Research in Engineering and Aviation

Residual Stress and Wave Reflectivity When Laser Peening Thin Curved Sections

November 2011

Author(s): Malik, A.S., Lai, X., Langer, K.

IMECE2011-62444, Proceedings of the 2011 ASME Congress, Nov.11-17, 2011, Denver, CO.

Abstract

Laser Peening is an emerging technology that shows promise for extending the fatigue life of special-purpose metal components in the aerospace, automotive, medical, manufacturing, and other industries.  While laser peening has been shown to extend the fatigue life of metal components such as turbine blades and other high value-added components, the technology is not yet understood well enough to deploy it cost-effectively, without extensive experimental testing, for widespread application in diverse industries.  Because laser peening can adversely affect fatigue life if the process parameters are not selected appropriately, identification of tamping layers, pulse energy densities, shot patterns, and other parameters is critical to the component geometry, material, and loading.   When laser peening thin sections, preliminary finite element studies indicate that reflectivity of shock waves can induces regions of residual stress or damage on opposing surfaces.  Through a series of finite element simulations, this work explores the effects of stress wave reflectivity on component life for thin, curved, 6061-T6 aluminum alloy sections.  The simulations are based on an 800 mJ, 5 ns pulsed, near-infrared laser, serves to define the pressure pulse boundary condition, and allow more reliable deployment of laser peening technology.