Mitigation of Fretting Fatigue Damage in Blade and Disk Pressure Faces With Low Plasticity Burnishing

Abstract

Low plasticity burnishing (LPB) is now established as a surface enhancement technology capable of introducing through-thickness compressive residual stresses in the edges of gas turbine engine blades and vanes to mitigate foreign object damage (FOD). The “fatigue design diagram” (FDD) method has been described and demonstrated to determine the depth and magnitude of compression required to achieve the optimum high cycle fatigue strength, and to mitigate a given depth of damage characterized by the fatigue stress concentration factor, kf. LPB surface treatment technology and the FDD method have been combined to successfully mitigate a wide variety of surface damage ranging from FOD to corrosion pits in titanium and steel gas turbine engine compressor and fan components. LPB mitigation of fretting-induced damage in Ti–6Al–4V in laboratory samples has now been extended to fan and compressor components. LPB tooling technology recently developed to allow the processing of the pressure faces of fan and compressor blade dovetails and mating disk slots is described. Fretting-induced microcracks that form at the pressure face edge of bedding on both the blade dovetail and the dovetail disk slots in Ti-6-4 compressor components can now be arrested by the introduction of deep stable compression in conventional computer numerical control (CNC) machine tools during manufacture or overhaul. The compressive residual stress field design method employing the FDD approach developed at Lambda Technologies is described in application to mitigate fretting damage. The depth and magnitude of compression and the fatigue and damage tolerance achieved are presented. It was found that microcracks as deep as 0.030in.(0.75mm) large enough to be readily detected by current nondestructive inspection (NDI) technology can be fully arrested by LPB. The depth of compression achieved could allow NDI screening followed by LPB processing of critical components to reliably restore fatigue performance and extend component life.

Influence of normal load frequency on fretting fatigue behaviour by a critical plane-based approach

“…In the last decades, many researchers have focused on fretting fatigue behaviour of different materials, tested by considering both a constant normal load and in-phase fretting fatigue loading [35][36][37][38][39][40][41][42][43][44][45] more complex loading conditions generally affect in-service engineering components. In such a context, some papers concerning complex loading configurations have been recently proposed.…”

An Influence of Geometrical Parameters of the Lock of the Blade-Disc Joint on Stress in the FEA and DIC Methods

“…From the operation point of view, the resistance on highcycle fatigue plays an important role. Therefore, determination of the fatigue durability is considered in many research groups [4,7,10,11,12,15,19,23,29]. These authors analyze the fatigue durability of rotor elements at various operational stages containing additional working conditions: (Fig.…”

Low plasticity burnishing improves fretting fatigue resistance in bone-anchored implants for amputation prostheses

“…Several methods exist for inducing compressive residual stresses, examples are shot peening, laser peening, deep rolling and LPB [24]. The LPB method has documented success in increasing fatigue life in compressor turbine blades [25], structural aircraft aluminium [26], and orthopaedic hip implants with tapered interface connection [27]. The objective of this evaluation is to investigate the potential of LPB for fretting resistance and fatigue life improvement in press-fit cylindrical connection of bone-anchored implants for amputation prostheses.…”