Novel Confinement Possibility for Laser Shock: Use of Flexible Polymer Confinement at 1064 nm Wavelength

Abstract

Through the years, laser shock peening became a treatment of choice in the aerospace industry to prolong the life of certain critical pieces. Water flow is commonly used as a confinement to improve the process capability but some applications cannot allow for water presence in the area of interest. In a previous article, an alternative to the water confinement was presented, a flexible polymer confinement was used and demonstrated the production of pressures equivalent to the water configuration treatment. However, laser parameters have been restricted to a wavelength in the visible range at 532 nm. In this paper, the study is extended to 1064 nm which is commonly used in LSP applications and with two different pulse durations. A 1064 nm near infra-red laser is used to do pressure characterization of shots with polymer confinement through Velocity Interferometer System for Any Reflector (VISAR) measurements coupled with Finite Element Modelling on Abaqus software. The results show that the pressures produced by the confinement is slightly lower with the 1064 nm wavelength, similar to what is observed with the classic water confined regime when switching from 532 nm to a near infra-red wavelength. Nevertheless, the high level of pressure produced by laser shock under the polymer confinement configuration allows for the treatment of common types of metal alloys used in the aerospace industry. Although the use of such a confinement has yet to be applicable to peening setups, it has already uses in some single shot configurations such as LasAT where it allows the avoidance of the water flow optimization.

Modeling of multi-edge effects in the case of laser shock loadings applied on thin foils: Application for material characterization of aluminum alloys

“…1. Moreover, Anderholm proved that it was possible to increase the pressure delivered through a laser shock up to six times compared to the direct configuration by confining the plasma using any transparent medium to the laser wavelength 16,17 such as water 15,18 or solid polymers 19,20 for the same laser intensity.…”