1. SHUBHAM VERMA

2. Fracture Mechanism In Design And Failure Analysis PREPARED BY SHUBHAM VERMA ME-2 nd Roll No.:BT/ME/1601/020

3.  Introduction  Applied load or stress may be tensile or compressive in nature Fracture Mechanism In Design And Failure Analysis  Separation of solid into two or more pieces under applied load or stress  Fracture due to 1.Crack initiation 2.Crack propagation Fracture

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

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

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

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

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

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

10.  Mechanism of Ductile Fracture F F F F  Force applied in initial condition  Sudden Fracture without plastic deformation

11.  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

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

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

15. Questions…