Selection of multiaxial fatigue damage model based on the dominated loading modes

2011 ◽  
Vol 33 (5) ◽  
pp. 735-739 ◽  
Author(s):  
Hong Chen ◽  
De-Guang Shang ◽  
Ming Bao
Keyword(s):  
Fatigue Damage ◽  
Damage Model ◽  
Multiaxial Fatigue ◽  
Model Based ◽  
Loading Modes ◽  
Selection Of

scholarly journals Extremely-Low-Cycle Fatigue Damage for Beam-to-Column Welded Joints Using Structural Details

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1768
Author(s):  
Lizhen Huang ◽  
Weilian Qu ◽  
Ernian Zhao
Keyword(s):  
Fatigue Damage ◽  
Welded Joints ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Multiaxial Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Butt Weld ◽  
Damage Models ◽  
Structural Details

The multiaxial fatigue critical plane method can be used to evaluate the extremely-low-cycle fatigue (ELCF) damage of beam-to-column welded joints in steel frameworks subjected to strong seismic activity. In this paper, fatigue damage models using structural detail parameters are studied. Firstly, the fatigue properties obtained from experiments are adopted to assess ELCF life for steel frameworks. In these experiments, two types of welded specimens, namely, plate butt weld (PB) and cruciform load-carrying groove weld (CLG), are designed according to the structural details of steel beam and box column joints, in which both structural details and welded factors are taken into account. Secondly, experiments are performed on three full-scale steel welded beam-to-column joints to determine the contribution of stress and/or strain to damage parameters. Finally, we introduce a modification of the most popular fatigue damage model of Fatemi and Socie (FS), modified by us in a previous study, for damage evaluation, and compare this with Shang and Wang (SW) in order to examine the applicability of the fatigue properties of PB and CLG. This study shows that the modified FS model using the fatigue properties of CLG can predict the crack initiation life and evaluate the damage of beam-to-column welded joints, and can be subsequently used for further investigation of the damage evolution law.

Advanced Models for Fatigue Life Estimation of Combustor Components for Gas Turbine Application

2019 ◽  
Author(s):  
Dileep Sivarama Iyer ◽  
Nikhil Chandran Pillai
Keyword(s):  
Fatigue Life ◽  
Gas Turbine ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Multiaxial Fatigue ◽  
Universal Method ◽  
Cycle Fatigue ◽  
Operating Cycle ◽  
Experimental Values

Abstract Modern day combustors operate at very high temperatures which are close to combustor material softening temperatures. At the same time, to meet stringent emission legislations there is a strong drive to improve upon the rich burn combustor technology or shift to advanced lean burn combustor technologies. One of the key driver to improve emission is to save the cooling air budget and use the saved air for primary combustion but this approach would require more advanced and efficient cooling techniques. Fan shaped effusion cooling technology is a very promising technique as it offers high film cooling effectiveness. However, complex cooling features associated with this technology can lead to higher stress concertation and localized triaxial stress state. This stressstrain field in combination with a typical gas turbine engine operating cycle makes such effusion holes highly vulnerable to the thermo-mechanical fatigue failure. Hence to ensure the safety and reliability of combustor liners with such innovative features, it is essential to have thorough understanding of the stress-strain field in the vicinity and accurate prediction of life to first crack. The biggest challenge the designers and engineers face while predicting the initiation life of a structure is selecting the appropriate fatigue damage model for an application. This is due to following reasons: (a) The scatter in fatigue life predicted using different models and experimental values are very huge (b) There is no general universal method which can predict the multiaxial fatigue life accurately for all the materials and loading conditions (c) No general consensus exits among the researchers on which model have to be used for a particular application, material, loading and geometry (d) Application level studies are seldom available on this subject, most of the studies are restricted to laboratory level specimens with very limited implications to industry. Ideally, the fatigue damage model which has to be used for a particular application has to be validated through experiments. To meet this objective, several test specimens featuring novel fan shaped hole geometries were mass-produced using state of the art laser drilling technology. All these specimens were subjected to strain controlled isothermal low cycle fatigue test and the cycles to crack initiation was monitored using potential drop method. Six different multiaxial fatigue damage models (which can be used in low cycle fatigue regime) viz. Walker model, Smith Watson and Topper model (SWT), Fatemi Socie model (FS), Wang and Brown model (WB), Shang model (SW) and Xu model were selected and the life estimated by these models were compared with the experimental values. From the study it is observed that Xu model in which the damage parameter is built using the concept of shear strain energy looks most promising for this application.

scholarly journals Interaction Between Normal and Shear Stresses and Its Effect on Multiaxial Fatigue Behavior

2019 ◽  
Vol 300 ◽  
pp. 16007 ◽  
Author(s):  
Shahriar Sharifimehr ◽  
Ali Fatemi
Keyword(s):  
Normal Stress ◽  
Fatigue Damage ◽  
Shear Failure ◽  
Fatigue Behavior ◽  
Damage Model ◽  
Multiaxial Fatigue ◽  
Experimental Program ◽  
Shear Stresses ◽  
Critical Plane ◽  
Normal And Shear Stresses

Interaction between normal and shear stresses plays an important role in multiaxial fatigue damage. The aim of this study was to investigate this interaction effect on fatigue behavior of shear failure mode materials under multiaxial loading conditions. In order to model the influence of normal stress on fatigue damage, the present study introduces a method based on the idea that the normal stress acting on the critical plane orientation causes two types of influence, first by affecting roughness induced closure, and second, by a fluctuating normal stress affecting the growth of small cracks in mode II. The summation of these terms could then be used in shear-based critical plane damage models, for example FS damage model, which use normal stress as a secondary input. In order to investigate the effect of the method, constant amplitude load paths with different levels of interaction between the normal and shear stresses were designed for an experimental program. The proposed method was observed to result in improved fatigue life estimations where significant interactions between normal and shear stresses exist.

Sign in / Sign up

Export Citation Format

Share Document