Radially Flexible Bushing Arch Stop Stiffness
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Solution Overview
Problem
Existing radial bushings for linking and damping between rigid elements, such as transmission boxes and chassis, face limitations in operating life and performance, with high material usage and potential for localized stress zones leading to reduced fatigue life.
Innovation Solution
The radial bushing design incorporates an arch-shaped radial stop on the outer element with a tubular cavity filled with elastomer, providing multiple radial and axial stiffness options, and a bi-injection molding process to reduce material usage and inherent stresses, allowing for independent tuning of stiffness in various directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional radial bushing design is used, then structural simplicity is maintained, but operating life and performance are reduced due to localized stress zones
Solution Approach 1:
The radial stop is segmented into multiple arches spaced around the circumference, with each arch providing independent stress distribution. This segmentation prevents localized stress concentration while maintaining the overall structural integrity of the bushing.
Solution Approach 2:
The arch-shaped radial stop introduces a new geometric dimension (curved arch structure) compared to traditional flat stops. This dimensional change allows stress to be distributed along the arch curve, reducing localized stress zones and improving fatigue life.
2Strength
If more material is used to strengthen the bushing, then strength is improved, but manufacturing cost increases
Solution Approach 1:
The arch-shaped radial stop concentrates material only where stress occurs (at the radial stop location), rather than uniformly throughout the bushing. This localized material placement provides necessary strength while minimizing overall material usage and manufacturing cost.
Solution Approach 2:
The bushing combines different materials (metal outer element with elastomer arms) to achieve optimal strength-to-weight ratio. The elastomer provides damping and flexibility while the metal arch provides structural strength, creating a composite structure that is both strong and material-efficient.
3Stress or pressure
If radial stop is added to limit displacement, then radial stiffness is improved, but stress concentration increases reducing fatigue life
Solution Approach 1:
The radial stop is designed with a curved arch shape instead of a straight or flat geometry. This curvature allows stress to be distributed along the arch's length, preventing stress concentration at sharp corners or edges, thereby maintaining radial stiffness while improving fatigue life.
Solution Approach 2:
The arch is pre-formed during manufacturing with the correct geometry and material properties, so that when the bushing is assembled and operated, the stress distribution is optimized from the beginning. This preliminary structuring prevents stress concentration before it can cause fatigue damage.
4Adaptability or versatility
If multiple radial stops with different stiffness are provided, then adaptability is improved, but device complexity increases
Solution Approach 1:
Different arches around the circumference can have different geometries (different heights, thicknesses, or curvatures), allowing each location to have customized stiffness properties. This local differentiation provides adaptability for multi-directional stiffness tuning without requiring completely separate components.
Solution Approach 2:
The arch-shaped radial stop design serves multiple functions: it provides radial displacement limitation, acts as a stress-distributing structure, and can be customized for different stiffness requirements. This multi-functionality reduces the need for separate specialized components.
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 operating life and performance of radial bushings by reducing material usage, minimizing stress zones, and enabling longer fatigue life through pre-compression and independent stiffness tuning in multiple axes.
Implementation Method 1
an elastomer body, which adherently attaches the outer periphery of said inner rigid element and said outer element
Implementation Method 2
said elastomer body comprising a plurality of spaced-apart arms extending radially from said inner rigid element to said outer element
Implementation Method 3
said radial stop is positioned on said outer element between said arms, and comprises an arch having extremities joined to said outer element and a top oriented towards said rigid element, said arch defining with said outer element a tubular cavity
Implementation Method 4
a bi-injection molding process to reduce material usage and inherent stresses, allowing for independent tuning of stiffness in various directions
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
This invention provides for a radially flexible bushing, comprising an outer annular element (1), an inner rigid element (2) surrounded by the outer element, an elastomer body (3), which adherently attaches the inner rigid element and the outer element. The elastomer body comprises spaced-apart arms (4) extending radially from the inner rigid element to the outer element. It further comprises at least one radial stop (5) for limiting the radial displacement of the inner rigid element. The radial stop, which is positioned on the outer element between the arms, comprises an arch (6) having extremities joined to the outer element and a top oriented towards the rigid element. The arch defines together with the outer element a tubular cavity (7).