1. A Seminar Report On Fracture Mechanism In Design And Failure Analysis
PREPARED BY
ABHISHEK KUMAR SHARMA
ME-3rd
Roll No.:

2. Introduction Fracture
Separation of solid into two or more pieces under applied load or stress
Applied load or stress may be tensile or compressive in nature
Fracture due to
Crack initiation
Crack propagation
Fracture
Fracture
Fracture Mechanism In Design And Failure Analysis

3. Principles of Fracture Mechanics
Quantitative study of failure is called fracture mechanics
Fracture mechanics is the relationship between
Material properties
Stress level
Presence of cracks/defects in material
Types of crack-propagating mechanisms
The aim is: “ design to prevent structural failure”
Intention is to allow better design we design, only works well if ……………fracture and inter-relationships and limitations.
Fracture Mechanism In Design And Failure Analysis

4. Classification Fracture Brittle Fracture Ductile Fracture
Fracture in material can be broadly classified in two main category;
Fracture
Ductile Fracture
Brittle Fracture
Fracture Mechanism In Design And Failure Analysis

5. Ductile Fracture Occurs after prolonged plastic deformation.
Crack initiates from formation of voids and propagates slowly.
Ductile  y < f
 yields before fracture
Characteristic stress-strain curve for ductile material
Ex: Aluminum and it’s alloy
Ex: Aluminum and it’s alloy
Fracture Mechanism In Design And Failure Analysis

6. Mechanism of Ductile Fracture
Original specimen
Necking
Crack Nucleation
Crack Growth
Shearing at surface
Fracture
Fracture Mechanism In Design And Failure Analysis

7. Shape of work piece in Ductile Fracture
In ductile fracture Cup and Cone shape occurs
Cup
Cone

8. Brittle Fracture
Failure of material due to rapid rate of crack propagation
Negligible plastic deformation occurs
Brittle  y > f
 fractures before yielding
Characteristic stress-strain curve for brittle material
Ex: Grey Cast Iron
Fracture Mechanism In Design And Failure Analysis

9. F F F F Mechanism of Ductile Fracture
Force applied in initial condition F F
Sudden Fracture without plastic deformation
Sudden Fracture without plastic deformation F F

10. Shape of work piece in Brittle Fracture
Does not occurs any cup and cone shape
work piece breaks with a rough flat surface
Flat Rough Surface

11. Conditions/Modes of Fracture
Excessive elastic deformation
Excessive loading condition
Fatigue
Creep formation
Torsion
Elastic buckling
Strain rate
Elastic buckling
Fracture Mechanism In Design And Failure Analysis

12. Methods of protection against Fracture
Analysis of Design
Selection of material
Chemical composition
Heat treatment introduces compressive stress
Surface treatment (involves Etching and Sizing)
Selection of material
Fine grain control
Fracture Mechanism In Design And Failure Analysis

14. Questions…