Role of foreign-object damage on thresholds for high-cycle fatigue in Ti-6Al-4V

2000 ◽  
Vol 31 (6) ◽  
pp. 1571-1583 ◽  
Author(s):  
J. O. Peters ◽  
B. L. Boyce ◽  
A. W. Thompson ◽  
R. O. Ritchie ◽  
O. Roder
Keyword(s):  
High Cycle Fatigue ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Foreign Object Damage

The Effect of Foreign Object Damage on Compressor Blade High Cycle Fatigue Strength

2017 ◽  
Author(s):  
Benjamin Hanschke ◽  
Thomas Klauke ◽  
Arnold Kühhorn
Keyword(s):  
Fatigue Strength ◽  
Service Sector ◽  
High Cycle Fatigue ◽  
Compressor Blade ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Stress Concentrations ◽  
Foreign Object Damage ◽  
Input Parameters ◽  
Aero Engines

For a considerable amount of time blade integrated disks (blisks) are established as a standard component of high pressure compressors (HPCs) in aero engines. Due to the steady requirement to increase the efficiency of modern HPCs, blade profiles get thinned out and aerodynamic stage loading increases. Ever since, aerofoil design has to balance structural and aerodynamic requirements. One particularity of aero engines is the possibility to ingest different kinds of debris during operation and some of those particles are hard enough to seriously damage the aerofoil. Lately, a growing number of blisk-equipped aero engines entered service and the question of foreign object damage (FOD) sensitivity relating to compressor blade high cycle fatigue (HCF) has emerged. Correct prediction of fatigue strength drop due to a FOD provides a huge chance for cost cutting in the service sector as on-wing repairs (e.g. borescope blending) are much more convenient than the replacement of whole blisks and corresponding engine strips. The aim of this paper is to identify critical FOD-areas of a modern HPC stage and to analyze the effects of stress concentrations — caused by FOD — on the fatigue strength. A process chain has been developed, that automatically creates damaged geometries, meshes the parts and analyses the fatigue strength. Amplitude frequency strength (af-strength) has been chosen as fatigue strength indicator owing to the fact, that amplitudes and frequencies of blade vibrations are commonly measured either by blade tip timing or strain gauges. Furthermore, static and dynamic stress concentrations in damaged geometries compared to the reference design were computed. A random variation of input parameters was performed, such as the radial damage position at blade leading edge and damage diameter. Based on results of the different samples, correlations of input parameters and the fatigue strength drop have been investigated. Evaluation shows a significant mode dependence of critical blade areas with a large scatter between drops in fatigue strength visible for mode to mode comparison. Keeping in mind the necessity of fast response times in the in-service sector, FOD sensitivity computations could be performed for all blade rows of the HPC — including the analysis of possible borescope blending geometries — in the design stage. Finally, the actual amplitude frequency levels (af-levels) of the modes excited during operation have to be appropriately taken into consideration. For example, a pronounced af-strength drop due to a FOD may not be critical for safe engine operations because the observed mode is excited by small af-levels during operation. Hence, the endurance ratio — a quotient of af-level and af-strength — is used as assessment criterion.

scholarly journals Prediction of High-Cycle Fatigue Performance of 1Cr11Ni2W2MoV Stainless Steel Plate after Foreign Object Damage

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhenhua Zhao ◽  
Lingfeng Wang ◽  
Chao Liu ◽  
Lulu Liu ◽  
Wei Chen
Keyword(s):  
Stainless Steel ◽  
Flat Plate ◽  
Crack Growth ◽  
High Cycle Fatigue ◽  
Fatigue Cracks ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Worst Case ◽  
Foreign Object Damage ◽  
Damage Depth

High-cycle fatigue (HCF) properties of 1Cr11Ni2W2MoV stainless steel impacted by a high-speed steel ball were studied by the foreign object damage (FOD) test and HCF test. The results show that the damage depth Z has the most obvious effect on the HCF limit of notched flat plate specimens, and the fatigue limit decreases with the increase of depth Z . The microcharacteristics of the FOD notch and HCF fracture of 1Cr11Ni2W2MoV stainless steel were observed by a scanning electron microscope (SEM). The results show that the microdamage features such as plastic deformation, loss of material, and microcracks promote the initiation and propagation of fatigue cracks, and the fatigue source area lies near the root of the notch. The Peterson formula and Worst Case Notch (WCN) mode were used to predict the HCF limit of flat plate specimens after FOD. The crack growth threshold was obtained by the crack growth test. The results show that the prediction results of both methods are conservative. For the notch with damage depth Z < 1  mm, the prediction accuracy of the WCN model is higher ( error   range < 30 % ). For the notch with damage depth Z > 1  mm, the prediction results of both methods have large errors (>30%) with the WCN model being slightly more accurate.

Improving Corrosion Fatigue and Damage Performance of 410 Stainless Steel via LPB

2012 ◽  
Author(s):  
Douglas J. Hornbach ◽  
Jeremy E. Scheel
Keyword(s):  
Stainless Steel ◽  
Residual Stresses ◽  
Corrosion Fatigue ◽  
Shot Peening ◽  
High Cycle Fatigue ◽  
Damage Tolerance ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Foreign Object Damage ◽  
Compressive Residual Stresses

Stress corrosion cracking (SCC) and corrosion fatigue (CF) of 12% Cr stainless steel components can lead to reduced availability of steam turbines (ST). Significant operation and maintenance (O&M) costs are required to protect against CF and SCC in both aging and new higher efficiency ST systems. Shot peening has been used to reduce the overall operating tensile stresses, however corrosion pits, foreign object damage (FOD), and erosion can penetrate below the relatively shallow residual compression providing initiation sites for SCC and CF. A means of reliably introducing a deep layer of compressive residual stresses in critical ST components will greatly reduce O&M costs by improving CF life, increasing damage tolerance, reducing SCC susceptibility, and extending the service life of components. Low plasticity burnishing (LPB) is an advanced surface enhancement process providing a means of introducing compressive residual stresses into metallic components for enhanced fatigue, damage tolerance, and SCC performance. LPB processing can be applied as a repair process during scheduled overhauls or on new production components. High cycle fatigue tests were conducted on Type 410 stainless steel, a common alloy used in critical ST components, to compare the corrosion fatigue benefits of LPB to shot peening. Samples were tested in an active corrosion medium of 3.5% NaCl solution. Mechanical or accelerated corrosion damage was placed in test samples to simulate foreign object damage, pitting damage and water droplet erosion prior to testing. High cycle fatigue and residual stress results are shown. Compression from LPB was much deeper than the damage providing a nominal 100X improvement in fatigue life compared to the shallow compression from SP. Life extension from LPB offers significant O&M cost savings, improved reliability, and reduced outages for ST power generators.

On the application of the Kitagawa–Takahashi diagram to foreign-object damage and high-cycle fatigue

2002 ◽  
Vol 69 (13) ◽  
pp. 1425-1446 ◽  
Author(s):  
J.O Peters ◽  
B.L Boyce ◽  
X Chen ◽  
J.M McNaney ◽  
J.W Hutchinson ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Foreign Object Damage
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