Experimental and Numerical Investigation of crack Inclusion Interaction

Patil, Samadhan N (2016) Experimental and Numerical Investigation of crack Inclusion Interaction. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

Composite material failure mechanism is linked to fundamental problem of matrix crack interacting with second phase inclusion. In this work, an experimental and numerical investigation of crack inclusion interaction is carried out. Several experimental techniques can be used to study crack inclusion interaction study. However among all experimental techniques, digital photoelasticity and digital image correlation techniques (DIC) are evolved as most preferred techniques to estimate the fracture parameters such as stress intensity factor (SIF). To estimate SIF using digital pho- toelasticity, an over-deterministic linear least square methodology is used. This methodology has been applied to two di�erent specimen con�guration, single edge notch bend (SENB) specimen and SENB speciemen with glass inclusion. Using ten-step method and adaptive quality guided phase unwrapping algorithm ,both isoclinic and isochromatic fringe order has been estimated over the entire model domain. This whole �eld data is used to estimate the SIF using an over-deterministic linear least square methodology. In case of photoelasticity stress �led equations are used. Using approach of Yoneyama's multi-parameter equation an over-deterministic linear least square method- ology is developed and further it is used to estimate SIF. In case of DIC displacement �eld equations are used. Experimentally collected data (principal stress displacement/ u,v displacement �eld) is then compared with the theoretically reconstructed stress/displacement �eld in the form of contour plots by varying number of parameters for visual comparison. Later, a numerical study of the crack inclusion interaction is carried out using FEA. An failure criteria based on based on radial stress criteria is considered for modeling the debonding of interfacial elements at inclusion matrix interface. The e�ects of parameters such as inclusion diameter, elastic modulus mismatch etc., on the SIF are studied. An extended �nite element method based simulation is carried out for crack propagation in both specimens. The SIF's determined experimentally are then compared with FEA for two di�erent load level and they are found to be in closed agreement.

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IITH Creators:

IITH Creators	ORCiD

Item Type:

Thesis (Masters)

Uncontrolled Keywords:

Digital photoelasticity, ten-step methods, isochromatic, Fringe order, Digital Image correlation, Single Edge, Notch bend specimen, Extended finite element method, TD698

Subjects:

?? sub4.9 ??

Divisions:

Department of Physics

Depositing User:

Team Library

Date Deposited:

03 Aug 2016 11:53

Last Modified:

03 Aug 2016 11:53

URI:

http://raiithold.iith.ac.in/id/eprint/2609