slip line field method - presentation
DESCRIPTION
Slip line field method and its application in forming process Manufacturing Process Class - Final yearTRANSCRIPT
SS LIP LIP LL INE INE FF IELD IELD
MM ETHODETHOD AND ITS AND ITS
AA PPLICATION IN PPLICATION IN
FF ORMING ORMING
PP ROCESSROCESSGroup 1Group 1
(Roll No. 49,50,51,52)(Roll No. 49,50,51,52)
Slip ?
process which allows plastic flow to occur in metals , where the crystal planes slide past one another
Why ?
force required for the entire block of crystals to slide is very large
lower level of stress is required
Slip Lines ?P
β - line α - line
φ
Slip Line Field ?
Orthogonal networks of the lines of maximum shear stress
The slip line patterns above are very useful for analyzing plane strain deformation in a rigid-plastic isotropic solid
Slip Line Field ?
Slip-line field for compression between a pair of rough parallel platens
Slip Line Field Method
It is an approach used to model plastic deformation in plane
strain only for a solid that can be represented as a rigid-plastic
body.
Assumptions
Rigid-Plastic Material Response
no elastic deformation and perfect plastic deformation
Fig 1. Rigid Plastic Material Response
In deformations of practical interest one of the principal strains (say ) is zero
It is applicable to rolling , drawing and forging.
Plane Strain
EXAMPLES
Try to use Slip Line Field Method to solve some problems
To determine the value of force (P)
Rigid Punch Indenting a Plastic Solid
Solution:
Plane Strain Extrusion (Hill)
α
slip-line
slip-line
β
H 2H
30o
45o
45o
P
A
B
C
D
a
b E
F
e1
e2
Plane Strain Extrusion (Hill)
σ 22 σσ 11
τ
σkσ
σk
π/3k
nn
ab
Plane Strain Extrusion (Hill)@ a
@ b
resultant force acting on CD and AB
Thus required force P=
-2k
Double-Notched Plate In Tension
α slip-line slip-lineβ
α
P
P
α
a
AB
Double-Notched Plate In Tension@ a
@ b
REFERENCES
G K Lal , Introduction to Machining Science. http://solidmechanics.org/text/Chapter6_1/Chapter6_1.htm http://www.engin.brown.edu/courses/en222/Notes/sliplines/sli
plines.htm http://www.globalspec.com/reference/70308/203279/html-
head-chapter-9-slip-line-field-analysis
QUESTIONS?