Self diagnostic composite armor

• US 8,752,432 B2
• Filed: 06/30/2011
• Issued: 06/17/2014
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: U.S. Government
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Meitzler, Thomas J., Wong, Ivan, Reynolds, Thomas P., Ebenstein, Samuel E.
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): WEST, PAUL M
• Application Number:
  US13/173,766
• Publication Number:
  US 20130000408A1
• Time in Patent Office: 1,083 Days
• US Class Current: 73/588
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/2475 Embedded probes, i.e. probes incorporated in objects to be inspected

Abstract

A system incorporating sensor enhanced composite armor structure. The structure has one layer including ceramic tiles and ceramic-material transducers, wherein the ceramic tiles and the transducers fit closely together so that the one layer is ballistically windowless. The structure has other layers composed of armor material stacked with the one layer, the one layer and the other layers forming a plate which as a unit has a set or group of fundamental frequencies. The system includes logic means to analyze only signals resulting from vibrations transmitted from the one transducer to the other transducer through the one layer. The logic means thereby derives a signal fingerprint which characterizes a state of damage to the plate.

Claims

1. A system including a self diagnostic composite armor structure, comprising:

ceramic tiles in one layer of the armor structure, the tiles having a regular polygonal outline;

transducers in the one layer, one of the transducers sending vibrations detected by another of the transducers, the transducers being of ceramic material and having a same thickness and a same regular polygonal outline as the regular polygonal outline of the ceramic tiles;

wherein the other of the transducers responds essentially only to vibrations travelling parallel to the one layer;

wherein the ceramic tiles and the transducers fit closely together so that the one layer is a ballistically windowless layer;

a bonding agent between adjacent ceramic tiles and between adjoining ceramic tiles and transducers, the agent enhancing the passage of vibrations from the one transducer to the other transducer through the ceramic tiles;

other layers of armor material stacked with the one layer so that the one layer and the other layers form a plate which vibrates as a unit and has characteristic fundamental frequencies;

logic means to analyze signals resulting from vibrations transmitted from the one transducer to the other transducer parallel to the plate through the one layer to derive a signal fingerprint characterizing an undamaged plate, the logic means capable of using the vibrations to determine an initial change in the fingerprint and to thus detect initial damage to the plate, and determine the health of the entire plate;

wherein the logic means can continue to analyze vibrations after the initial change in the fingerprint to determine a subsequent change in the received vibrations and detect subsequent additional damage to the plate; and

transducer damage detection means to detect cessation of transducer function, thereby detecting damage to the plate in the form of damage to one or more of the transducers.

2. The self diagnostic armor system of claim 1 wherein:

a plurality of the plates are disposed on a vehicle;

the plates vary in size and shape;

the other layers in a first plate have different materials and layer thicknesses than a second plate;

a computer on board the vehicle contains a record of the signal fingerprint and location of each plate on the vehicle.

3. A self diagnostic composite armor system, comprising:

ceramic tiles of uniform shape pressed together in one layer of the armor structure, the tiles having a regular polygonal outline;

piezoelectric transducers in the one layer at opposed edges of the one layer, one of the transducers sending vibrations detected by another of the transducers, the transducers being of ballistically protective ceramic material and having a same thickness and a same regular polygonal outline as the regular polygonal outline of the ceramic tiles;

wherein the ceramic tiles and the transducers fit closely together so that the one layer is a continuous, unapertured, ballistically windowless layer;

a bonding agent between adjacent ceramic tiles and between adjoining ceramic tiles and transducers, the agent enhancing the passage of vibrations from the one transducer to the other transducer through the ceramic tiles;

other layers of armor material stacked with the one layer so that the one layer and the other layers form a plate which vibrates as a unit and has characteristic fundamental frequencies;

logic means to analyze signals resulting from vibrations transmitted from the one transducer to the other transducer travelling parallel to the plate through the one layer to derive a signal fingerprint characterizing an undamaged plate, the logic means capable of using the vibrations to determine an initial change in the signal fingerprint and to thus detect initial damage to the plate;

wherein the logic means can continue to analyze the vibrations after the initial change in the fingerprint to determine a subsequent change in the fingerprint and detect subsequent additional damage to the plate; and

transducer damage detection means to detect cessation of transducer function, thereby detecting damage to the plate in the form of damage to one or more of the transducers.

4. The self diagnostic composite armor system of claim 3 wherein the transducers are selected so as to be sensitive to the fundamental frequencies of the composite armor system by using an impedance analyzer to determine the frequency range of the transducers.