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Date: 10-04-2007

3D Computed Tomography Reconstruction

for Solid Rocket Motors

using Digital Radiography System

S.Vibinkumar, Dr.V.R. Ravindran, M.K. Suresh, C.Sreelekshmi, Dr.M.C. Santhoshkumar

Dept. of Physics, National Institute of Technology, Trichirappalli 620 015Rocket Propellant Plant, Vikram Sarabhai Space Centre,

Thiruvananthapuram 695 022 e.mail: vr_ravindran@vssc.org

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

CT Imaging PrincipleDetails of Data AcquisitionCT Experimental Setup using DR systemData Analysis and CorrectionsCT Reconstruction3D CT Visualization

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

Computed tomography: The process of imaging a cross sectional plane or Slice through

an object

Mathematically equivalent to the value along

the radial line through a 2D Fourier

Transform of the original distribution Slice

Theorem

P t, x, y dsL

FourierTransform

Frequency DomainSpatial Domain

Radon Transformation

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

Collection of data from DR System

Projections data Radon Transform

Added suitable filter function

Fourier Transform obtained 1-D projection data

Mathematically equivalent to the value along the radial line through

a 2D Fourier Transform of the original dist ribut ion Slice Theorem

Repeat the process for projection data from all angles, to obtain a

2-D Fourier Transform of the object distribution in polar coordinate

Take the Inverse 2-D Fourier Transform of the polar data array.

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

Specimen : RH560 Igniter Motor - Dia 70mm Length 324mm

Projection Image Acquire : Digital Radiography, 450kV X-Ray m/c,

Flat panel Detector, 4 Axis manipulator

Number of Projection : 180

Rotation Pitch : 1 degree

Projection image size : 512 x 512 (16 bit). TIFF

Workstation : NDTF/RPP/VSSC

Software : MATLAB

CT Reconstruction Technique : Filtered Backprojection

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

Electro

n

s

-

+

450KV

X-ray M/c

Flat Panel Detector

Y

Z

X

R

4 Axial

Manipulator

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

DR Image of Nozzle end

Image Size ; 200 x 70 mm

DR Image of Head end

Image Size ; 200 x 70 mm

Gap in charging resin

between motor case &

resin

Gap in charging resin between

motor case & grain

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

120 Projections (1.50) 180 Projections (10)

3 Projections (600) 12 Projections (150) 60 Projections (30)

CT Reconstruct ion improves with

the number of projections

The arti facts are to be removed by

filtering techniques to improve the

image quality

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

Before image correction

After image correctionCT Image

CT Image

Sinogram

Sinogram

Intensity Distribution

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

CT Imagesinogram showing the shift

Data showing artifact due to object shift during rotation

Software correction applied to rectify the problem

Sinogram with corrected data CT Image

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

CT image at A

showing defectSinogram at A

DR- Image at regionA

CT image at BSinogram at B

DR- Image at region B

B

A

DR Image

Gap Between

Case & Grain

A

B

Reconstruction at Selective portions

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

3D CT cross sectional image

CT image

DR image of ROI

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

DR Image

3D-CT Top View

3D-CT

Dissected Views

3D-CT Top View

Defect

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

Circumferential Length

Width

Height

Radial Distance

Nature of defect clearly identified

Accuracy of experimental measurement up to 300 microns is achieved

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Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.

Ensure the high product Quality and Reliability through CT

Developed CT reconstruction scheme using Matlab software

for SRMs and also suitable for other industr ial applications.

Successfully used FDP system for Tomography Reconstruct ion

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Thank You

Non Destructive Testing, Department of Physics , National Institute of Technology, Trichirappalli, India 620015.