Improved High Cycle Fatigue Damage Tolerance of Turbine-Engine Compressor Components by Low Plasticity Burnishing

Abstract

Significant progress has been made in the application of low plasticity burnishing (LPB) technology to military engine components, leading to orders of magnitude improvement in damage tolerance. Improved damage tolerance can facilitate inspection, reduce inspection frequency, and improve engine operating margins, all leading to improved military readiness at significantly reduced total costs. Basic understanding of the effects of the different LPB process parameters has evolved, and finite element based compressive residual stress distribution design methodologies have been developed. By incorporating accurate measurement of residual stresses to verify and validate processing, this combined technology leads to a total solution approach to solve damage problems in engine components. An example of the total solution approach to develop LPB processing of a first stage Ti-6Al-4V compressor vane to improve the foreign object damage tolerance from 0.002in.to0.025in. is presented. The LPB process, tooling, and control systems are described, including recent developments in real-time process monitoring for quality control. Performed on computer numerical control (CNC) machine tools, LPB processing is easily adapted to overhaul and manufacturing shop operations with quality assurance procedures meeting military and industry standards, facilitating transition to military depots and manufacturing facilities.