This document discusses residual stresses, which are stresses that remain in a solid material after the original cause of stress is removed. Residual stresses can be desirable or undesirable. Common sources of residual stresses include casting, welding, machining, heat treatment, and plastic deformation during bending, rolling, and forging. Two methods for imparting beneficial compressive residual stresses are laser peening and shot peening. Various techniques for measuring residual stresses are also outlined such as X-ray diffraction, ultrasonic methods, and the hole drilling strain gage technique.

1. RESIDUAL STRESSES
BY
KOUSHIK KOSANAM
1RV15ME052

2. INRODUCTION
Residual stress in a roll-formed hollow structural
section causes it to gape when cut with a band-
saw.
Residual stresses are stresses that remain in a
solid material after the original cause of the
stresses has been removed. Residual stress may
be desirable or undesirable. For example, laser
peening imparts deep beneficial compressive
residual stresses into metal components such as
turbine engine fan blades, and it is used
in toughened glass to allow for large, thin, crack-
and scratch-resistant glass displays
on smartphones. However, unintended residual
stress in a designed structure may cause it to fail
prematurely.

3. Casting
Welding
Machining
Heat treatment
Plastic deformation during bending, rolling and forging
COMMON SOURCES OF RESIDUAL
STRESSES

4. LASER PEENING
Laser wavelength is about
0.04 µinch (1 µm).
Pulse duration 10-50
nanoseconds.
Pulse energy 50-100
joules.
Beam diameter 0.2” (5
mm).

5. SHOT PEENING
• Shot peening is a cold working process used to
produce a compressive residual stress layer and
modify mechanical properties of metals and
composites.
• It entails impacting a surface with shot (round
metallic, glass, or ceramic particles) with force
sufficient to create plastic deformation

6. X-ray diffraction
Ultrasonic methods
Magnetic methods
Electronic Speckle Pattern Interferometry
Hole drilling and strain gage technique
Core Hole drilling and strain gage technique
MEASURING OF RESIDUAL STRESSES

7. Hole drilling strain gage procedure
1.Install a special three to six strain gage rosette at the
point where stresses are to be measured.
2.Wire the strain gages to a static strain indicator.
3.Attach and accurately position a drilling device over the
target of the rosette.
4.Balance the gage circuits.
5.Drill hole in increments, being careful not to generate
heat that would induce residual stresses.
6.Record strains after the strain indicator has stabilized.
7.Calculate stresses using strain data by means of
formulas reported in ASTM E 837-08
The hole drilling strain gage method

8.  Schiavone, G.; Murray, J.; Smith, S.; Desmulliez, M. P. Y.; Mount, A. R.; Walton, A. J. (2016-01-
01). "A wafer mapping technique for residual stress in surface micromachined films". Journal of
Micromechanics and Microengineering. 26 (9):
095013. Bibcode:2016JMiMi..26i5013S. doi:10.1088/0960-1317/26/9/095013. ISSN 0960-1317.
"Flexural Properties by Four-Point Bending ASTM D6272". ptli.com.
Relaxman1993 (13 September 2014). "Tutoriel Abaqus-Contrainte résiduelle dans une poutre /
Residual stress in a beam" – via YouTube.
G.S.Schajer Practical Residual Stress Measurement Methods. Wiley 2013, 7, ISBN 978-1-118-
34237-4.
Los Alamos National Laboratory – Contour Method. Retrieved on 19 June 20
REFERENCES

9. THANK YOU