Laser Shock Processing of thin Al2024-T351 plates for induction of through-thickness compressive residual stresses fields

• The problem of Laser Shock Processing (LSP) of thin metal sheets is discussed.
• LSP conditions for through-thickness compressive residual stresses fields are specified.
• Through-thickness residual stresses in 2 mm-thick Al2024-T351 plates are experimentally demonstrated.
• Excellent correlation of experimental results to numerical predictions is verified.
• Work is in progress to check the effectivity of induced RS's fields on crack growth retardation.

Laser Shock Processing (LSP) has been demonstrated as an emerging technique for the induction of residual stresses (RS) fields in sub-surface layers of relatively thick specimens. However, the LSP treatment of relatively thin specimens brings, as an additional consequence, the possible bending in a process of laser shock forming. This effect poses a new class of problems regarding the attainment of specified RS's depth profiles in the mentioned type of sheets, and, what can be more critical, an overall deformation of the treated component.The analysis of the problem of LSP treatment for induction of tentatively through-thickness RS's fields for fatigue life enhancement in relatively thin sheets in a way compatible with reduced overall workpiece deformation due to spring-back self-equilibration is envisaged in this paper.The coupled theoretical–experimental predictive approach developed by the authors has been applied to the specification of LSP treatments for achievement of RS's fields tentatively able to retard crack propagation on normalized specimens. A convergence between numerical code results and experimental results coming from direct RS's measurement is presented as a first step for the treatment of the normalized specimens under optimized conditions and verification of the crack retardation properties virtually induced.