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A shock wave barrier comprises a periodic structure having the proper symmetry and local contrast modulation of the acoustic index to divert an incident shock wave by using constructive/destructive interference phenomena that produce a “band gap” in the transmission spectrum of the periodic structur

A shock wave barrier comprises a periodic structure having the proper symmetry and local contrast modulation of the acoustic index to divert an incident shock wave by using constructive/destructive interference phenomena that produce a “band gap” in the transmission spectrum of the periodic structure. In general, shock wave energy within the band gap is reflected from the structure. Defect cavities may be formed in the periodic structure to create transmission resonances or “windows” in the band gap. A portion of the incident energy passes through the window and is concentrated in the defect cavities where it is dissipated by other means. The band gap can be quite wide, at least 50% of the center wavelength, and thus can provide an effective barrier from a wide variety of threats with varying blast pressure and range. The structure may be periodic in two or three dimensions providing a band gap barrier in two or three dimensions, respectively.

대표청구항 ▼

1. A shock wave barrier for an asset in a protected area, comprising: first and second media arranged in a multidimensional periodic structure having a symmetry, said structure positioned between the protected area and one or more potential explosive detonation threats, said first and second media h

1. A shock wave barrier for an asset in a protected area, comprising: first and second media arranged in a multidimensional periodic structure having a symmetry, said structure positioned between the protected area and one or more potential explosive detonation threats, said first and second media having different acoustic indices of refraction that provide a local contrast modulation of the acoustic index that in conjunction with the symmetry of the structure defines a band gap in a transmission spectrum of the periodic structure, said first and second media spaced in the periodic structure to position the band gap coincident with the dominant wavelength of the shock wave for one or more potential explosive detonation threats. 2. The shock wave barrier of claim 1, wherein the periodic structure reflects show shock wave energy at wavelengths within the band gap. 3. The shock wave barrier of claim 1, wherein the periodic structure exhibits translational or rotational symmetry. 4. The shock wave barrier of claim 1, wherein the local contrast modulation of the acoustic index is at least 2:1. 5. The shock wave barrier of claim 1, wherein the periodic structure comprises at least six layers within which the shock wave constructively and destructively interferes to form the band gap. 6. The shock wave barrier of claim 1, wherein the first media comprises air. 7. The shock wave barrier of claim 6, wherein the local contrast modulation of the acoustic index is at least 10:1 and the width of the band gap is at least 50% of the center wavelength of the band gap. 8. The shock wave barrier of claim 1, wherein said first media comprises linear elements that provide local contrast modulation in two dimensions, said linear elements arranged in said second media in a three-dimensional periodic structure that define the local contrast modulation and band gap approximately in two dimensions. 9. The shock wave barrier of claim 8, wherein the linear elements may be retracted to permit ingress and egress from the protected area. 10. The shock wave barrier of claim 1, wherein said first media comprises three-dimensional geometric objects that provide local contrast modulation in three dimensions, said three-dimensional objects arranged in said second media in a three-dimensional periodic structure that defines the local contrast modulation and band gap in three dimensions. 11. The shock wave barrier of claim 1, further comprising: one or more defect cavities in the periodic structure that create a transmission resonance with the band gap that allows energy from the shock wave to pass into the structure where it is concentrated within the one or more defect cavities. 12. The shock wave barrier of claim 11, wherein the one or more defect cavities are filled with a third media that is ejected from the cavity to dissipate the energy. 13. The shock wave barrier of claim 11, wherein a plurality of said defect cavities forms a waveguide that routes the energy away from the protected area. 14. A shock wave barrier for an asset in a protected area, comprising: linear elements arranged in air around a protected area in a three-dimensional periodic structure that exhibits translational or rotational symmetry, said linear elements having an acoustic index of refraction of at most one-tenth that of air to provide a local contrast modulation of the acoustic index in two-dimensions of at least 10:1 that in conjunction with the symmetry of the structure defines a band gap in a transmission spectrum of the periodic structure, said linear elements spaced in the periodic structure to position the band gap coincident with the dominant wavelength of the shock wave for one or more potential explosive detonation threats, said band gap having a width of at least 50% of its center wavelength. 15. The shock wave barrier of claim 14, wherein the periodic structure reflects shock wave energy at wavelengths within the band gap. 16. The shock wave barrier of claim 14, further comprising: one or more defect cavities in the periodic structure that create a transmission resonance within the band gap that allows energy from the shock wave to pass into the structure where it is concentrated within the one or more defect cavities; andmeans for dissipating the energy in the one or more defect cavities. 17. The shock wave barrier of claim 14, wherein the linear elements may be retracted to permit ingress and egress from the protected area. 18. A shock wave barrier for an asset in a protected area, comprising: first and second media arranged in a multidimensional periodic structure having a symmetry, said structure positioned between the protected area and one or more potential explosive detonation threats, said first and second media having different acoustic indices of refraction that provide a local contrast modulation of the acoustic index that in conjunction with the symmetry of the structure defines a band gap in a transmission spectrum of the periodic structure, said first and second media spaced in the periodic structure to position the band gap coincident with the dominant wavelength of the shock wave for one or more potential explosive detonation threats;one or more defect cavities in the periodic structure that create a transmission resonance with the band gap that allows energy from the shock wave to pass into the structure where the energy is concentrated within the one or more defect cavities; andmeans for dissipating the energy in the one or more defect cavities. 19. The shock wave barrier of claim 18, wherein the means for dissipating the energy comprises a third media in the one or more defect cavities that is ejected from the cavity to dissipate the energy. 20. The shock wave barrier of claim 18, wherein the means for dissipating the energy comprises a waveguide formed by a plurality of said defect cavities that routes the energy away from the protected area.