Composite Shock Absorber Base with Axial Flexibility Compensation
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Solution Overview
Problem
Conventional shock absorbers using steel outer tubes are heavy and prone to damage due to reduced strength when wall thickness is minimized for weight reduction, and composite materials, while lighter, exhibit greater elongation and misalignment issues under axial loading, leading to increased noise and decreased performance.
Innovation Solution
A shock absorber design incorporating a composite base assembly with a lower element that engages the pressure tube to restrict lateral movement and allow longitudinal movement, compensating for axial flexibility differences and maintaining alignment between the inner assembly and composite base, using a thermosetting fiber-filled polymer with a lower elastic modulus than steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the wall thickness of the outer tube is reduced to decrease weight, then the weight of the shock absorber is reduced, but the strength and resistance to damage are reduced
Solution Approach 1:
The outer tube is constructed from composite materials (such as carbon fiber reinforced polymers) instead of traditional steel, enabling significant weight reduction while maintaining or improving strength and stiffness characteristics. The composite structure provides high strength-to-weight ratio, resolving the contradiction between weight reduction and strength maintenance.
2Weight of moving object
If composite materials are used to reduce weight, then the weight is reduced, but the material exhibits greater elongation and misalignment under axial loading
Solution Approach 1:
The elastic modulus of the composite material is specifically engineered to be lower than steel (typically in the range of 2-10 GPa versus 200 GPa for steel), which allows controlled flexibility while maintaining alignment through the lower element's mechanical constraints. This parameter change enables the composite to absorb axial loads without excessive elongation that would cause misalignment.
Solution Approach 2:
The lower element acts as an intermediary component between the composite outer tube and the internal components. It provides mechanical support and alignment constraints, compensating for the composite material's inherent flexibility. The lower element ensures that internal components remain properly aligned even when the composite tube undergoes axial deformation.
3Stability of the object's composition
If a lower element with gaps is introduced to maintain alignment, then the alignment stability is improved, but the device complexity increases
Solution Approach 1:
The lower element is designed to perform multiple functions simultaneously: it provides alignment constraints for the pressure tube, maintains the pre-load condition between composite tubes, allows fluid communication through integrated gaps, and supports axial movement. By combining these functions into a single component, the design minimizes additional complexity while achieving alignment stability.
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 solution effectively dampens axial movement, maintains alignment, and reduces weight while improving reliability and performance by utilizing lightweight composite materials, ensuring consistent operation even under varying loads and temperatures.
Implementation Method 1
composite materials have a lower stiffness and therefore have greater elongation than metals... axial rebound loading of the shock absorber may cause a composite outer tube to deform significantly
Data Source
AI summary
A shock absorber including an inner assembly and a composite base assembly is disclosed. The inner assembly includes a pressure tube extending between first and second ends, a rod guide disposed adjacent to the first end, a compression valve disposed adjacent to the second end, a piston assembly disposed in the pressure tube between the rod guide and the compression valve, and a rod operatively attached to the piston assembly and supported by the rod guide. The composite base assembly defines a chamber for at least partially accommodating the inner assembly that terminates at a floor. The composite base assembly has a lower element disposed adjacent to the floor for at least partially engaging the second end of the pressure tube. The lower element defines at least one gap for facilitating fluid communication between the pressure tube and the chamber.