NASA Technical Reports Server (NTRS) 20160001294: Multi-Dimensional Damage Detection Multi-Dimensional Damage Detection

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by  NASA Technical Reports Server (NTRS)

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(12) United States Patent (lo) Patent No.: (cid:9) US 9,233,765 B2
Gibson et al. (45) Date of Patent: (cid:9) Jan. 12, 2016
(54) MULTI-DIMENSIONAL DAMAGE (56) References Cited
DETECTION
U.S. PATENT DOCUMENTS
(75) Inventors: Tracy L. Gibson, Melbourne, FL (US);
Martha K. Williams, Titusville, FL 6,370,964 B1 * 4/2002 Chang et al . (cid:9) ............. 73/862.046
6,768,312 132 7/2004 Sun et al.
(US); Mark E. Lewis, Merritt Island, FL
7,277,822 132 * 10/2007 Blemel (cid:9) ......................... 702/183
(US); Luke B. Roberson, Titusville, FL
7,413,919 132 8/2008 Qing et al.
(US); Sarah J. Snyder, Terre Haute, IN 7,676,775 132 * 3/2010 Chen et al ..................... 716/136
(US); Pedro J. Medelius, Merritt Island, 2004/0238686 Al 12/2004 Sneed
FL (US); Steven L. Parks, Rockledge, 2005/0284232 Al* 12/2005 Rice (cid:9) ................................ 73/762
FL (US)
(Continued)
(73) Assignee: The United States of America as
FOREIGN PATENT DOCUMENTS
Represented by the Administrator of
the National Aeronautics and Space JP (cid:9) 2009006497 A (cid:9) 1/2009
Administration, Washington, DC (US)
OTHER PUBLICATIONS
(*) Notice: (cid:9) Subject to any disclaimer, the term of this
patent is extended or adjusted under 35 M. Kokot, Damage Identification in Electrical Network for Structural
U.S.C. 154(b) by 668 days. Health Monitoring, Ph.D. Dissertation, 2011, pp. 1-102.
(Continued)
(21) Appl. No.: 13/495,862
(22) Filed: (cid:9) Jun. 13, 2012 Primary Examiner Justin Benedik
(74) Attorney, Agent, orFirm Michelle L. Ford; B. Delano
(65) (cid:9) Prior Publication Data Jordan
US 2012/0318925 Al (cid:9) Dec. 20, 2012
(57) ABSTRACT
Related U.S. Application Data
Methods and systems may provide for a structure having a
(60) Provisional application No. 61/497,631, filed on Jun.
plurality of interconnected panels, wherein each panel has a
16, 2011.
plurality of detection layers separated from one another by
(51) Int. Cl. one or more non-detection layers. The plurality of detection
B64G 1152 (cid:9) (2006.01) layers may form a grid of conductive traces. Additionally, a
B64G 1122 (cid:9) (2006.01) monitor may be coupled to each grid of conductive traces,
wherein the monitor is configured to detect damage to the
(52) U.S. Cl.
plurality of interconnected panels in response to an electrical
CPC ............ B64G 1152 (2013.01); B64G 20011224
property change with respect to one or more of the conductive
(2013.01)
traces. In one example, the structure is part of an inflatable
(58) Field of Classification Search
space platform such as a spacecraft or habitat.
CPC ............................ B64G 1/52; B64G 2001/224
USPC ....................................................... 244/158.3
See application file for complete search history. 9 Claims, 5 Drawing Sheets
-3t)
US 9,233,765 B2
Page 2
(56) References Cited 2012/0111599 Al * (cid:9) 5/2012 (cid:9) Roberson et al . (cid:9) ............. (cid:9) 174/107
2012/0188078 Al (cid:9) 7/2012 (cid:9) Soles et al.
U.S. PATENT DOCUMENTS
OTHER PUBLICATIONS
2006/0053534 Al 3/2006 Mullen
2006/0082366 Al 4/2006 Goldfine et al. E. Brandon, Damage Detection and Self-Repair in Inflatable/
2006/0283266 Al 12/2006 Qing et al.
Deployable Structures, NASA Tech Briefs, Mar. 2009, vol. 33, No. 3,
2007/0183110 Al* 8/2007 Woodard et al ............... 361/103
2008/0075934 Al* 3/2008 Barlow et al .................. 428/199 (cid:9) P. 19.
2010/0161244 Al 6/2010 Ghoshal et al.
2011/0107843 Al 5/2011 Hucker et al. * cited by examiner
U.S. Patent (cid:9) Jan. 12,2016 (cid:9) Sheet I of 5 (cid:9) US 9,233,765 B2
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MULTI-DIMENSIONAL DAMAGE FIG. 2 is a diagram of an example of a detection pattern
DETECTION defined by a grid of conductive traces according to an
embodiment;
CROSS-REFERENCE TO RELATED FIG. 3A is a diagram of an example of a detection system
APPLICATIONS 5 according to an embodiment;
FIG. 3B is an enlarged view of an example of the detection
This application claims the benefit of priority under 35 panel assembly shown in FIG. 3A;
U.S.C. §119(e) from U.S. Provisional Patent Application Ser. FIG. 4 is a sectional view of an example of a plurality of
No. 61/497,631 filed on Jun. 16, 2011, the contents of which detection layers according to an embodiment;
are incorporated herein by reference. 10 (cid:9) FIG. 5 is a sectional view taken along lines 5-5 of FIG. 3
according to an embodiment;
FIG. 6 is a side view of an example of a flexible detection
ORIGIN OF THE INVENTION
panel assembly according to an embodiment;
FIG. 7 is a flowchart of an example of a method of evalu-
The invention described herein was made in the perfor-
15 ating a structure according to an embodiment;
mance of work under a NASA contract and by employees of
FIG. 8 is a flowchart of an example of a method of detecting
the United States Government and is subject to the provisions
damage according to an embodiment; and
of Public Law 96-517 (35 U.S.C. §202), and may be manu-
FIG. 9 is an illustration of an example of a graphical user
factured and used by or for the Government for governmental
interface (GUI) according to an embodiment.
purposes without the payment of any royalties thereon or
20
therefore. DETAILED DESCRIPTION OF THE INVENTION
BACKGROUND OF THE INVENTION Embodiments of the present invention may provide a
method of detecting damages to surfaces. For example, the
1. Technical Field (cid:9) 25 exterior structure of an inflatable space platform such as a
Embodiments of the invention generally relate to damage spacecraft or habitat located in outer space. Damage caused
detection. More particularly, embodiments relate to the use of by impacts of foreign objects, e.g., micrometeorites, can eas-
a grid of conductive traces to detect damage to platforms such ily rupture the shell of the inflatable or habitation structure,
as inflatable spacecraft structures, rigid habitation structures, causing loss of critical hardware and/or life of the crew. While
other terrestrial inflatable structures, and composites. 30 not all impacts will have a catastrophic result, it can be advan-
2. Discussion tageous to identify and locate areas of the exterior shell that
Early versions of inflatable structures intended for use in have been damaged by impact so that repairs (or other provi-
outer space and habitation often relied upon the use of thin sions) can be made to reduce the probability of shell rupture
films to produce the structure's outer skin. More recently, and ultimate failure. Embodiments of the present invention
approaches to creating such inflatable structures utilize a 35 involve a system that may provide real-time data regarding
multilayer approach, with relatively thin layers separated by the health of the inflatable shell of a structure, specifically
thicker, more robust layers, providing a layered composite including data related to the location and depth of any impact
structure with significantly improved damage resistance. damage. Other embodiments include detecting damage to
Even though such composite structures are more robust, they aircraft, spacecraft, composite materials, and textiles. Still
are susceptible to penetration damage from micrometeorites 40 further embodiments involve detecting damage to interior
and other space debris. surfaces, non-inflatable structures, and other terrestrial inflat-
During launch and landing operations, plume ejecta can be able structures such as military shelters.
a significant source of damaging debris. Currently, the Embodiments of the present invention can also provide a
method for determining damage to inflatable structures uti- multi-dimensional damage detection system that identifies
lizes differential pressure systems, which tend to work better 45 both the precise location and extent of damage to an inflatable
if damage causes an actual leak. However, if the damage is structure. Incorporated into the embodiments may be related
relatively minor, it is more difficult to determine the extent of technology of detecting damage to thin films, including new
the damage. Minor damage can lead to more significant dam- methods of fabricating and testing new versions of conductive
age if undetected and not addressed as soon as possible. materials in thin-film layers that may be utilized in external
In an effort to detect such damage, very thin wires or 50 structures, solar arrays, windows, casings, and fabrics.
conductive traces or fibers may be embedded into the com- FIG. lA illustrates an inflatable spacecraft 10 including an
posite material. Such systems can be difficult to fabricate, exterior structure that may be susceptible to damage from
however, and may not be easy to connect together at the debris during launch, orbit, and/or landing. Accordingly, the
system level. The present invention provides new and novel exterior structure of the spacecraft 10 may be fabricated from
methods, systems, and apparatus for use in damage detection 55 a plurality of interconnected panels 12, wherein each panel 12
applications. has a plurality of detection layers separated from one another
by one or more detection layers. As will be discussed in
BRIEF DESCRIPTION OF THE DRAWINGS greater detail, the plurality of detection layers can form a grid
of conductive traces that may be monitored for electrical
The various advantages of the embodiments of the present 60 property changes. The detection of such electrical property
invention will become apparent to one of ordinary skill in the changes can enable advanced damage detection activities
art by reading the following specification and appended such as the generation of diagnostic and/or prognostic outputs
claims, and by referencing the following drawings, in which: with respect to the exterior structure of the inflatable space-
FIG. lA is an illustration of an example of an inflatable craft 10. Wherein the outputs can identify damage to indi-
spacecraft according an embodiment; (cid:9) 65 vidual panels 12 via a spatially oriented or globally posi-
FIG. 1B is an exploded view of an example of a layered tioned coordinate system with respect to the inflatable
shell of an inflatable habitat according to an embodiment; spacecraft 10. Furthermore, the specific damage site locations
US 9,233,765 B2
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on said individual panels 12 are determined by said panel's In a preferred embodiment, thin, conductive patterns are
grid of conductive traces. FIG. 1B demonstrates that the outer printed on one or more of a wide variety of substrates using a
shell/structure of a space habitat may include multiple layers. standard inkjet printer with several conductive inks. The sub-
FIG. 2 shows a detection pattern 14 that might be defined strates include, but are not limited to, polyimides, fluoropoly-
by a multi-layer grid of conductive traces. Several detection 5 mers, vinyl polymers, cotton fabrics, paper, and NOMEX. In
layers can be implemented, where alternate layers are designing the detection system, the number of detection lay-
arranged in an orthogonal direction with respect to adjacent
ers chosen may depend on the level of damage detection
layers. The orthogonal arrangement allows for pinpointing
detail needed. The damage will result in a change in electrical
the exact location of the damage to the surface of the struc-
properties in the grid of conductive traces which can be
ture. Moreover, multiple detection layers allow for the calcu- l0 detected utilizing the monitor 30, which may comprise a time
lation of the depth of the damage to the surface. Indeed, each
domain reflectometer, resistivity monitoring hardware,
detection layer may also include multiple known defect traces
capacitive measurement components, or other resistance-
to facilitate panel identification as well as damage zone deter-
based detection systems. More particularly, the multi-dimen-
mination, as will be discussed in greater detail. The illustrated
detection pattern 14 demonstrates that conductive traces of 15 sional damage detection system 24 can include a multiplicity
successive detection layers may be arranged perpendicular or of non-detection layers separated from one another by a mul-
angled to one another in order to provide the desired detection tiplicity of detection layers, with each of the detection layers
grid. For example, a first panel 16 has a detection pattern with being connected to the monitor 30 in order to provide details
a relatively high resolution, wherein a second panel 18 and a regarding the physical health of each individual detection
third panel 20 have a relatively low resolution. Thus, the first 20 layer. If damage occurs to any of the detection layers, a
panel 16 could be used in areas of an exterior structure that are change in the electrical properties of the damaged detection
particularly susceptible to damage (e.g., sensitive launch and/ layer(s) may also occur, and a response may be generated. For
or landing areas) or encompass particularly sensitive compo- example, real-time analysis of the responses may provide
nents of the spacecraft (e.g., navigational components, power details regarding the depth and location of the damage. More-
supply, etc.). Moreover, each of the first three panels 16, 18, 25 over, multiple damage locations can be detected, and the
20 also has a uniform resolution in the example shown. A extent (e.g., depth) of each damaged area can result in the
fourth panel 22, on the other hand, might have a non-uniform generation of prognostic information related to the expected
resolution, which may be used to target even smaller areas for lifetime of the layered composite system.
heightened detection sensitivity. In one example, traces are The illustrated detection system 24 can be easily fabricated
0.020-inches thick and separated from each other by 0.020 30 using commercial off-the-shelf (COTS) equipment and the
inches. detection algorithms may be updated as needed to provide the
FIGS. 3A and 3B illustrate a multi-dimensional detection level of detail needed based on the system being monitored.
system 24, wherein the system 24 generally includes a multi- Connecting the monitor 30 to the thin-film detection layers of
layered panel assembly 26 with a sensing panel 57 that is the panel assembly 26 may provide a method of monitoring
powered by a power supply 28 and communicatively coupled 35 any damage that may occur.
to a monitor 30. In some embodiments the monitor 30 may be For example, the monitor 30 can systematically output a
a computer monitoring device that can only receive com- test signal to the panel assembly 26 and manipulate the input
mands and/or data. In other embodiments the monitor 30 may data to determine a conclusion, wherein damaged trace/line
be a computer monitoring device that can send and receive and defect line numbers may be sorted in ascending order and
commands and/or data. And in further embodiments the 40 then grouped into individual data arrays according to layer.
monitor 30 may be a microcontroller or microprocessor The arrays may also be normalized so that each line number
embedded within the multi-layered panel assembly 26. is referenced from a particular range (e.g., 0-167). Once the
Wherein the damage detection data may be stored within the damaged and defect line numbers have been normalized, the
microcontroller or microprocessor for accessing at a later monitor 30 may calculate the damaged line-number-to-line-
date for eventual download and viewing on an external 45 number spacing. Damaged line numbers that occur sequen-
device. tially can be grouped together to form a damage zone. The
In one example, an organic inherently conductive polymer damage zone size may be calculated by determining the num-
may be used as a damage detection layer. For example, polya- ber of sequential lines found.
niline derivatives have been demonstrated to function well as Once the damage zone size is calculated, the monitor 30
a damage detection conductor in a thin-film coating configu- 50 may resolve the appropriate defect analysis state to execute.
ration having several thicknesses. Moreover, polyaniline In order to resolve the execution state, the monitor 30 may
coatings on polyethylenephthalate (PET) and KAPTON-H assume that the damage occurs on the panel assembly top
have performed successfully for damage detection. In addi- (i.e., outer) layer and traverses through each subsequent layer.
tion to polyaniline, carbon nanotube (CNT), metal nanopar- If damage does not occur on the top layer first, but rather on
ticle inks, and combinations thereof, thin films produced in 55 the inner layers only, the monitor 30 may reject and not
accordance with embodiments of the present invention may process the data.
be employed as conductors in thin-film configurations. In one example, the monitor 30 utilizes a state machine
In the illustrated multi-dimensional detection system 24, with five states, wherein each state represents the number of
two-dimensional detection layers of thin film may be used to layers of damage detected plus an idle state. The damage
form a layered composite, with thicker, non-detection layers 60 occurs in the proper order for the correct state to be per-
separating the detection layers from one another. The thin- formed. For example, if the embedded monitoring system
film detection layers can be formed of materials having a reports that damage occurred on only the top layer and the
conductive grid or striped pattern such as the pattern 14 (FIG. bottom layer, then the state performed is State 1. In such a
2) already discussed. The conductive pattern may be applied case, the data from the bottom layer may be ignored.
by a variety of methods including, but not limited to, printing, 65 (cid:9) State 0—Idle, default, no data is processed
plating, sputtering, solvent casting, photolithography, and State 1-Damage detected on top layer only
etching. State 2-Damage detected on the top two layers (1 & 2)
US 9,233,765 B2
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State 3 Damage detected on the top three layers (1, 2, & drawn to represent the broken sensing lines. In such a case,
3) the operator may generally know the damage area, but not
State 4-Damage detected on all four layers necessarily the exact location.
Damage detected on the top layer only may be the easiest to The second reason has to do with known defect lines (e.g.,
process. In such a case, the monitor 30 can calculate the 5 trace continuity signature information). Damaged line num-
x-coordinate based on the normalized damaged line number bers that occur sequentially can be grouped together to form
a damage zone, as already discussed. A single damage zone
multiplied by the spatial resolution of the grid (e.g., 0.04
can appear to be multiple damage zones if there are defect
inches). The y-coordinate may be set to zero because it is
lines that occur between a damaged line number sequence,
unknown since the damage did not penetrate to the second
io causing the pattern not to be sequential. In this case, the
layer. The monitor 30 may complete its operation by popu-
monitor 30 may determine if there are defects found in the
lating a damage attributes cluster array. When the software
zone, and if so, the damage zone size can be incremented
detects that the y-coordinate is equal to zero in the cluster
based on the number of defects found. There is a special
array, it can automatically draw a vertical color-coded line on
scenario for the defects case. If two damage zones occurred
the chart display object.
15 simultaneously and one of those zones penetrated an area
If damage is detected on two or more subsequent panel containing known defect traces and the other zone didn't
assembly layers, then the monitor 30 may begin a series of contain known defect traces, the monitor 30 may have suffi-
operations to determine the appropriate generalized scenario cient information to resolve the damage location and assign
for each state. There are numerous lower-level cases that the appropriate x- and y-coordinates. If two damage zones
occur in each generalized scenario. 20 exist and both have known defect traces or more than two
The following scenarios might be calculated for States 2-4. damage zones exist, the algorithm may be unable to resolve
Scenario #1: Damage Zone Array Sizes Equal 1 the location and color-coded vertical and/or horizontal lines
Since one damage zone is detected, the monitor 30 may can be drawn to represent the broken sensing lines. Again, the
pair the layer one damaged line numbers (x-coordinates) to monitor 30 may complete its operation by populating the
the layer two damaged line numbers (y-coordinates) to form 25 damaged attributes cluster array.
a coordinate pair. Since the damaged line numbers are sorted After the generalized scenarios have been executed and the
in ascending order, the lowest-value damaged line number in damaged attributes cluster array have been populated with the
most current information, the illustrated monitor 30 plots the
layer one (x) is paired to the lowest-value damaged line num-
damaged attributes cluster array data on a graphic chart dis-
ber in layer two (y). If the damage is symmetrical, the opera-
tor will observe on the chart graphic display object resolved 30 play object. If either x- or y-coordinate pair equals 0, then a
color-coded vertical or horizontal line may be plotted rather
color-coded points corresponding to damage depth layer;
than a point, wherein the line or point fill color may be
otherwise, whichever direction the number of damaged lines
determined by a damage depth layer value in the damaged
is greater (x or y) then vertical or horizontal lines will appear
attributes cluster array. For example, the layer damage color
to represent the extra broken sensing lines that could not be
35 code could be defined as below.
paired. The monitor 30 can complete its operation by popu-
Top Layer–white
lating the damaged attributes cluster array.
Second Layer--blue
Scenario #2: Damage Zone Array Sizes Are Equal but Greater Third Layer–yellow
Than 1 Bottom Layer–red
This scenario may occur for two reasons. First, multiple 40 (cid:9) In the illustrated example, a first plurality of inside con-
damage zones could be detected, which might happen when ductive pads 34 facilitate electrical connection to the conduc-
damage occurs simultaneously at different spots on the panel tive traces (e.g., horizontally arranged) of a first detection
assembly (i.e., micrometeoroid shower). The second reason layer, and a second plurality of inside conductive pads 32
has to do with known defect lines. Damaged line numbers that facilitate electrical connection to the conductive traces (ver-
occur sequentially are grouped together to form a damage 45 tically arranged) of a second detection layer. Where inside
zone. A single damage zone can appear to be multiple damage conductive pads 32 and 34 may be configured perpendicular
zones if there are defect lines that occur between a damaged to each other. Similarly, a first plurality of outside conductive
line number sequence, causing the pattern to not be sequen- pads 38 may facilitate electrical connection to the conductive
tial. In this case, the monitor 30 determines if there are defects traces (horizontally arranged) of a third detection layer, and a
found in the zone, and if so, the damage zone size may be 50 second plurality of outside conductive pads 36 can facilitate
incremented based on the number of defects found. The electrical connection to the conductive traces (vertically
monitor 30 can complete its operation by populating the arranged) of a fourth detection layer. Where outside conduc-
damaged attributes cluster array. tive pads 36 and 38 may be configured perpendicular to each
Scenario #3: Damage Zone Array Sizes Are NOT Equal other. The inside conductive pads 32, 34 and the outside
This scenario may occur for two reasons. First, multiple 55 conductive pads 36, 38, which may be disposed on a circuit
damage zones may be detected, which can happen when substrate 56 adjacent to the perimeter of the panel assembly
damage occurs simultaneously at different spots on the panel 26, can be used to interconnect panels with one another or to
assembly (e.g., micrometeoroid shower). In this particular connect panels to the monitor 30. Indeed, the monitor 30 may
scenario though, multiple damage zones may have been be coupled to the grid of conductive traces via a wireless link
detected on the top layer, while on layer two, there were fewer 60 (e.g., Bluetooth or Wi-Fi) or a wired link, and may even be
damage zones detected because all the damage detected on embedded into the panel assembly 26 itself. In one example,
the top layer didn't penetrate evenly through the panel assem- such an embedded monitoring system is capable of monitor-
bly. Therefore, the damage zone array sizes might not be ing the health of hundreds of sensing lines and reporting their
equal. If this is the reason, then the damaged line numbers status within seconds. Moreover, conductive traces of succes-
from each layer might not be resolvable because there may be 65 sive detection layers may be arranged substantially perpen-
insufficient information to say for certain the location. There- dicular to one another in order to achieve the desired detection
fore, color-coded vertical and/or horizontal lines could be grid, as already discussed.