Analysis of Vibration-Damping Mechanism in Shock-Absorbing Casters (For Design Selection and Failure Analysis Reference)

Time：Sep 19,2025

1. Elastomeric Energy Absorption

The wheel surface features either high-hysteresis-loss rubber or cast polyurethane, which converts mechanical energy into heat through molecular chain segment relaxation. The hardness is adjustable (Shore A 65–95) and provides nonlinear stiffness within a compression strain range of 10–40%, enabling a "soft landing."

2. Spring Energy Storage

Metal coil springs or Belleville washers are placed between the wheel frame and the wheel axle, graded according to the stroke-load curve:

- Light-load section: Stiffness 0.8–1.2 N/mm, isolating ground vibrations in the 8–15 Hz range;

- Overload section: Stiffness 3–5 N/mm, limiting excessive displacement beyond 3 mm.

Multi-stage parallel configuration can cover impact spectra from 0.1 g to 5 g.

3. Damping Dissipation

3.1 Material Damping: Rubber with a loss factor tan δ ≥ 0.15 can convert more than 30% of vibrational energy into heat at 20°C and 50 Hz.

3.2 Hydraulic Damping: Cylinder bore 15–25 mm, using 32 cSt silicone oil, providing viscous damping with a velocity index of 0.3–0.5. The critical damping ratio ζ reaches 0.25, effectively suppressing resonance peaks in the 30–200 Hz range.

4. Structural Vibration Isolation

4.1 Independent Suspension: Swing arm + pivot structure decouples the degrees of freedom for each wheel, ensuring a ground unevenness transmissibility of ≤ 0.4 (ISO 2631 weighted).

4.2 Multi-Wheel Uniform Loading: With a 4-point or 6-point layout, the statically indeterminate structure reduces the dynamic load factor per wheel to 1/√n (where n = number of wheels), while also minimizing the overturning moment.

5. Hardness Gradient and Multilayer Composites

Adopting a "soft-hard-soft" sandwich structure:

- Tread ShA 75, offering high friction and initial cushioning;

- Middle ShA 95, controlling excessive deformation;

- Wheel hub ShD 65, ensuring rotational accuracy.

Finite element results show that, under a 500 N radial load, the gradient design reduces the peak acceleration for vibration damping by 18% compared to the homogeneous structure.

6. Fluid Elastic Element

6.1 Pneumatic Tire: Preload of 0.25–0.35 MPa; the equivalent stiffness exhibits a nonlinear relationship between air pressure and volume, resulting in an acceleration attenuation rate of 55–70% on uneven road surfaces with undulations ranging from 5 to 20 mm.

6.2 Liquid Filling: A 50% ethylene glycol solution with a bulk modulus of elasticity of 2.2 GPa, generating a damping backpressure of 0.15 MPa through a throttling orifice, suitable for precision instruments weighing 10–50 kg, and providing secondary impact amplitude attenuation exceeding 25 dB.

Conclusion

The vibration-damping casters utilize a four-stage series-parallel model—comprising "elastic deformation, spring energy storage, damping dissipation, and structural decoupling"—to reduce broadband random vibrations by 60–90%, thereby extending equipment lifespan by 2–4 times while meeting the ISO 2372 Class A vibration limits. When selecting the right caster, simply match the stiffness and damping characteristics to the load-speed-ground spectrum to ensure reliable vibration isolation.

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