scholarly journals High cycle fatigue assessment of steel load-carrying cruciform welded joints: an overview of recent results

2018 ◽  
Vol 12 (46) ◽  
pp. 94-101
Author(s):  
song wei ◽  
Xuesong Liu
Keyword(s):  
Welded Joints ◽  
High Cycle Fatigue ◽  
Cycle Fatigue ◽  
Fatigue Assessment ◽  
Load Carrying

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.

A Novel High Cycle Fatigue Assessment of Small-Bore Side Branches: Tailor-Made Acceptable Vibration Levels Based on the Remaining Life of Existing Structures

2014 ◽  
Author(s):  
Pieter van Beek ◽  
Richard Pijpers ◽  
Kenneth Macdonald ◽  
Johan Maljaars ◽  
Knud Lunde ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
High Cycle Fatigue ◽  
Side Branch ◽  
International Standards ◽  
Screening Methods ◽  
Piping System ◽  
Cycle Fatigue ◽  
Fatigue Assessment ◽  
Mechanics Model

In the process systems of offshore installations, welded small-bore side branches can prove vulnerable to high-cycle fatigue failure due to vibrations. This is especially the case for welded connections at tie-in points to the main pipe which are often critical details. International standards and guidelines therefore provide maximum acceptable vibration levels to ensure long term safe operation. In some guidelines, however, these acceptable vibration levels are phrased in terms of screening levels and in practice can be unduly conservative. Process pipework might then unjustly be regarded as unsafe based on measured vibrations in the field. This is especially true for offshore systems, which are characterized by low mechanical damping in the structure. This may result in overdesigned piping or over-conservative operational limits in order to keep vibration levels within the acceptable range. Furthermore, the screening methods and any detailed fatigue assessments typically use established stress-life (S-N) based fatigue design methods where uncertainty exists in the very high-cycle regime. This paper describes a novel and advanced tailor-made fatigue assessment method whereby acceptable vibration levels are based on maximum acceptable stress ranges for individual side branches. The acceptable stress ranges for each critical welded connection are based on a fracture mechanics analysis of fatigue crack growth. This method also minimizes the cantilevered (overhung) mass of small-bore side branches, whilst remaining safe for long-term operation. To illustrate the strength of the assessment methodology in practice, this paper describes the application of the procedure to a 2″ side branch connected to a main piping system. A fracture mechanics model and a detailed 3D finite element model are made. By comparing the stress ranges from the fracture mechanics model with the normalized stress ranges obtained from the dynamic FE analysis, maximum acceptable vibration levels for this particular side branch have been derived. The method is validated with experimental modal analysis and strain gauge measurements.

High cycle fatigue of welded joints with aging influence

2013 ◽  
Vol 45 ◽  
pp. 190-197 ◽  
Author(s):  
H. Zaletelj ◽  
V. Haesen ◽  
L. Dedene ◽  
G. Fajdiga ◽  
M. Nagode
Keyword(s):  
Welded Joints ◽  
High Cycle Fatigue ◽  
Cycle Fatigue

scholarly journals EXTREMELY LOW CYCLE FATIGUE ASSESSMENT FOR WELDED JOINTS BASED ON PEAK STRAIN APPROACH

2006 ◽  
Vol 62 (1) ◽  
pp. 101-109
Author(s):  
Takeshi HANJI ◽  
Kazuo TATEISHI ◽  
Kuniaki MINAMI ◽  
Kazuya KITOH
Keyword(s):  
Welded Joints ◽  
Low Cycle Fatigue ◽  
Peak Strain ◽  
Cycle Fatigue ◽  
Fatigue Assessment
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