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The University of Southampton

Research project: Passive vibration isolation using nonlinear characteristics

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Passive vibration control by isolation uncouples a source from a receiving structure. The effect is dependent on the frequency of the source excitation, whether it is a transient input such as a shock, the dynamic characteristics of the source and receiver and also whether there is any damping in the isolation.

Shock isolation using switchable stiffness
The shock response can be reduced if the isolation produces a low natural frequency of the equipment moving on the isolation, but this is unacceptable for supporting the static load of the equipment. So this project switches the stiffness by electromagnets during the input time.

Shock isolation using friction
Friction is introduced onto the isolated mass, or an attached mass-spring system, to reduce the response during the shock input and the residual vibration after the shock. Control strategies for when to apply the friction to get the maximum benefit are established.

Isolation systems with nonlinear (cubic) damping
A detrimental effect of linear viscous damping is the isolation response at frequencies above the isolation frequency. This project has considered the potential of nonlinear damping (i.e. proportional to velocity cubed), as measured in automotive shock absorbers, for the case of base and force excitation.

state isolation for mass M
High and low stiffness
results with (red) and without (blue) switching for a shock input
Comparison of experimental
model representation
Two degree of freedom
measured responses for a shock with switchable friction
Comparison of predicted and
and cubic damping contributions
Isolation system with linear
a shaker to reproduce the nonlinear damping
Experimental validation using

Related research groups

Dynamics Group
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