Investigations into slope and curvature fringe formation using digital speckle shear interferometry
Shearography is an interferometric technique that enables real-time, non-contact and fullfield measurement of surface displacement derivatives to overcome the limitations of holographic interferometry techniques. This technique is highly efficient for nondestructive testing (NOT) of many in...
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
2015
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/10356/64811 |
| _version_ | 1826123206740672512 |
|---|---|
| author | Sembhu Sundarnath Amarlal |
| author2 | Murukeshan Vadakke Matham |
| author_facet | Murukeshan Vadakke Matham Sembhu Sundarnath Amarlal |
| author_sort | Sembhu Sundarnath Amarlal |
| collection | NTU |
| description | Shearography is an interferometric technique that enables real-time, non-contact and fullfield
measurement of surface displacement derivatives to overcome the limitations of
holographic interferometry techniques. This technique is highly efficient for nondestructive
testing (NOT) of many industrial materials such as composites to disclose the
defects in an object by identifying defect-induced deformation anomalies which are
pertinent to structural weakness. In this project, shearography based NOT studies were
conducted with the designed circular diaphragm samples under defect and defect free
conditions using the developed shearography system. Defect-induced changes of the
fringe patterns in honeycomb panels with and without defect under thermally loaded
conditions were also studied. The first derivative of the displacement gradient known as
shear fringes were digitally processed by computer integrated software to extract curvature
fringes by adopting Fast Fourier Transformation (FFT) method. Different image
processing based contrast enhancement schemes were applied on the acquired shear fringes
prior to compute second order derivative (curvature fringes). The effect of shearing and
the defect detection capability of shearography system have also been investigated. |
| first_indexed | 2024-10-01T06:00:52Z |
| format | Thesis |
| id | ntu-10356/64811 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T06:00:52Z |
| publishDate | 2015 |
| record_format | dspace |
| spelling | ntu-10356/648112023-03-11T17:00:16Z Investigations into slope and curvature fringe formation using digital speckle shear interferometry Sembhu Sundarnath Amarlal Murukeshan Vadakke Matham School of Mechanical and Aerospace Engineering DRNTU::Engineering::Mechanical engineering Shearography is an interferometric technique that enables real-time, non-contact and fullfield measurement of surface displacement derivatives to overcome the limitations of holographic interferometry techniques. This technique is highly efficient for nondestructive testing (NOT) of many industrial materials such as composites to disclose the defects in an object by identifying defect-induced deformation anomalies which are pertinent to structural weakness. In this project, shearography based NOT studies were conducted with the designed circular diaphragm samples under defect and defect free conditions using the developed shearography system. Defect-induced changes of the fringe patterns in honeycomb panels with and without defect under thermally loaded conditions were also studied. The first derivative of the displacement gradient known as shear fringes were digitally processed by computer integrated software to extract curvature fringes by adopting Fast Fourier Transformation (FFT) method. Different image processing based contrast enhancement schemes were applied on the acquired shear fringes prior to compute second order derivative (curvature fringes). The effect of shearing and the defect detection capability of shearography system have also been investigated. Master of Science (Precision Engineering) 2015-06-04T06:54:19Z 2015-06-04T06:54:19Z 2014 2014 Thesis http://hdl.handle.net/10356/64811 en 84 p. application/pdf |
| spellingShingle | DRNTU::Engineering::Mechanical engineering Sembhu Sundarnath Amarlal Investigations into slope and curvature fringe formation using digital speckle shear interferometry |
| title | Investigations into slope and curvature fringe formation using digital speckle shear interferometry |
| title_full | Investigations into slope and curvature fringe formation using digital speckle shear interferometry |
| title_fullStr | Investigations into slope and curvature fringe formation using digital speckle shear interferometry |
| title_full_unstemmed | Investigations into slope and curvature fringe formation using digital speckle shear interferometry |
| title_short | Investigations into slope and curvature fringe formation using digital speckle shear interferometry |
| title_sort | investigations into slope and curvature fringe formation using digital speckle shear interferometry |
| topic | DRNTU::Engineering::Mechanical engineering |
| url | http://hdl.handle.net/10356/64811 |
| work_keys_str_mv | AT sembhusundarnathamarlal investigationsintoslopeandcurvaturefringeformationusingdigitalspeckleshearinterferometry |