1
C H A P T E R 1
Nature and Source of Residual
Stresses
“No materials, components or structures are completely free from residual stress.”
Viktor Hauk (1997) in Structural and Residual Stress Analysis by Non-Destructive Methods.
1.1 INTRODUCTION
Residual stresses are “locked-in” stresses that exist within a material without the presence of
any external loads. ey are “self-equilibrating,” that is, there exist within the material localized
areas of tensile and compressive stresses such that of the effects of the tensile areas balance those
of the compressive areas to give zero force and moment resultants. Figure 1.1 illustrates the
residual stresses within a block of heat-tempered glass. To improve its strength, the material
is manufactured such that its surfaces are in compression, balanced by tension in the interior.
Figure 1.1a shows the distribution of the horizontal normal stresses along a central vertical plane
and Figure 1.1b shows a photoelastic fringe pattern measured through the material depth.
(a) (b)
σ
Figure 1.1: Stress distribution in thermally toughened glass. (a) Horizontal stress profile on
a central vertical plane and (b) photoelastic stress measurement (adapted from Scafidi et
al. (2015)).
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.