Determination of fiber orientation and Poisson's ratio of materials by digital speckle interferometry

Abstract

The project discusses the use of Speckle Interferometry for Non-Destructive testing of composite materials. The composite materials are prepared manually in various shapes/Types as per the requirement. Determination of various fiber orientations and Poisson's ratio of composite materials are done by optical NDT approach. NDT is done to detect the location of defects in composite samples. A new jig is designed for holding and loading of samples in Three point and Four point bending of composites. The results of the Bending tests are used to find the Poisson's ratio of the composites. Both In Plane and Out of Plane displacements are done. A small shear of about 7mm in the image plane is given and Shear Speckle Interferometry of composites is carried out. The loading of samples are done by Mechanical and Thermal loading means. The values of Young's Modulus, Poisson's ratio and Shear Modulus are also calculated for various fiber orientations. The relation between variations of fiber orientations and shift in Optical axis are clearly shown by graphical diagrams. The Shearographic system is also used to find the defects and study the fringe pattern of honeycomb and Woven structures.