Engineering Fracture Mechanics

Instructor: Prof. K. Ramesh, Department of Applied Mechanics, IIT Madras.

The course covers the basic aspects of Engineering Fracture Mechanics. Topics covered in this course include Spectacular failures that triggered the birth of fracture mechanics, Modes of loading, Classification as LEFM and EPFM, Crack growth and fracture mechanisms, Energy release rate, Resistance, Griffith Theory of fracture, Extension of Griffith Theory by Irwin and Orowan, R-Curve, Pop-in phenomena, Crack branching. Necessary and sufficient conditions for fracture, Stress and Displacement fields in the very near and near-tip fields, Westergaard, Williams and Generalised Westergaard solutions, Influence of the T-stress and higher order terms, Role of photoelasticity on the development of stress field equations in fracture mechanics, Equivalence between SIF and G, Various methods for evaluating Stress Intensity Factors, Modeling plastic zone at the crack-tip, Irwin and Dugdale models, Fracture toughness testing, Fedderson TMs residual strength diagram, Paris law, J-integral, HRR field, Mixed-mode fracture, Crack arrest methodologies.

Mod-01 Lec-01 EFM Course Outline.
Spectacular Failures.
Lessons from Spectacular Failures.
LEFM and EPFM.
Fracture Mechanics is Holistic.
Fatigue Crack Growth Model.
Crack Growth and Fracture Mechanisms.
Elastic Strain Energy.
Fracture Strength by Griffith.
Energy Release Rate.
Utility of Energy Release Rate.
Pop-in Phenomenon.
Displacement and Stress Formulations.
Forms of Stress Funcitons.
Airy's Stress Function for Mode-I.
Westergaard Solution of Stress Field for Mode-I.
Displacement Field for Mode-I.
Relationship between KI and GI.
Stress Field in Mode-II.
Mod-04 Lec-20 Generalised Westergaard Approach.
Mod-04 Lec-21 William's Eigen Function Approach.
Mod-04 Lec-22 Multi-parameter Stress Field Equations.
Mod-04 Lec-23 Validation of Multi-parameter Field Equations.
Mod-05 Lec-24 Discussion Session-I.
Evaluation of SIF for Various Geometries.
SIF for Embedded Cracks.
SIF for Surface Cracks.
Modeling of Plastic Deformation.
Irwin's Model.
Dugdale Model.
Fracture Toughness Testing.
Plane Strain Fracture Toughness Testing.
Plane Stress Fracture Toughness Testing continued.
Paris Law and Sigmoidal Curve.
Crack Closure.
Crack Growth Models.
J-Integral.
HRR Fields and CTOD.
FAD and Mixed Mode Fracture.
Crack Arrest and Repair Methodologies.
Mod-09 Lec-41 Discussion Session - II.