Available Technology

Active Controlled Energy Absorber Using Responsive Fluids

Traditional active energy absorbent materials are able to change their material properties in order to tailor their energy absorbing characteristic to different impact loads. However, these materials have to be optimized, a priori, to work over a range of impact energies, and are normally characterized by an ‘off state’- compliant and comfortable; and ‘on state’-stiff and energy absorbent. The mechanism of activation is normally the impact, rather than external activation and requires large deformations. These materials are very efficient, but rely on passive activation and cannot be “actively tuned” through external user control to best match a given operational setting. This technology proposes an adaptive active mechanism for energy absorption that uses dilatant fluids which can be rapidly and reversibly actuated by imposing small amplitude high frequency oscillations.
The dilatant fluid is a highly concentrated suspension dispersed and stabilized in a carrier fluid that behaves like a low conventional viscosity fluid when low shear rates are applied but increases its viscosity and ultimately solidifies at high shear rates. There are two ways to achieve shear-induced thickening of these dilatant fluids: first, the method most commonly known and exploited in the past, is achieved by applying a large deformation or strain at a high enough rate; a second way is by inducing a localized rapidly varying shear field. One possible way to achieve this is by applying small amplitude high frequency oscillation. The construction of the material/mechanism is a layer of dilatant fluid sandwiched between two oscillating plates. The plates do not necessarily need to be rigid in their entirety, but can be an array of small oscillators that can bend relative to each other, as in a flexible frame. This arrangement allows a flexible and actively controlled energy absorber.
Active control of energy absorber mechanism - Design flexibility to fit different systems
Giorgia Bettin
Lab Representatives
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