Synchrotron Strain Mapping of the Residual Strain Distribution around Foreign Object Damage in Laser Shock Peened Ti-6AL-4V Alloy

2010 ◽  
Vol 652 ◽  
pp. 19-24 ◽  
Author(s):  
Suraiya Zabeen ◽  
Michael Preuss ◽  
Philip J. Withers ◽  
Sven Spanrad ◽  
Jie Tong ◽  
...  
Keyword(s):  
Residual Strain ◽  
Strain Distribution ◽  
Leading Edge ◽  
Foreign Object ◽  
Laser Shock ◽  
Residual Stress Field ◽  
Strain Mapping ◽  
Foreign Object Damage ◽  
Ballistic Impacts ◽  
Shock Peening

The current study investigates the effect of foreign object damage (FOD) on the pre-existing compressive residual stress field associated with laser shock peening (LSP) and its evolution upon combined LCF/HCF cycling. FOD was introduced onto an aerofoil-shaped specimen that had been previously LSP treated through ballistic impacts at angles of 0° and 45° to the leading edge. It is shown that the FOD notch created by 45° impact was asymmetric in shape and smaller in depth compared to that created at 0° impact. Significant through thickness compression was introduced parallel to the leading edge as a result of the LSP process. The residual strain distribution was mapped around the FOD notch by synchrotron X-ray radiation. The results show predominantly compressive stresses ahead of the notch, being greater for the 0 compared to 45 impact. No significant stress relaxation was observed after a combined (1000 HCF cycles superimposed on 1 LCF cycle) cycle.

A Novel Methodology for Detecting Foreign Object Damage on Compressor Blading

2019 ◽  
Author(s):  
Paul Voigt ◽  
Matthias Voigt ◽  
Ronald Mailach ◽  
Daniel Münzinger ◽  
Kimon Abu-Taa ◽  
...  
Keyword(s):  
Surface Defects ◽  
Learning Algorithm ◽  
Impact Damage ◽  
Leading Edge ◽  
Software Tool ◽  
Suction Side ◽  
Scanning System ◽  
Foreign Object ◽  
Small Surface ◽  
Foreign Object Damage

Abstract Foreign Object Damage (FOD) to compressor airfoils is a common problem in operating aircraft engines that occurs when objects or debris are sucked into the engines. Especially small surface defects or impact damage (100μm – 300μm depth) can be problematic, as it only becomes noticeable during engine maintenance process, but can have a strong influence on the fatigue strength and service life of individual airfoils. Usually the blade and vane inspection during maintenance is carried out by visual examinations. The inspection findings are individually assessed and as a result the airfoils are accepted, repaired or replaced. This manual inspection process has a significant optimization potential by the means of automatization. This paper presents a novel methodology to automatically detect FOD on compressor airfoils. For the investigation and validation, numerous used compressor blades and vanes were digitized on site with a high precision optical 3D scanning system. A first approach is based on a machine learning algorithm. The idea is the surface segmentation of the digitized airfoil into typical affected areas such as the leading edge (LE), trailing edge (TE), pressure side (PS) or suction side (SS), wherein irregularities during the segmentation can be an indication for FOD. For a second approach, the surface curvature of the airfoil is considered. Locally limited regions with high curvature and concave shapes are sought as an indication for FOD. The required parameters position and depth associated to the individual FOD are calculated in both approaches. The results of both approaches are compared to each other and are validated against the results of a commercial software tool, which uses the approach of digital stoning to create surface defect maps. Furthermore, the results are verified by manually examining the airfoil scans. In the case of relatively small FOD, both approaches generate meaningful results. In terms of larger damages and deformations, both approaches have difficulties detecting it. This problem can be compensated by parametrization of the scanned airfoils with a section based approach using NACA like profile parameters. Unusual changes of specific airfoil parameters (e.g. stagger angle and chord length) over the airfoils height can indicate large FOD or deformation.

Laser Shock Processing: Applications and Future Trends in U.S. Air Force Service

2005 ◽  
Author(s):  
M. J. Shepard
Keyword(s):  
Air Force ◽  
Damage Tolerance ◽  
The United States ◽  
Foreign Object ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
Current Application ◽  
Foreign Object Damage ◽  
Us Air Force ◽  
Shock Processing

To date, the United States Air Force is the largest end-user of laser shock processing services. Laser shock processing (LSP) is in successful day-to-day service and production for several USAF engine lines for increased foreign object damage tolerance. In this application LSP has yielded substantial increases in foreign object damage tolerance along with associated increases in safety. The history and current application of laser shock processing for US Air Force applications will be reviewed. Current and future USAF applications of laser shock processing and other surface treatments will be reviewed.

scholarly journals Residual stresses due to foreign object damage in laser-shock peened aerofoils: Simulation and measurement

2015 ◽  
Vol 82 ◽  
pp. 78-90 ◽  
Author(s):  
B. Lin ◽  
S. Zabeen ◽  
J. Tong ◽  
M. Preuss ◽  
P.J. Withers
Keyword(s):  
Residual Stresses ◽  
Foreign Object ◽  
Laser Shock ◽  
Foreign Object Damage

scholarly journals Influence of multiple laser impacts on thin leading edges of turbine blade

2019 ◽  
Vol 234 (1) ◽  
pp. 130-143
Author(s):  
M Ayeb ◽  
M Frija ◽  
R Fathallah
Keyword(s):  
Turbine Blade ◽  
Turbine Blades ◽  
Leading Edge ◽  
Laser Shock Peening ◽  
Experimental Investigations ◽  
Laser Shock ◽  
Special Effect ◽  
Shock Peening ◽  
Critical Components ◽  
Mechanical Surface

Laser shock peening is a mechanical surface improvement treatment used to enhance the fatigue life of critical components. This paper investigates the influence of multiple square laser impacts to study their special effect on the diverse mechanical behaviours of the thin leading edge surface of turbine blades. Most works existing in the literature have presented experimental investigations. The originality of our paper is to validate and numerically simulate the proposed model. Indeed, a 3D finite element method of a thin leading edge specimen, Ti–6Al–4V, of a turbine blade is numerically simulated using the ABAQUS software. The mechanical surface modifications (residual stresses, equivalent plastic strains and Johnson–Cook superficial damage) induced by the multiple square laser impact are examined in detail. The main purpose of this investigation is to determine the effects of single-sided and double-sided laser shock peening.

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