to tilt and absorb energy
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
This solution effectively reduces torque and moment forces on structures during falls, minimizing damage and injury by dissipating energy through controlled deformation of the energy absorber, ensuring secure attachment and operation only under extreme conditions.
Implementation Method 1
the first longitudinally extending section is free to deform under tensile force (and extend in longitudinal direction) to absorb energy
Implementation Method 2
The first discontinuous section and the second discontinuous section are connected such that tensile force of a threshold magnitude is required between the first end and the second end to disconnect the first discontinuous section from the second discontinuous section
Data Source
AI summary
An energy absorber includes a monolithic length of ductile material comprising a first end and a second end. The material is formed to include at least a first longitudinally extending section that extends continuously between the ends, a first discontinuous section extending longitudinally from the first end toward the second end and at least a second discontinuous section extending longitudinally from the second end toward the first end. The first longitudinally extending section is deformed over at least a portion thereof out of a plane running through both ends. The first discontinuous section and the second discontinuous section are connected such that tensile force of a threshold magnitude is required between the ends to disconnect the first discontinuous section from the second discontinuous section, letting the first longitudinally extending section free to deform under tensile force and extend in longitudinal direction.