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.