Quantitative Gap Measurement

in Ceramic Armor Arrays

by Seth Ghiorse, Ashiq A. Quabili, Renée Schoch,

William E. Fallon, and R.J. Sciortino

ARL-TR-5303 September 2010

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Army Research Laboratory

Aberdeen Proving Ground, MD 21005-5069

ARL-TR-5303 September 2010

Quantitative Gap Measurement

in Ceramic Armor Arrays

Seth Ghiorse 

Weapons and Materials Research Directorate, ARL

Ashiq A. Quabili

SURVICE Engineering Co.

Renée Schoch 

Dynamic Science, Inc.

William E. Fallon and R.J. Sciortino

BAE Systems U.S. Combat Systems-Pennsylvania

Approved for public release; distribution is unlimited.
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Quantitative Gap Measurement in Ceramic Armor Arrays

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14. ABSTRACT

In order to reduce weight while maintaining ballistic performance, modern armored vehicles often use ceramic-based armor 

solutions. Ceramic solutions are typically made of a close-fitting periodic array of ceramic tiles, maintaining a specific gap 

dimension between the tiles. The gap separation distance is critical to the ballistic performance of the system and it is 

important to have a reliable means of quantitative inspection. This report presents results of a study of a non-destructive 

quantitative X-ray gap width measurement method commonly used to measure and inspect array gaps. It was found that this Xray method gives a good portrayal of array quality and gap widths, but that gap measurement accuracy likely can be improved. 

The X-ray method was found to skew gap width measurements higher, between 2 and 20%, and was dependent on image blur. 

An X-ray system designed specifically for gap measurement will significantly improve measurement accuracy. Obtaining such 

a system is recommended, with digital X-ray radiography being the preferred path forward.

15. SUBJECT TERMS

ceramic array, quantitative gap measurement, X-ray, non-destructive evaluation, armor

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Seth Ghiorse

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iii

Contents

List of Figures iv

List of Tables iv

Acknowledgements v

1. Introduction 1

2. Experimental Procedures 2

2.1 Fabrication of the Ceramic Tile Arrays...........................................................................2

2.2 Identification of Gaps......................................................................................................2

2.3 BAE Vernier Caliper Method..........................................................................................5

2.4 ARL Optical Loupe Method............................................................................................5

2.5 X-Ray Equipment and Imaging.......................................................................................6

2.6 Optical Loupe on X-ray Method .....................................................................................7

2.7 AxioVision Measurement Software on Digitally Scanned X-ray Film Images..............9

3. Results and Discussion 11

3.1 BAE1 Gap Measurements.............................................................................................11

3.2 BAE2 Gap Measurements.............................................................................................12

3.3 X-ray Measurement Methods Comparison ...................................................................13

3.4 Production Batch Comparison.......................................................................................14

3.5 Goal Versus Actual Gap Widths...................................................................................15

4. Conclusions 16

Appendix. Measured Gap Data 17

List of Symbols, Abbreviations, and Acronyms 29

Distribution 30
iv

List of Figures

Figure 1. Diagram of BAE1 tile array with gap numbers............................................................................ 3

Figure 2. Diagram of BAE2 tile array with gap numbers............................................................................ 4

Figure 3. BAE1 tile array............................................................................................................................. 5

Figure 4. BAE2 tile array............................................................................................................................. 5

Figure 5. X-ray setup. .................................................................................................................................. 6

Figure 6. Composite of six X-rays to form a single complete picture of BAE1.......................................... 7

Figure 7. Composite of nine X-rays to form a single complete picture of BAE2........................................ 8

Figure 8. Close-up of a sharp, measureable gap looking through the 7× loupe........................................... 8

Figure 9. Close-up of a blurry, immeasurable gap looking through the 7× loupe. ...................................... 9

Figure 10. Screenshot of a gap measurement on X-ray film done in AxioVision. .................................... 10

Figure 11. Zoomed screenshot of a gap measurement on X-ray film done in AxioVision........................ 10

Figure 12. Graph of BAE1 results, showing the gap widths measured using the four different 

methods. ............................................................................................................................................... 11

Figure 13. Graph of BAE2 results, showing the gap widths measured using the four different 

methods. ............................................................................................................................................... 12

List of Tables

Table 1. Summary of BAE1 data for all four methods. ............................................................................. 12

Table 2. Summary of BAE2 data for all four methods. ............................................................................. 13

Table 3. Comparison of array process batches BAE1 and BAE2.............................................................. 15

Table A-1. Data collected from BAE1....................................................................................................... 17

Table A-2. Data collected from BAE2....................................................................................................... 22
v

Acknowledgements

The authors thank Tom Deal and his team at the Aberdeen Test Center Industrial Radiography 

Facility, for performing all the X-rays and for their expertise and insights into X-ray testing.

The ceramic array test panels were provided by BAE Systems U.S. Combat Systems –

Pennsylvania as part of a collaborative research program funded by the U.S. Army 

Manufacturing Technology (ManTech) Program, and sponsored by the U.S. Army Research 

Laboratory (ARL) under Cooperative Agreement Number W911NF-05-2-0002.
vi

INTENTIONALLY LEFT BLANK.
1

1. Introduction

Weight reduction is highly desired across U.S. Army platforms and equipment. Armor is no 

exception to this, and ceramic-based armor is one common means of lowering armor weight 

while maintaining protection level. Ceramic-based armor is commonly made up of a periodic 

array of many tiles that cover the protected area. The gap width between the tiles is critical to 

ballistic performance. Accurate manufacturing control of the gaps, as well as reliable postmanufacturing gap inspection to assure the final product is within performance limits, is also 

necessary. This study addresses quantitative gap width measurement using post-manufacture Xray. X-ray is the only practical non-destructive test method available to make quantitative width 

measurements of the gaps, as the tile array layer is located in the armor interior where direct 

visual inspection and measurement of the final product is not possible.

In order to assess the quantitative X-ray measurement system used at the U.S. Army Research 

Laboratory (ARL), two experimental tile arrays were fabricated at BAE Systems U.S. Combat 

Systems-Pennsylvania, York, PA (BAE). These arrays were made with one side open and

uncovered so that baseline direct visual gap measurements could be made. The direct 

measurements from these arrays gave the accurate data needed to evaluate the efficacy of the Xray data.

Direct tile gap measurements were made on the processed arrays using two different methods. 

First, the gap widths were measured by BAE personnel using a vernier caliper. Second, the test 

arrays were sent to ARL where the same gaps were measured with a 7× optical loupe placed 

directly over the gaps. The tile arrays were then X-rayed in order to collect gap measurement 

data as it is normally taken from X-ray film.

In a target test coupon, the tile gaps are not accessible for direct measurement and must be 

measured from X-ray film. In this study, they were measured using two approaches. Initially, 

the gaps were measured from the films by using the same 7× loupe that was used for the direct 

visual measurements. Then, the gaps were measured in the normal manner, using scanned 

digital images of the film that were subsequently evaluated using AxioVision image 

measurement software (a product of Carl Zeiss, Inc.). The results from X-ray measurement 

methods were then compared with results of the direct measurement methods.
2

2. Experimental Procedures

2.1 Fabrication of the Ceramic Tile Arrays

The two arrays were made in duplicate process runs. Making duplicate arrays was done to get a 

rough sense of batch-to-batch variability. One surface of each of these arrays was intentionally 

kept exposed so that direct gap measurements could be made for use as baseline data. Each tile 

gap contained a spacer of cured graphite fiber/epoxy composite of average thickness 33 mils 

with a standard deviation of 3 mils. The graphite-tile arrays were packed tight using BAE’s 

automated array packer, which is a step in their Build-to-Print (BtP) manufacturing process, 

developed under the U.S. Army Manufacturing Technology (ManTech) Program for ground 

vehicle armor production1

Next, two layers of Cytec FM94 epoxy film adhesive were placed over the array, followed by a 

cured polymer composite cover. The entire assembly was then cured by applying the appropriate 

250 °F heat-pressure cycle.

.

2.2 Identification of Gaps

To organize the array for study, each gap of each tile array was numbered according to BAE’s 

collected data. Gaps from test array BAE1 were numbered from 23 to 205, as shown in figure 1. 

Test array BAE2 was numbered from 1 to 205, as shown in figure 2. While performing the 

measurements, the diagrams in figures 1 and 2 were referenced in order to record and associate 

each measurement with the appropriate gap.

 

1 Low Cost Ceramic Armor-Automated Processing of Ceramic Armor Laminate; ARL 

Cooperative Agreement No. W911NF-05-2-0002; BAE Systems U.S. Combat Systems-Pennsylvania.
3

Figure 1. Diagram of BAE1 tile array with gap numbers.
4

Figure 2. Diagram of BAE2 tile array with gap numbers.
5

2.3 BAE Vernier Caliper Method

All gaps were first measured at BAE-York using the vernier caliper method. The caliper was 

placed directly on top of each tile gap and the closest gauge thickness was recorded for the width 

of that gap. The accuracy of the caliper was 1.0 mil and the measurement was “eyeballed” under 

bright lighting to give a measurement resolution of approximately 2.0 mils. The nature of this 

eyeballed measurement method did not allow interpolation to get a finer resolution. This 

procedure was repeated for every gap on both test panels. The open side of test panels BAE1 

and BAE2 are shown in figures 3 and 4.

2.4 ARL Optical Loupe Method

At ARL, a 7× optical loupe was used with bright lighting directly on the tile arrays to measure 

each gap. The loupe had a measurement grid marked every 5.0 mils. By interpolating between 

the grid lines, the resolution of the loupe measurement was approximately 2.5 mils. As with the 

vernier caliper method, this was repeated for each gap on each panel.

Figure 3. BAE1 tile array.

Figure 4. BAE2 tile array.
6

2.5 X-Ray Equipment and Imaging

Target test coupons at ARL are routinely sent to be X-rayed at the Aberdeen Test Center 

Industrial Radiography Facility, which is co-located with ARL at Aberdeen Proving Ground

(APG), MD. This facility is well-equipped to maneuver and X-ray large, heavy armor test 

coupons. A diagram of the X-ray setup used for this study is shown in figure 5. The maximum 

beam voltage is 450 kV and the maximum current is 5 mA. The distance from the aperture to the 

tabletop is fixed at 80 in. The aperture opening can be varied from 2.5 mm to 5.5 mm.

Figure 5. X-ray setup.

The X-ray film pack is placed directly on the tabletop and the array test coupon is placed directly 

on the film with the tile array side of the armor coupon facing away from the film. The film used 

was wet-developing Kodak 400AA. The film pack used lead image intensifiers that were 

0.001-in thick and located immediately above and below the film.

For all the BAE1 and BAE2 X-rays taken, the voltage was set to 175 kV at maximum current

(5 mA). The exposure time was 13 s with the aperture opening set at 5.5 mm. Each target was

X-rayed by using six images of BAE1 and nine images for BAE2 (BAE2 was not trimmed to 

final size and had excess edge material, which made it bigger, requiring three more X-rays to 

complete its composite image). These film images were then digitally scanned and combined to 

form digital composite images of the entire tile arrays (figures 6 and 7).
7

2.6 Optical Loupe on X-ray Method

Wet film X-rays were taken of the BAE1 and BAE2 tile arrays using the equipment and setup 

described in section 2.5. To ensure coverage of every gap, multiple overlapping X-rays were 

taken of each array, as is routinely done when a target test coupon is X-rayed. Typically, many 

gaps are blurry on the film. These were excluded from the optical loupe data since meaningful 

measurements were not possible. Assembled X-ray images of BAE1 and BAE2 are shown in 

figures 6 and 7, respectively. A close-up of a sharp, measureable gap, as viewed through the 

optical loupe, is shown in figure 8. Figure 9 shows an example of a heavily blurred

immeasurable gap.

To measure the gaps, the X-rays were affixed to an X-ray lightbox with bright backlighting and 

the 7× loupe was used to take the measurements to the nearest 2.5 mils.

Figure 6. Composite of six X-rays to form a single complete picture of BAE1.
8

Figure 7. Composite of nine X-rays to form a single complete picture of BAE2.

Figure 8. Close-up of a sharp, measureable gap looking through the 7× loupe.
9

Figure 9. Close-up of a blurry, immeasurable gap looking through the 7× loupe.

2.7 AxioVision Measurement Software on Digitally Scanned X-ray Film Images

To measure the gaps using AxioVision, high resolution digitally scanned Digital Imaging and 

Communications in Medicine (DICOM) files of the X-rays were made. DICOM is an 

uncommon, very high resolution picture file format used in the medical field and the AxioVision 

software does not recognize these files. However, some of the DICOM picture resolution could 

be salvaged (about half) by using an intermediate image software translator called GNU Image 

Manipulation Program (GIMP). The GIMP software is capable of converting DICOM files into 

very large Tagged Image File Format (TIFF) files, which is a format that is compatible with 

AxioVision. The original DICOM files were 30.3 MB and 254 dpi. After GIMP translation and 

conversion to TIFF files, the final TIFF files used by AxioVision were 15.2 MB and 254 dpi.

These files were opened with AxioVision and, after setting the correct scaling, AxioVision’s 

length-measuring function was used to measure the width of each gap. The measurement 

resolution of an image in AxioVision was 3.8 mils. This error arises from the fact that each 

square pixel had an edge length of 3.8 mils. A screenshot and close-up of a measurement done 

in AxioVision is shown in figures 10 and 11.
10

Figure 10. Screenshot of a gap measurement on X-ray film done in AxioVision.

Figure 11. Zoomed screenshot of a gap measurement on X-ray film done in AxioVision.
11

3. Results and Discussion

3.1 BAE1 Gap Measurements

BAE1 results are summarized in figure 12 and table 1 (all measured raw data is compiled in the 

appendix). The gap size variation within the BAE1 tile array as determined by the four different 

measurement techniques is shown in figure 12. The direct optical measurement methods are 

represented by the red and blue curves. The red curve corresponds to the vernier caliper data 

while the blue curve represents the optical loupe data. The vertical axis corresponds to the 

frequency of a specific gap width value, while the horizontal axis corresponds to the range of gap 

widths. The bin width used was 5 mils.

The X-ray film methods show a wider range of variation in the gap width compared to the 

baseline direct visual measurement approaches. The indirect X-ray measurement methods are 

represented by the green and purple curves. The green curve indicates the results obtained using 

AxioVision software on the scanned X-ray film, while the purple curve corresponds to the 

optical loupe method applied to the X-ray film (where 29% of the gaps were measureable). Both 

of these methods can be used in actual practice to inspect and measure the array of a test target 

coupon, although the digitized AxioVision method is the one routinely used as it is a much more 

efficient process.

Figure 12. Graph of BAE1 results, showing the gap widths measured using the four

different methods. 
12

Table 1. Summary of BAE1 data for all four methods.

BAE1 Vernier Caliper on 

Array

7× Loupe-onArray7× Loupe on XRay FilmaAxioVision on XRay Images

Average gap size (mils) 33.6 34.8 35.4 38.8

Std. Dev. (mils) 0.83 3.73 3.71 4.52 a

29% of gaps measured

3.2 BAE2 Gap Measurements

BAE2 results are summarized in figure 13 and table 2. 7% of the gaps were completely obscured 

by epoxy resin and were not measureable. In figure 13, the gap size variation within the BAE2 

tile array is demonstrated by the same four measurement techniques. The direct measurement 

data are represented by the red and blue curves. The red curve corresponds to the vernier caliper 

data while the blue curve represents the loupe data. The vertical axis corresponds to the 

frequency of a specific gap width value, while the horizontal axis corresponds to the range of gap 

widths. The indirect measurement methods are represented by the green and purple curves. The 

green curve indicates the Axiovision on X-ray data while the purple curve corresponds to the 

loupe on X-ray data (where 53% of the gaps were measureable). Both of these methods show a 

wider range of variation in the gap width compared to direct approaches, as occurred in the 

BAE1 array.

Figure 13. Graph of BAE2 results, showing the gap widths measured using the four 

different methods.
13

Table 2. Summary of BAE2 data for all four methods.

BAE2 Vernier caliper 

on Array

7× Loupe-onArraya7× Loupe on XRay FilmbAxioVision on XRay Images

Average gap size (mils) 35.5 37.7 44.6 45.0

Std. Dev. (mils) 4.26 8.51 11.27 8.63 a 93% of gaps measured 

b 53% of gaps measured

3.3 X-ray Measurement Methods Comparison

Both X-ray methods produce data that give a useful qualitative and quantitative portrayal of the 

tile array gaps. The direct measurement baseline methods are more accurate than the indirect Xray methods and are the basis for evaluating the X-ray film methods, which are the methods that 

must be used when assessing an actual target coupon array. Use of a vernier caliper worked well 

as a baseline for determining the gap widths and was in excellent agreement with the direct 

optical loupe, as is seen in figures 12 and 13. However, since this method does not interpolate 

well and relied on eyeballing, it introduced an element of parallax error and, while it generated 

data that matched up well with the direct optical loupe baseline, the values recorded are 

somewhat biased toward discrete uniformity. Therefore, the more accurate baseline method used 

in this study for gap measurements was the direct method using the optical loupe. Due to the 

clear visibility of the measurement grid and the ability to objectively interpolate between the grid 

markings, this method gives a truer measurement. (A 7× magnification loupe was chosen for 

this study. It is noted that higher magnification loupes with more refined grids can be used with 

equal ease and would return even more accurate data with the same ability to interpolate.) For 

this reason, the direct optical loupe values were used as the preferred baseline for comparison.

By comparing results from direct and X-ray measurement methods, it is concluded that the 

average of the tile gap sizes can be estimated through X-ray methods; however, the level of 

accuracy for X-ray methods is open to discussion. In particular, gap distribution curves for Xray measurements result in positive shifts. This indicates that X-ray measurements skew the gap 

widths upward and overestimate them. Identifying and extracting a corrective scaling factor 

might be possible if enough data is gathered. If this is the case, the factor could be determined 

by further study and applied to the X-ray measurements to correct this systematic error and 

accordingly, the level of accuracy could be improved.

The gap measurement and variability remain essentially unchanged when the measurement 

method is changed from a loupe measurement off the X-ray film or is digitally scanned and 

measured on a computer monitor using the AxioVision software. This is important, as the digital 

method is a much more efficient means of acquiring this data. It also has the potential for 

measurement automation in the future. If good quality image scanning and measurement 

software is used, it is not necessary to measure gaps directly off the film to get equivalent results. 

The use of AxioVision (or other measurement software) as a measurement tool results in data 

that is as good as a direct reading off the film with a loupe. In addition, digitization of the image 
14

for measurement by the software results in a much higher number of readable gaps, significantly 

increasing the statistical confidence in the data.

The AxioVision software did a much better job of interpreting blur than was able to be done 

using the loupe and human eye alone. This is because the software could magnify the digital 

image down to the pixel level and discriminate gray levels much better than the human eye. For 

this reason, the software was able to get a consistent, objective measurement from every gap, 

compared to 29% of the gaps when the loupe was used directly on the film on BAE1 and 53% on 

BAE2. However, when dealing with blur, AxioVision is more consistent, but not necessarily 

more accurate.

3.4 Production Batch Comparison

Comparing the two data sets by batch, which is shown in table 3, gives some insight into the 

repeatability of the process itself, albeit from a very small sampling of only two process runs. 

The data clearly shows that the gap widths in the BAE1 array were both smaller and less variable 

than those of BAE2. This was true across all measurement methods: the vernier caliper method 

recorded an average width increase of 1.9 mils (5.6%), the loupe-on-array method recorded an 

average increase of 2.9 mils (8.3%), the loupe-on-film method recorded an average increase of 

9.2 mils (26.0%), and the AxioVision digital measurement method recorded an average increase 

of 6.2 mils (16.0%). The manufactured array quality of BAE1 is clearly better than that of BAE2 

even though the runs were duplicates. This does not mean that the BAE2 run was out of 

specification―it simply means it was different enough to be detected by these measurement 

methods. Looking at the loupe distribution curve in figure 13, it clearly shows two small outlier 

peaks near 50 mils and 70 mils. At this time, there are no production limits set to determine an 

acceptable range of gap widths. The batch data is valuable as it provides a snapshot of batch-tobatch variability of the array packing portion of the current BtP process.

Note that the direct measurement methods show the two runs as much more repeatable than the 

two X-ray methods, which both indicated much larger gaps width increases. These direct visual 

methods are much more accurate and were created to give a baseline for X-ray evaluation for this 

study. So these are the values that depict the variability between the BAE1 and BAE2 

production runs; the X-ray data should not be, and is not, used for this purpose.
15

Table 3. Comparison of array process batches BAE1 and BAE2.

BAE1 and BAE2

Comparison

Vernier Caliper 

on Array

7× Loupe-onArray7× Loupe on XRay FilmAxioVision on 

X-ray Images

BAE1 BAE2 BAE1 BAE2 BAE1 BAE2 BAE1 BAE2

Average gap size (mils) 33.6 35.5 34.8 37.7 35.4 44.6 38.8 45.0

Std. Dev. (mils) 0.83 4.26 3.73 8.51 3.71 11.27 4.52 8.63

3.5 Goal Versus Actual Gap Widths

This study afforded the opportunity to portray what can be expected when manufacturing 

ceramic armor arrays by a process such as the current BtP method. Essentially, this process 

packs the array tightly, then applies a compressive load around the perimeter to hold the array in 

place until bonding is complete, at which time the compressive frame is released. The goal 

would be for every gap to be 33 mils with a variability of zero. This, of course, is not realistic. 

The nature of the process does not allow the gaps to be less than the spacer width (in this study 

33 mils, on average), but certainly allows them to be larger. The two data sets in this study 

represent a first hard look at realistic deviations from the idealized case. This is a vitally 

important metric of ceramic armor as ballistic performance is very sensitive to gap widths.

Using the direct loupe data set as the true values of gap widths, it is seen that the actual average 

gap width of the BAE1 array was 1.8 mils above the goal, with a standard deviation of 3.7 mils. 

Moreover, it is important to consider the maximum gap (47.5 mils), as this represents the 

location of greatest ballistic vulnerability. So, all gaps on the array fall at or below 14.5 mils 

above the goal.

BAE2 was made in a separate processing run and represents the repeatability of the process. It 

processed to an actual average gap width which was 4.7 mils above the goal, with a standard 

deviation of 8.5 mils. Its maximum gap was 75.0 mils. All gaps in this array fall between 0.0 

and 42.0 mils above the goal. This is quite a difference between batches and underscores a need 

for non-destructive quality control measurements and setting acceptable limits to deviations from 

gap width goals.
16

4. Conclusions

The direct optical measurement methods used in this study served as an excellent means to 

measure actual gap widths and provided a baseline for comparison by which to evaluate the Xray measurements. In practice, direct measurement of gaps is not possible. X-ray measurement

is the only non-destructive evaluation (NDE) method available to give quantifiable values for 

gap widths, which are critical to ballistic performance of the ceramic tile array. This study 

shows that the X-ray methods give a good portrayal of array quality, but measurement accuracy 

can be improved. It was revealed that the X-ray method skews the gap width measurements 

higher, and that this skewing was not consistent (it varied on the order of 2 to 20% in this study). 

Since ballistic performance is sensitive to gap widths, it is important to have an accurate and 

reliable NDE quality control method that can be counted on to obtain correct values. It is 

strongly recommended that a new X-ray system, designed specifically for the accurate measure 

of tile gaps, be put in place.

A common issue with X-ray films is that there is often inconsistency in terms of sharpness across 

the overall area of an X-ray image. The X-ray images produced for this study demonstrate this 

problem. It is of interest to find a way to reduce or eliminate the number of blurred gaps while 

increasing the measurement accuracy on the X-ray images. Optical distortions are at work here 

that can be greatly reduced. Improvement in the resolution of the X-ray process and the film 

itself is what is needed to make X-ray measurement more accurate and less blurred. As noted 

above, appropriate equipment design is a key to improvement. A digital radiography system 

would appear to be the path forward.

This study has demonstrated that the current digital X-ray measurement method in use is just as 

accurate as a loupe measurement taken directly off the film. The resolution of the scanned 

images can be no better than the film they were scanned from. It has been shown that the 

subsequent digital measurement by AxioVision software does not degrade the measurement and 

even increases repeatability somewhat over the manual loupe method.
17

Appendix. Measured Gap Data

Table A-1. Data collected from BAE1.

Location 

ID

Vernier 

Caliper on 

Array 

(mils)

7× Loupeon-Array 

(mils)

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

23 34.0 32.5 35

24 34.0 32.5 35.0 33

25 35.0 35.0 34

26 34.0 35.0 30

27 33.0 20.0 32.5 31

28 34.0 42.5 41

29 34.0 27.5 40.0 30

30 34.0 47.5 54

31 33.0 35.0 41

32 33.0 40.0 39

33 33.0 35.0 36

34 33.0 40.0 39

35 36.0 40.0 38

36 34.0 40.0 43

37 36.0 35.0 37

38 34.0 35.0 40

39 33.0 35.0 35

40 34.0 35.0 40

41 33.0 37.5 43

42 34.0 37.5 43

43 36.0 35.0 40

44 34.0 40.0 43

45 35.0 32.5 41

46 34.0 32.5 36

47 34.0 35.0 38

48 34.0 35.0 35.0 35

49 34.0 30.0 40

50 37.0 40.0 47

51 36.0 45.0 52

52 35.0 30.0 36

53 33.0 40.0 42

54 33.0 35.0 41

55 35.0 35.0 38

56 34.0 35.0 35.0 38

* Blank entries represent immeasurable data points
18

Table A-1. Data collected from BAE1 (continued). 

Location 

ID

Vernier 

Caliper on 

Array 

(mils)

7× Loupeon-Array 

(mils)

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

57 34.0 35.0 40

58 34.0 34.0 35

59 35.0 33.5 38

60 34.0 33.5 32.5 36

61 34.0 30.0 35.0 39

62 33.0 30.0 39

63 34.0 40.0 37

64 34.0 32.5 35

65 35.0 30.0 44

66 33.0 35.0 35.0 38

67 33.0 35.0 49

68 34.0 34.5 35.0 37

69 33.0 35.0 39

70 34.0 30.0 37

71 34.0 32.5 36

72 34.0 37.0 42

73 35.0 40.0 40.0 42

74 33.0 37.0 42

75 33.0 35.0 35.0 38

76 34.0 37.5 35.0 42

77 33.0 35.0 41

78 33.0 35.0 37

79 34.0 35.0 35.0 40

80 34.0 35.0 32.5 37

81 32.0 35.0 30.0 38

82 33.0 35.0 34

83 32.0 30.0 35

84 34.0 35.0 42

85 33.0 35.0 35.0 40

86 34.0 32.5 32.5 39

87 34.0 35.0 43

88 33.0 35.0 37

89 33.0 32.5 42

90 33.0 35.0 35.0 38

91 33.0 32.5 38

92 33.0 32.5 32.5 36

93 33.0 35.0 43

94 34.0 40.0 42

95 33.0 45.0 52

* Blank entries represent immeasurable data points
19

Table A-1. Data collected from BAE1 (continued). 

Location 

ID

Vernier 

Caliper on 

Array 

(mils)

7× Loupeon-Array 

(mils)

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

96 34.0 30.0 43

97 33.0 35.0 43

98 33.0 40.0 42

99 33.0 32.5 39

100 33.0 35.0 41

101 33.0 35.0 35.0 38

102 33.0 32.5 38

103 33.0 35.0 35

104 33.0 30.0 37

105 35.0 32.5 35.0 47

106 33.0 35.0 48

107 34.0 40.0 44

108 34.0 40.0 43

109 35.0 35.0 30.0 42

110 34.0 35.0 42

111 33.0 30.0 36

112 34.0 32.5 35.0 37

113 34.0 32.5 31

114 34.0 32.5 35

115 33.0 32.5 32.5 34

116 33.0 35.0 40

117 34.0 37.5 37.5 39

118 33.0 35.0 42

119 33.0 35.0 40

120 32.0 32.5 40

121 33.0 32.5 35

122 33.0 32.5 40

123 33.0 35.0 35

124 34.0 40.0 39

125 34.0 35.0 37

126 34.0 40.0 36

127 34.0 42.5 38

128 34.0 32.5 34

129 34.0 35.0 37

130 33.0 32.5 36

131 33.0 35.0 35

132 33.0 32.5 35

133 33.0 35.0 36

134 33.0 37.5 37.5 37

135 33.0 30.0 38

136 33.0 32.5 36

* Blank entries represent immeasurable data points
20

Table A-1. Data collected from BAE1 (continued). 

Location 

ID

Vernier 

Caliper on 

Array 

(mils)

7× Loupeon-Array 

(mils)

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

137 33.0 35.0 36

138 33.0 40.0 44

139 33.0 30.0 50.0 58

140 33.0 30.0 42

141 34.0 37.5 35

142 33.0 35.0 35

143 33.0 35.0 37

144 33.0 32.5 35.0 39

145 34.0 32.5 34

146 32.0 30.0 34

147 34.0 32.5 34

148 33.0 32.5 35.0 34

149 33.0 32.5 35.0 37

150 33.0 35.0 37

151 33.0 35.0 33

152 33.0 30.0 35.0 32

153 34.0 35.0 36

154 35.0 32.5 30.0 35

155 35.0 35.0 41

156 35.0 30.0 32.5 36

157 33.0 35.0 40

158 33.0 30.0 36

159 34.0 32.5 32.5 37

160 34.0 35.0 38

161 33.0 35.0 40.0 42

162 34.0 30.0 40.0 34

163 34.0 30.0 37.5 40

164 33.0 35.0 42.5 44

165 33.0 32.5 41

166 33.0 32.5 44

167 33.0 35.0 35.0 36

168 33.0 35.0 37.5 40

169 33.0 35.0 38

170 33.0 35.0 32.5 33

171 34.0 35.0 37.5 34

172 34.0 30.0 35

173 35.0 32.5 30.0 37

174 35.0 40.0 35.0 39

175 35.0 35.0 40

176 34.0 37.5 34

177 33.0 35.0 36

* Blank entries represent immeasurable data points
21

Table A-1. Data collected from BAE1 (continued).

Location 

ID

Vernier 

Caliper on 

Array 

(mils)

7× Loupeon-Array 

(mils)

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

178 33.0 32.5 32.5 38

179 33.0 32.5 38

180 33.0 40.0 35

181 33.0 32.5 42

182 35.0 30.0 44

183 33.0 35.0 45.0 42

184 34.0 45.0 50

185 33.0 45.0 43

186 33.0 35.0 50

187 33.0 37.5 44

188 34.0 37.5 48

189 36.0 37.5 35.0 49

190 33.0 42.5 46

191 33.0 40.0 40

192 33.0 37.5 38

193 33.0 35.0 35.0 41

194 34.0 32.5 37

195 34.0 35.0 38

196 34.0 37.5 40

197 33.0 35.0 32

198 33.0 45.0 38

199 33.0 35.0 34

200 34.0 32.5 32.5 35

201 33.0 27.5 37.5 30

202 34.0 30.0 34

203 33.0 32.5 32.5 35

204 35.0 32.5 32.5 33

205 34.0 37.5 40.0 38

AVG 33.6 34.8 35.4 38.8

STD 0.83 3.73 3.71 4.52

* Blank entries represent immeasurable data points
22

Table A-2. Data collected from BAE2.

Location 

ID

Vernier 

Caliper on 

Array 

(mils)

7× Loupeon-Array 

(mils)*

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

1 33.0 37.5 39

2 31.0 35.0 37.5 37

3 32.0 35.0 40

4 33.0 37.5 43

5 33.0 40.0 42.5 38

6 33.0 40.0 48

7 32.0 37.5 42

8 33.0 62.5 57

9 42.0 67.5 70.0 65

10 45.0 60.0 65.0 62

11 48.0 67.5 72.5 71

12 48.0 60.0 65

13 49.0 62.5 71

14 47.0 60.0 67.5 64

15 49.0 60.0 65.0 63

16 43.0 70.0 67

17 45.0 65.0 72.5 76

18 44.0 70.0 75.0 69

19 48.0 75.0 85.0 79

20 49.0 55.0 62.5 58

21 46.0 50.0 55.0 51

22 41.0 37.5 44

23 33.0 37.5 40.0 38

24 32.0 30.0 45.0 37

25 32.0 32.5 41

26 32.0 30.0 32.5 36

27 34.0 35.0 41

28 34.0 35.0 44

29 34.0 37.5 39

30 33.0 48

31 33.0 40.0 39

32 33.0 40.0 50.0 47

33 34.0 32.5 46

34 34.0 50.0 50.0 49

35 34.0 40.0 40.0 38

36 33.0 47.5 54

37 45.0 40.0 42.5 45

38 35.0 45.0 52.5 50

39 36.0 42.5 46

40 34.0 50.0 48

* Blank entries represent immeasurable data points
23

Table A-2. Data collected from BAE2 (continued).

Location 

ID

Vernier 

Caliper on 

Array 

(mils) *

7× Loupeon-Array 

(mils)*

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

41 33.0 40.0 45.0 42

42 34.0 37.5 47.5 43

43 33.0 37.5 45.0 42

44 34.0 35.0 35.0 34

45 34.0 32.5 37.5 37

46 34.0 40.0 44

47 37.0 32.5 40.0 41

48 33.0 35.0 40.0 40

49 35.0 35.0 46

50 32.0 32.5 40.0 46

51 32.0 87.5 39

52 33.0 88

53 33.0 35.0 51

54 33.0 32.5 50

55 33.0 35.0 49

56 30.0 38

57 34.0 35.0 47.5 51

58 34.0 35.0 47

59 41.0 40.0 55

60 32.0 30.0 50

61 33.0 35.0 42

62 34.0 35.0 40

63 32.0 37.5 45.0 41

64 34.0 35.0 43

65 33.0 35.0 45

66 34.0 35.0 44

67 35.0 37.5 47.5 42

68 34.0 30.0 45.0 36

69 33.0 32.5 41

70 34.0 35.0 37.5 35

71 33.0 35.0 45

72 40.0 35.0 45

73 44.0 47.5 50.0 52

74 45.0 45.0 40

75 36.0 40.0 55.0 50

76 33.0 35.0 50.0 43

77 33.0 32.5 35.0 34

78 35.0 35.0 40

79 34.0 35.0 42.5 44

80 35.0 35.0 35.0 37

81 34.0 35.0 40.0 40

* Blank entries represent immeasurable data points
24

Table A-2. Data collected from BAE2 (continued).

Location 

ID

Vernier 

Caliper 

on Array 

(mils)

7× Loupeon-Array 

(mils)*

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

82 34.0 35.0 47.5 43

83 33.0 30.0 35.0 34

84 34.0 32.5 37.5 37

85 36.0 35.0 52.5 42

86 34.0 35.0 40.0 40

87 35.0 32.5 37.5 39

88 33.0 32.5 46

89 34.0 32.5 35.0 37

90 34.0 35.0 44

91 34.0 35.0 43

92 34.0 32.5 40.0 40

93 35.0 35.0 44

94 44.0 35.0 45.0 46

95 35.0 55.0 57

96 35.0 50.0 43

97 34.0 35.0 42.5 40

98 34.0 40.0 42.5 45

99 33.0 35.0 37.5 36

100 33.0 35.0 38

101 33.0 30.0 45.0 39

102 34.0 30.0 35.0 35

103 34.0 35.0 32.5 38

104 35.0 30.0 39

105 33.0 35.0 37.5 36

106 35.0 35.0 40.0 36

107 33.0 35.0 45.0 41

108 35.0 30.0 37.5 37

109 35.0 35.0 35.0 37

110 35.0 32.5 45

111 33.0 35.0 44

112 36.0 35.0 41

113 34.0 35.0 47

114 33.0 32.5 35.0 35

115 36.0 32.5 45

116 33.0 32.5 47

117 34.0 37.5 38

118 35.0 52

119 33.0 32.5 47

120 33.0 35.0 48

121 35.0 30.0 47

122 33.0 35.0 37.5 39

* Blank entries represent immeasurable data points
25

Table A-2. Data collected from BAE2 (continued).

Location 

ID

Vernier 

Caliper on 

Array 

(mils)

7× Loupeon-Array 

(mils)*

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

123 34.0 30.0 37.5 40

124 35.0 32.5 47

125 35.0 30.0 46

126 34.0 35.0 47

127 34.0 35.0 38

128 34.0 32.5 40.0 39

129 34.0 32.5 45

130 33.0 35.0 49

131 33.0 35.0 52

132 35.0 35.0 40.0 46

133 35.0 35.0 32.5 38

134 34.0 35.0 44

135 33.0 32.5 40.0 44

136 34.0 32.5 35.0 39

137 44.0 32.5 41

138 34.0 37.5 45.0 44

139 34.0 55.0 58

140 33.0 44

141 43.0 35.0 48

142 33.0 35.0 46

143 37.0 32.5 39

144 34.0 35.0 40.0 45

145 34.0 35.0 35.0 35

146 34.0 35.0 48

147 34.0 30.0 42

148 34.0 35.0 40.0 42

149 34.0 35.0 48

150 34.0 35.0 37.5 38

151 33.0 35.0 35.0 49

152 34.0 35.0 45

153 33.0 35.0 45

154 33.0 35.0 35.0 36

155 33.0 35.0 43

156 33.0 30.0 40.0 39

157 35.0 32.5 48

158 34.0 30.0 37.5 39

159 36.0 35.0 42

160 35.0 32.5 46

161 33.0 37.5 40.0 42

162 35.0 40.0 41

163 34.0 30.0 32.5 35

*

Blank entries represent immeasurable data points
26

Table A-2. Data collected from BAE2 (continued).

Location 

ID

Vernier 

Caliper 

on Array 

(mils)

7× Loupeon-Array 

(mils) *

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

164 33.0 40.0 37.5 38

165 35.0 32.5 37.5 40

166 33.0 35.0 42

167 34.0 35.0 39

168 34.0 35.0 40

169 33.0 35.0 35.0 36

170 33.0 35.0 35.0 35

171 34.0 35.0 44

172 36.0 35.0 42

173 34.0 35.0 40.0 38

174 35.0 35.0 32.5 36

175 34.0 35.0 40.0 40

176 34.0 35.0 37.5 38

177 37.0 35.0 37.5 39

178 34.0 32.5 44

179 34.0 32.5 43

180 33.0 32.5 32.5 40

181 34.0 35.0 40

182 33.0 40.0 45

183 33.0 57.5 60

184 33.0 52.5 52

185 33.0 32.5 46

186 34.0 45.0 52

187 33.0 42.5 42.5 44

188 33.0 47.5 50.0 46

189 35.0 45.0 47.5 55

190 34.0 47.5 56

191 34.0 45.0 56

192 33.0 37.5 51

193 34.0 35.0 40.0 41

194 34.0 57.5 62.5 59

195 34.0 55.0 55.0 53

196 34.0 50.0 58

197 33.0 40.0 51

198 38.0 52.5 65

199 42.0 40.0 44

200 40.0 35.0 39

201 45.0 35.0 45

202 48.0 30.0 37.5 38

203 48.0 35.0 40

* Blank entries represent immeasurable data points
27

Table A-2. Data collected from BAE2 (continued).

Location 

ID

Vernier 

Caliper on 

Array 

(mils)

7× Loupeon-Array 

(mils)

7× Loupe 

on X-ray 

Film (mils)*

AxioVision 

on X-ray 

Images 

(mils)

204 49.0 32.5 43

205 50.0 37.5 40.0 40

AVG 35.5 37.7 44.6 45.0

STD 4.3 8.51 11.27 8.63

* Blank entries represent immeasurable data points
28

INTENTIONALLY LEFT BLANK.
29

List of Symbols, Abbreviations, and Acronyms 

APG Aberdeen Proving Ground

ARL U.S. Army Research Laboratory

BAE BAE Systems U.S. Combat Systems-Pennsylvania, York, PA

BtP Build-to-Print

DICOM Digital Imaging and Communications in Medicine

GIMP GNU Image Manipulation Program

ManTech U.S. Army Manufacturing Technology Program

NDE non-destructive evaluation

TIFF Tagged Image File Format
NO. OF

COPIES ORGANIZATION

30

1 DEFENSE TECHNICAL

(PDF INFORMATION CTR

only) DTIC OCA

8725 JOHN J KINGMAN RD

STE 0944

FORT BELVOIR VA 22060-6218

1 DIRECTOR

US ARMY RESEARCH LAB

IMNE ALC HRR

2800 POWDER MILL RD

ADELPHI MD 20783-1197

1 DIRECTOR

US ARMY RESEARCH LAB

RDRL CIM L

2800 POWDER MILL RD

ADELPHI MD 20783-1197

1 DIRECTOR

US ARMY RESEARCH LAB

RDRL CIM P

2800 POWDER MILL RD

ADELPHI MD 20783-1197

1 DIRECTOR

US ARMY RESEARCH LAB

RDRL D

2800 POWDER MILL RD

ADELPHI MD 20783-1197

ABERDEEN PROVING GROUND

1 DIR USARL

RDRL CIM G (BLDG 4600)
NO. OF NO. OF

COPIES ORGANIZATION COPIES ORGANIZATION

31 

 1 RDECOM TARDEC 

 COMBAT VEHICLE ARMOR 

 DEVELOPMENT ATO–GROUND 

 SYSTEM SURVIVABILITY 

 ATTN RDTA RS/MS 263 S KLANN 

 6501 E 11 MILE RD 

 WARREN MI 48397-5000 

 1 RDECOM TARDEC 

 BLDG 200D 

 ATTN RDTA RS/MS 255 V GENDLIN 

 6501 E. 11 MILE RD 

 WARREN MI 48397-5000 

 2 BAE SYSTEMS–YORK 

 ATTN R SCIORTINO 

 ATTN W FALLON 

 BLDG 20 COMPOSITES LAB 

 1100 BAIRS RD 

 YORK PA 17408 

 1 BAE SYSTEMS–SANTA CLARA 

 ATTN D SCHADE 

 PO BOX 359 

 SANTA CLARA CA 95050 

 1 GENERAL DYNAMICS 

 LAND SYSTEMS 

 ATTN G TEAL 

 P.O. BOX 1800 

 WARREN MI 48090-1800 

 1 GENERAL DYNAMICS 

 LAND SYSTEMS 

 ATTN K TRAN 

 M/Z 435 01 24 

 6000 E 17 MILE RD 

 STERLING HEIGHTS MI 48313 

ABERDEEN PROVING GROUND

 56 RDRL LOA F 

 M ADAMSON 

 RDRL WM 

 J SMITH 

 RDRL WMM 

 J ZABINSKI 

 R DOWDING 

 J BEATTY 

 RDRL WMM A 

 M MAHER 

 S GHIORSE (6 CPS) 

 J WOLBERT 

 L HOLMES 

 H MAUPIN 

 

RDRL WMM B 

 M VANLANDINGHAM 

 B CHEESEMAN 

 C YEN 

 T BOGETTI 

 RDRL WMM C 

 J LA SCALA 

 R JENSEN 

 J ROBINETTE 

 RDRL WMM D 

 E CHIN 

 W GREEN 

 R BRENNAN 

 RDRL WMM E 

 M PEPI 

 T JESSEN 

 J CAMPBELL 

 M BRATCHER 

 J SANDS 

 RDRL WMM F 

 R CARTER 

 K DOHERTY 

 RDRL WMM G 

 A RAWLETT 

 RDRL WMP 

 P BAKER 

 S SCHOENFELD 

 RDRL WMP A 

 B RINGERS 

 RDRL WMP B 

 C HOPPEL 

 RDRL WMP C 

 T BJERKE 

 RDRL WMP D 

 J RUNYEON 

 B SCOTT 

 V HERNANDEZ 

 S HUG 

 M KEELE 

 D PETTY 

 RDRL WMP E 

 S BARTUS 

 M BURKINS 

 D GALLARDY 

 W GOOCH 

 D HACKBARTH 

 E HORWATH 

 M KLUSEWITZ 

 C KRAUTHAUSER 

 M LOVE 

 RDRL WMP F 

 N GNIAZDOWSKI 

 RDRL WMP G 

 N ELDREDGE 

 RDRL WML 

 M ZOLTOSKI
32

INTENTIONALLY LEFT BLANK.