Blast/impact frequency tuning and mitigation

Patent metadata

Field	Value
Publication number	US-2016298936-A1
Application number	US-201415036293-A
Country	US
Kind code	A1
Filing date	Nov 14, 2014
Priority date	Nov 14, 2013
Publication date	Oct 13, 2016
Grant date	—

Abstract

A protective device and method of design to protect against multiple blast and impact events for use in any application in which a delicate target has to be protected. The protective device for mitigating the effects of blast or impact employs a first layer having a first acoustic impedance and a second layer having a second acoustic impedance. The second acoustic impedance is different than the first acoustic impedance. The second layer is proximate to the first layer. The first layer and the second layer are chosen collectively to tune the stress waves from the blast or impact events to one or more specific tuned frequencies. A third layer of a visco-elastic material is employed having a critical damping frequency that matches one or more specific tuned frequencies to dissipate the stress waves of the blast and impact event. The third layer is proximate to the second layer.

First claim

1 .- 11 . (canceled)

12 . A protective device for mitigating a blast or impact frequency, said protective device comprising:
a first layer having a first acoustic impedance; a second layer having a second acoustic impedance, said second acoustic impedance being different than said first acoustic impedance, said second layer being proximate to said first layer, said first layer and said second layer are chosen collectively to tune stress waves resulting from the blast or impact to one or more specific tuned frequencies; and a third layer being made of a visco-elastic material having a critical damping frequency that matches at least one of said one or more specific tuned frequencies, said third layer being proximate to said second layer.

13 . The protective device according to claim 12 wherein said first layer and said second layer are chosen collectively to tune stress waves resulting from the blast or impact to said one or more specific tuned frequencies using geometrical parameters.

14 . The protective device according to claim 12 wherein said first layer and said second layer are chosen collectively to tune stress waves resulting from the blast or impact to said one or more specific tuned frequencies using material parameters.

15 . The protective device according to claim 12 wherein said first layer and said second layer are chosen collectively to allow passage of said one or more specific tuned frequencies to said third layer, whereby said one or more specific tuned frequencies is dissipated in said third layer.

16 . The protective device according to claim 12 wherein said first layer and said second layer are chosen collectively to allow passage of said one or more specific tuned frequencies to said third layer, whereby said one or more specific tuned frequencies is visco-elastically dissipated in said third layer.

17 . The protective device according to claim 12 wherein said third layer is made of a material sufficient to visco-elastically dissipate a plurality of cycles of the one or more specific tuned frequencies.

18 . The protective device according to claim 12 wherein said third layer is made of a material sufficient to visco-elastically recover within the time scale of the cyclic loading of the one or more specific tuned frequencies.

19 . The protective device according to claim 12 wherein a thickness of said third layer is sufficient that the presence of a stress wave of said one or more specific tuned frequencies substantially decay before passage of said stress wave through said third layer.

20 . The protective device according to claim 12 wherein said second layer is joined to said first layer.

21 . The protective device according to claim 12 wherein said third layer is joined to said second layer.

22 . The protective device according to claim 12 wherein said first layer and said second layer are chosen collectively to increase a time scale of the stress waves resulting from the blast or impact.

23 . The protective device according to claim 12 wherein said first layer is made of an elastic material.

24 . The protective device according to claim 12 wherein said second layer is made of an elastic material.

25 . The protective device according to claim 12 wherein said second acoustic impedance is less than said first acoustic impedance.

Assignees

• Univ Michigan Regents

Inventors

• Thouless Michael
• Arruda Ellen M
• Rahimzadeh Tanaz
• Waas Anthony M

Classifications

• B32B15/08

  of synthetic resin · CPC title

• F42D5/045

  Detonation-wave absorbing or damping means · CPC title

• F41H5/04 Primary

  composed of more than one layer {(outerwear resistant to mechanical aggressions A41D31/24; layered products B32B; shaping reinforced articles B29C67/00)} · CPC title

• B32B2250/03

  3 layers · CPC title

• F41H1/04

  Protection helmets (crash helmets A42B3/00) · CPC title