Corrosion fatigue crack growth studies were conducted on eccentrically-loaded single edge notch tension specimens made of SA 333 Gr. 6 and SA 516 Gr. 70 carbon steels in water environment. The experiments were conducted using a ±250 kN capacity Universal Testing Machine under constant amplitude sinusoidal loading at a test frequency of 0.50 Hz and stress ratio of 0.1. The fabrication of test specimens and the experiments were carried out based on ASTM E 647 and ASTM E 1820. The crack initiation and growth were monitored and images were captured by using a digital camera at regular intervals of fatigue cycles. By using these images, the length of crack was measured. The tests were terminated when the uncracked portion of the specimens was insufficient to take further load. Crack growth rate and stress intensity factor range values were evaluated at incremental values of loading cycles and crack length. Using the crack growth rate vs. stress intensity factor range plots, best fit curves following power law in the form of Paris' equation were obtained.

Diffuse optical tomography (DOT) is an imaging modality which utilizes an array of near infrared light source (830 nm) for tissue illumination. The multiple-scattered light is detected using a pinhole camera. There are three primary absorbers at this wavelength which includes, water, oxygenated and deoxygenated hemoglobin, all possessing relatively weak absorptions. This provides a spectral window through which we can attempt to localize absorption and scattering in the tissue. Current techniques in imaging involve use of ionizing radiation which cause harm to tissues. For better image quality, the dosage has to be increased which induces the risk of cancer. Hence, we aim to exploit the non-ionizing characteristic of near infrared radiation (NIR), a potentially harmless band to image soft tissues. In our proposed system we are reconstructing 3-D images from 2-D cone beam projections using Feldkamp, Davis and Kress (FDK) algorithm which is most widely used because of its effective spatial resolution and duration time. It can also handle truncated data in longitudinal direction. The object to be imaged is positioned on the turntable and is rotated at 180 degrees. A major requirement of the setup is to position the phantom at equal distance from the source and detector. Both the camera and the stepper motor are controlled using MATLAB and are synchronized to work simultaneously. During the initial trials we propose to develop a phantom using paraffin wax that mimics the soft tissue properties. Eventually, experimentation will be done with different phantom models to test the compatibility and efficiency of the algorithm developed.