In materials science and material fatigue, a crack arrestor or rip-stop doubler is a structurally strong ring or strip of material which serves to contain stress cracking that could lead to catastrophic failure of a device.
The crack arrestor can be as simple as a thickened region of metal, or may be constructed of a laminated or woven material that can withstand deformation without failure.
Crack arrestors were used to reinforce the airplane hull of the de Havilland Comet following a series of catastrophic accidents related to structural design problems that were previously unknown.
References
Crack arrestor Wikipedia(Text) CC BY-SA