Road Sign Support with Inward Bends for Impact Energy Absorption
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Solution Overview
Problem
Conventional roadside support structures are inadequate in absorbing impact energy during vehicle collisions, leading to potential harm to occupants and pedestrians, and suffer from fatigue cracks due to repetitive loading, especially under wind conditions.
Innovation Solution
The support structure features a deformable design with inwardly-directed bends and port sections that promote energy absorption, along with an anchoring system that reduces stress concentrations and fatigue, including a sleeve member with a tapered bore and cut-outs to facilitate anchoring fastener shearing during impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional tubular support structures are used, then the structure is low cost and easy to construct, but the structure absorbs minimal impact energy and poses high risk to occupants and pedestrians
Solution Approach 1:
The support member transitions from a rigid static structure to a dynamic deformable structure. The inwardly-directed bends are designed to deform during impact, allowing the structure to absorb energy through controlled deformation rather than remaining rigid and transmitting full impact force to occupants.
Solution Approach 2:
The geometric parameters of the support member are changed by introducing inwardly-directed bends at specific locations. These bends create predetermined deformation zones that change the structural characteristics, enabling energy absorption through progressive collapse mechanisms during impact events.
2Strength
If rigid support structures are used, then the structure maintains high stiffness and strength, but the structure generates high forces on vehicles and occupants during impact
Solution Approach 1:
The inwardly-directed bends convert the harmful rigid structure into a beneficial energy-absorbing structure. The bends are designed to deform in a controlled manner during impact, transforming the harmful impact energy into useful deformation work within the structure itself, thereby reducing the force transmitted to occupants.
3Ease of manufacture
If smooth cylindrical support members are used, then the structure has simple geometry and manufacturing, but the structure experiences high vibration and fatigue from vortex shedding
Solution Approach 1:
The support member transitions from a symmetric smooth cylinder to an asymmetric cross-section with inwardly-directed bends. This asymmetry disrupts the symmetric vortex shedding pattern that occurs around smooth cylinders, reducing vibrational forces and fatigue accumulation in the structure.
4Strength
If the support member is designed for high energy absorption, then the structure reduces exit speed of impacting vehicles, but the structure requires complex geometry and manufacturing
Solution Approach 1:
The support member is segmented into distinct regions: port sections for anchoring and wall sections containing inwardly-directed bends for energy absorption. This segmentation allows each region to be optimized for its specific function while maintaining overall structural integrity and manufacturability through extrusion 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 deformable design enhances energy absorption, reduces the risk of harm during collisions, and minimizes fatigue by disrupting vortex-shedding and distributing impact forces, while the anchoring system ensures controlled failure and reduced stress concentrations, thereby improving safety and longevity.
Implementation Method 1
the inwardly-directed bend of the wall sections promotes inward collapsing of the support member in the event of an impact thereby reducing the stiffness of the support member, which in turn will reduce the forces on the vehicle and occupants. Also, because the form of the wall sections promotes local collapse of the support member, as opposed to fracture, the likelihood is of a higher level of energy absorption
Implementation Method 2
the cross-section of the support member has a shape that includes external features that will disrupt vortex-shedding thus reducing vibration of the structure and the tendency for fatigue
Implementation Method 3
an anchoring system anchoring the support structure to a base, said anchoring system comprising: a sleeve member engageably received in the port section, the sleeve member having an extended inward end portion sized to provide a close fit inside the port section and a tapered bore
Implementation Method 4
a cut-out formed in the tubular support member between adjacent ports, the cut-out extending longitudinally from the end. Preferably, the cut-out extends for a width between adjacent ports and for a longitudinal distance from the end, said width and longitudinal distance being determined to provide a frictional resistance in the event of a predetermined impact force on said structure, which frictional resistance is insufficient to prevent shearing of at least one of said anchoring fasteners
Data Source
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AI summary
The invention relates to a support structure for use in supporting a road sign or the like. A longitudinal tubular support member has a uniform cross-section that includes a plurality of circular or part-circular port sections for receiving an end anchorage. Enclosing wall sections extend between the port sections and are shaped to include a concave form so as to promote inward collapsing of the support member in the event of an impact to the support structure.