Hollow Profile for Weight-in-Motion Sensor
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Solution Overview
Problem
Conventional WIM sensor hollow profiles are prone to permanent damage due to high stress peaks, especially at the transition areas from the tubular part to the force application plates, leading to reduced sensor sensitivity and shortened service life under dynamic loads from heavy vehicles.
Innovation Solution
The hollow profile design features thinner areas acting as flexure joints, which absorb stress peaks and distribute forces more evenly, combined with thicker areas for support, optimizing stress distribution and minimizing material reinforcement to maintain sensitivity while extending the profile's service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the wall thickness of the tubular part is increased to withstand high stresses from heavy vehicles, then the strength and durability of the profile is improved, but the sensitivity of the WIM sensor deteriorates due to force shunting
Solution Approach 1:
The tubular part is designed with non-uniform wall thickness, featuring thinner areas at specific locations and thicker areas at other locations. This local variation in thickness allows the structure to have different mechanical properties at different positions, enabling it to withstand high stresses while maintaining sensor sensitivity in critical measurement zones.
2Reliability
If the wall thickness is uniformly increased throughout the tubular part, then the profile can withstand operating loads better, but stress peaks are not reduced and service life is not extended
Solution Approach 1:
The non-uniform wall thickness distribution creates thinner areas that act as stress-relieving zones, reducing stress peaks during vehicle passage. This local thinning prevents material fatigue and cracking, thereby extending the service life of the profile while maintaining overall structural reliability through strategically placed thicker areas.
3Duration of action of stationary object
If the tubular part is reinforced to reduce stress peaks, then the service life is extended, but the force shunting effect increases and sensor sensitivity is reduced
Solution Approach 1:
The strategic placement of thinner areas in the tubular part creates controlled flexibility zones that reduce stress peaks without creating significant force shunting. These localized thin sections allow the tube to flex slightly under load, dissipating stress while maintaining sufficient stiffness to transmit measurement forces effectively to the sensors.
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 design enhances the profile's ability to withstand operating loads, reducing stress peaks and extending the service life of WIM sensors without compromising sensitivity, thus improving measurement accuracy and durability.
Implementation Method 1
thinner areas on the pipe segments act like solid joints, which allow bending in these areas more readily than, in particular, thicker areas
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to an oblong hollow profile (1) for a WIM (weight-in-motion) sensor, comprising two force-transmission plates (2) arranged parallel to each other and a tube (3) arranged between said plates (2), which is integrally formed with the plates (2) and forms a hollow space (5). Two supports (6) that are arranged opposite one another are formed inside the hollow space (5), each one extending away from a respective plate (2) and between which a measuring element (7) can be received centrally in the tube (3) under preload. The tube (3) comprises two tube segments (8) designed to be mirror-symmetrical with respect to each other, which join the plates (2) together and on the inside adjoin the hollow space (5). According to the invention the wall thickness (9) of each tube segment (8) has at least two relatively thin regions (10) and a relatively thick region (11) therebetween.