| ||STATEMENT OF INTENT: Develop design tool
|| Objective: ||Develop a validated design tool to predict the onset of laser shock processing induced flaws.
|| Description: ||Laser shock processing (LSP), also known by any of several trade names, is finding increasing use in military and commercial turbine engines. This process has been used to dramatically increase the durability of turbine engines in the presence of service induced damage.
LSP employs small, shock-induced plastic strains to generate a state of compressive residual stress in the treated region. In some materials and component geometries, for some LSP conditions, small subsurface flaws can be induced by the process. Although these flaws may not be of critical size, they are considered extremely undesirable.
Currently, no physically based model is available that will predict the onset of LSP-induced cracking in turbine engine materials and geometries. A successful model will allow for rapid determination of the laser shock processing design space for a given alloy, microstructure, and geometry, without excessive empiricism.
|| ||PHASE I: Demonstrate capability of proposed model to predict onset of LSP-induced cracking in a relevant alloy in simple coupon configurations. Determine requirements for material databases. Populate database for one relevant alloy and microstructure. Develop plan to adapt model for other applications.
|| || ||PHASE II: Develop and demonstrate a prototype model for use in a commercial LSP design package. Validate approach on a targeted turbine engine application. Deliver model in the form of a user friendly, executable code or as a package that can be used with commonly available finite element modeling software. Demonstrate code validity for related shock problems, such as armor spallation.
|| ||DUAL USE COMMERCIALIZATION: Military application: Integrate design package into design systems at client laser shock processing providers and/or original equipment manufacturers (OEM’s). Commercial application: Commercial applications of the developed package are identical to military applications for the purposes of this topic.
|| References: ||1. P. Peyre and R. Fabbro, “Laser shock processing: a review of the physics and applications,” Optical and Quantum Electronics, Vol. 27, pp 1213-1229, 1995.
2. Allan H. Clauer and David F. Lahrman, "Laser Shock Processing as a Surface Enhancement Process," Proceedings of the Durable Surfaces Symposium, International Mechanical engineering Congress & Exposition, Orlando, FL November 5-10, 2000.
3. Montross, C. S., Tao Wei, Lin Ye, Graham Clark, and Yiu-Wing Mai, "Laser Shock Processing and its Effects on Microstructure and Properties of Metal Alloys: a Review." International Journal of Fatigue 24(10): pp 1021-1036, 2002.
|Keywords: ||laser shock processing (LSP), Residual Stress, Component Surface Treatments, Shock Mechanics|