Multi-Axial Fatigue Life Model Evaluation and Life Prediction for Turbine Disk

2011 ◽  
Vol 130-134 ◽  
pp. 2330-2334
Author(s):  
Jun Hong Zhang ◽  
Feng Lv ◽  
Wen Peng Ma
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Turbine Disk ◽  
Strain History ◽  
Cycle Fatigue ◽  
Critical Plane ◽  
Element Analysis ◽  
Critical Plane Approach ◽  
Axial Fatigue

Multi-axial low cycle fatigue was the main failure mode of turbine disk. Critical plane approach was an idea method for the prediction of multi-axial fatigue life. A lot of models based on critical plane approach have been put forward, but there is not a universal prediction model. In order to find a model for turbine disk, linear heteroscedastic regression analysis of the standard low cycle fatigue data was carried out to obtained fatigue parameters. After verifying the accuracy of the finite element model, the stress and strain history of the danger point was obtained based on elastic-plastic finite element analysis. The critical plane and the damage of it was found by the method of coordinate transformation. The fatigue life of turbine disk was estimated by different models, and the results were quite different. SWT-Bannantine model was more suitable for the turbine disk.

scholarly journals Fatigue Analysis of NiTi Rotary Endodontic Files through Finite Element Simulation: Effect of Root Canal Geometry on Fatigue Life

2021 ◽  
Vol 10 (23) ◽  
pp. 5692
Author(s):  
Victor Roda-Casanova ◽  
Antonio Pérez-González ◽  
Álvaro Zubizarreta-Macho ◽  
Vicente Faus-Matoses
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Root Canal ◽  
Numerical Procedure ◽  
Element Model ◽  
Radius Of Curvature ◽  
Critical Plane ◽  
Element Analysis ◽  
Element Simulation ◽  
Critical Plane Approach

This article describes a numerical procedure for estimating the fatigue life of NiTi endodontic rotary files. An enhanced finite element model reproducing the interaction of the endodontic file rotating inside the root canal was developed, which includes important phenomena that allowed increasing the degree of realism of the simulation. A method based on the critical plane approach was proposed for extracting significant strain results from finite element analysis, which were used in combination with the Coffin–Manson relation to predict the fatigue life of the NiTi rotary files. The proposed procedure is illustrated with several numerical examples in which different combinations of endodontic rotary files and root canal geometries were investigated. By using these analyses, the effect of the radius of curvature and the angle of curvature of the root canal on the fatigue life of the rotary files was analysed. The results confirm the significant influence of the root canal geometry on the fatigue life of the NiTi rotary files and reveal the higher importance of the radius of curvature with respect to the angle of curvature of the root canal.

A weight function method for multiaxial low-cycle fatigue life prediction under variable amplitude loading

2018 ◽  
Vol 53 (4) ◽  
pp. 197-209 ◽  
Author(s):  
Xiao-Wei Wang ◽  
De-Guang Shang ◽  
Yu-Juan Sun
Keyword(s):  
Fatigue Life ◽  
Weight Function ◽  
Life Prediction ◽  
Function Method ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Critical Plane ◽  
Variable Amplitude ◽  
Weight Function Method

A weight function method based on strain parameters is proposed to determine the critical plane in low-cycle fatigue region under both constant and variable amplitude tension–torsion loadings. The critical plane is defined by the weighted mean maximum absolute shear strain plane. Combined with the critical plane determined by the proposed method, strain-based fatigue life prediction models and Wang-Brown’s multiaxial cycle counting method are employed to predict the fatigue life. The experimental critical plane orientation and fatigue life data under constant and variable amplitude tension–torsion loadings are used to verify the proposed method. The results show that the proposed method is appropriate to determine the critical plane under both constant and variable amplitude loadings.

Outline of the Recent Consolidated Revision of EN13445-3, Clause 18 and Related Annexes: Detailed Assessment of Fatigue Life

2019 ◽  
Author(s):  
Jürgen Rudolph ◽  
Guy Baylac ◽  
Ralf Trieglaff ◽  
Rüdiger Gawlick ◽  
Michael Krämer ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Assessment Method ◽  
Structural Stress ◽  
Critical Plane ◽  
Fatigue Assessment ◽  
European Working ◽  
Critical Plane Approach ◽  
Detailed Assessment

Abstract The European Pressure Vessel Standard EN 13445 (harmonized Standard acc. to PED 2014/68/EU) provides in its Part 3 (Design) a simplified method for fatigue assessment (Clause 17) and a detailed method of fatigue assessment (Clause 18). While the new revision of Clause 17 has already been adopted, Clause 18 “Detailed Assessment of Fatigue Life” is now available as a consolidated revision in inquiry phase. This major and comprehensive revision has been developed within the framework of the European working group CEN/TC 54/WG 53 – Design methods and constitutes a crucial step towards a modern and user-friendly engineering fatigue assessment method. The overall structure and amendments of Clause 18 are to be presented. All these amendments aim at a significant increase in user friendliness and clear guidelines for application. The following items are to be mentioned in that context: • Fatigue assessment of welded components based on structural stress and structural hot-spot stress approaches, • Detailed guidelines for determining relevant stresses and stress ranges, • Cycle counting proposals in the context of the fatigue assessment method including a critical plane approach. The fatigue assessment of welded components is separated from the fatigue assessment of un-welded parts as it has already been done in previous versions with respective methodological differences. Stress analyses for clause 18 are usually based on detailed finite element analyses (FEA). As an essential amendment for the user, the determination of structural stress ranges for the fatigue assessment of welds is further detailed in a new appropriate annex. Different applicable methods for the determination of structural stresses are explained in connection with the requirements of the finite element models and analyses. The cycle counting issue is comprehensively treated in the context of different design and operation situations (design transients, operational stress-time-histories). The description is detailed towards a critical plane approach. Detailed proposals for implementation in an algorithmic programming framework are given making the described methods ready to use.

Low Cycle Fatigue Tests and Simulations on Steel Elbows

2013 ◽  
Author(s):  
Patricia Pappa ◽  
George E. Varelis ◽  
Spyros A. Karamanos ◽  
Arnold M. Gresnigt
Keyword(s):  
Finite Element ◽  
Low Cycle Fatigue ◽  
Local Strain ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Out Of Plane ◽  
Strain Gauge Measurements ◽  
Number Of Cycles

In this paper the low cycle fatigue behaviour of steel elbows under strong cyclic loading conditions (in-plane and out-of-plane) is examined. The investigation is conducted through advanced finite element analysis tools, supported by real-scale test data for in-plane bending. The numerical results are successfully compared with the experimental measurements. In addition, a parametric study is conducted, which is aimed at investigating the effects of the diameter-to-thickness ratio on the low-cycle fatigue of elbows, focusing on the stress and strain variations. Strain gauge measurements are compared with finite element models. Upon calculation of local strain variation at the critical location, the number of cycles to fracture can be estimated.

scholarly journals Low Cycle Fatigue Failure of a Sitka Spruce Tree in Hurricane Winds

2014 ◽  
Vol 40 (5) ◽  
Author(s):  
Warren Leigh
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Wind Speed ◽  
Fatigue Failure ◽  
Low Cycle Fatigue ◽  
Failure Prediction ◽  
Picea Sitchensis ◽  
Cycle Fatigue ◽  
Hurricane Wind ◽  
The Impact

Pine plantations are prone to stem breakage due to high cyclic stress levels associated with hurricane force winds. Stress analytical and finite element simulation models were constructed of a representative profile of a (Sitka) Picea sitchensis tree. The profile surface stress (S) was determined due to the combined load of tree self-weight and hurricane wind speed. The results were complemented by reference to two other studies by other researchers that investigated the impact of fatigue cycles on failure (N) of pine wood and tree sway cycles to present a stem fatigue life prediction. The position of maximum surface profile stress and trunk fracture initiation location was ascertained from a non-uniform stress response. No stress uniformity along the trunk profile was observed for any wind-load case examined. The analytical model and finite element analysis of the P. sitchensis tree trunk profile revealed a statically adequate strength reserve factor of 1.4, which suggested another mode of failure was responsible. Fatigue life failure prediction was examined under cyclic and same-stress amplitude related to the hurricane wind speed of 33 m s-1. Predicted trunk fracture occurred in 2.6 hours, which dramatically reduced to two minutes with an increase in wind speed of only 1 m s-1. The calculated exposure time was similar to that recorded during Hurricane Hugo’s transit in 1989. The time-to-failure prediction obtained by the method of analysis provided in this study seemed plausible, and that the profile associated with the P. sitchensis tree would suffer trunk breakage by low cycle fatigue failure.

Sign in / Sign up

Export Citation Format

Share Document