Influence of non-metallic inclusions on the high cycle fatigue strength of steels

2022 ◽  
Vol 154 ◽  
pp. 106553
Author(s):  
Sabrina Vantadori ◽  
Camilla Ronchei ◽  
Daniela Scorza ◽  
Andrea Zanichelli ◽  
Lucas Carneiro Araújo ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Cycle Fatigue ◽  
Metallic Inclusions

Assessment of Fatigue Reliability of Power Transmission Gearing for Aerospace Propulsion Applications

2013 ◽  
Author(s):  
Stefano Beretta ◽  
Mauro Filippini ◽  
Pietro Luccarelli ◽  
Andrea Motta ◽  
Giuseppe Pasquero
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Crack Growth ◽  
High Cycle Fatigue ◽  
Power Transmission ◽  
High Strength ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Metallic Inclusions

The fatigue strength in presence of inclusions is one of the main topics for the fatigue of high strength steels, especially the case hardened ones adopted for power transmission. In this paper we analyze the fatigue strength of carburized gears in presence of inclusions in order to develop the reliability assessment of a power transmission for aerospace propulsion. The high cycle fatigue properties of a high strength carburizing steel have been experimentally determined by conducting bending fatigue tests with specimens with artificial defects and a coherent model for the assessment of fatigue crack growth thresholds by taking into account of the residual stresses due to carburizing has been developed. In parallel, the distribution of non-metallic inclusions has been estimated by carrying out high cycle fatigue tests onto cylindrical smooth specimens and by inspection of mirror polished sections of the material. Eventually, by employing a simplified finite element model of a highly loaded gear wheel, the bending fatigue strength of gear teeth and the reliability of a turbo-propeller power transmission was determined by incorporating the fatigue crack growth thresholds, the measured residual stress profiles and the statistics of extreme non-metallic inclusions into a competing risks model applied to FE discretization.

scholarly journals On the determination of the bending fatigue strength in and above the very high cycle fatigue regime of shot-peened gears

2021 ◽  
Author(s):  
D. Fuchs ◽  
S. Schurer ◽  
T. Tobie ◽  
K. Stahl
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Load Carrying Capacity ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Very High Cycle Fatigue ◽  
Bending Load ◽  
Load Carrying ◽  
Bending Fatigue Strength ◽  
Very High

AbstractDemands on modern gearboxes are constantly increasing, for example to comply with lightweight design goals or new CO2 thresholds. Normally, to increase performance requires making gearboxes and powertrains more robust. However, this increases the weight of a standard gearbox. The two trends therefore seem contradictory. To satisfy both of these goals, gears in gearboxes can be shot-peened to introduce high compressive residual stresses and improve their bending fatigue strength. To determine a gear’s tooth root bending fatigue strength, experiments are conducted up to a defined number of load cycles in the high cycle fatigue range. However, investigations of shot-peened gears have revealed tooth root fracture damage initiated at non-metallic inclusions in and above the very high cycle fatigue range. This means that a further reduction in bending load carrying capacity has to be expected at higher load cycles, something which is not covered under current standard testing conditions. The question is whether there is a significant decrease in the bending load carrying capacity and, also, if pulsating tests conducted at higher load cycles—or even tests on the FZG back-to-back test rig—are necessary to determine a proper endurance fatigue limit for shot-peened gears. This paper examines these questions.

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 High-cycle fatigue strength of a pultruded composite material

2009 ◽  
Vol 3 (7) ◽  
pp. 65-72
Author(s):  
C. Colombo ◽  
M. Guagliano ◽  
L. Vergani
Keyword(s):  
Composite Material ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Cycle Fatigue

High Cycle Fatigue Strength of Spring Steel with Small Scratches

2017 ◽  
pp. 541-548 ◽  
Author(s):  
Yoshiro Nishimura ◽  
Masahiro Endo ◽  
Keiji Yanase ◽  
Yuichi Ikeda ◽  
Susumu Miyakawa ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Spring Steel ◽  
Cycle Fatigue
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