Low-Cycle Fatigue Performance of Buckling Restrained Braces and Assessment of Cumulative Damage under Severe Earthquakes

2018 ◽  
Vol 763 ◽  
pp. 867-874
Author(s):  
Yu Shu Liu ◽  
Ke Peng Chen ◽  
Guo Qiang Li ◽  
Fei Fei Sun
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Structural Reliability ◽  
Low Cycle Fatigue ◽  
Engineering Application ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Variable Amplitude ◽  
Buckling Restrained Braces ◽  
Energy Dissipation Devices

Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.

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.

Factors Affecting the Low Cycle Fatigue Behavior around the Weak Axis of Welded I-Section Bracing Members

2006 ◽  
Vol 324-325 ◽  
pp. 959-962
Author(s):  
Yao Chun Zhang ◽  
Wei An Lian ◽  
Wen Yuan Zhang
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Crack Initiation ◽  
Surface Crack ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Loading History ◽  
Energy Dissipation Capacity ◽  
Surface Crack Initiation

The low cycle fatigue behavior and energy dissipation capacity around the weak axis of the welded I-section bracing members are investigated by 35 pinned-pinned bracing specimen tests under the axial cyclic loading with different characteristics. Particular attention is paid to the effects of loading amplitude, loading history and geometry properties of these members. It is found that the fatigue damage propagating to fracture in the flanges of the bracing members can be divided into 3 stages involving the macroscopic surface crack initiation, the penetrated crack formation and the penetrated crack propagation. Some empirical formulas to estimate the fatigue life and cyclic energy dissipation capacity of the bracing members are also presented based on the experimental data. The statistical analysis indicates that the fatigue life to surface crack initiation significantly depends on the inelastic local buckling and will increase with decreasing width-thickness ratio of the flanges and increasing slenderness ratios of the bracing members. Besides, it is found that the low cycle fatigue and energy dissipation of these members also depends on loading amplitude and loading history, and the effects of overloads and mean compression amplitude can improve the fatigue performance of bracing members. The test results show that the bracing members with better low-cycle fatigue resistance have the better energy dissipation capacities.

The Role of Surface Topography on Fatigue Behaviour of Nickel Based Superalloys

2014 ◽  
Vol 891-892 ◽  
pp. 48-53 ◽  
Author(s):  
Dennise Tanoko Ardi ◽  
Yue Gang Li ◽  
Kelvin Hau Kong Chan ◽  
Liam Blunt ◽  
M.R. Bache
Keyword(s):  
Fatigue Life ◽  
Surface Topography ◽  
Low Cycle Fatigue ◽  
Three Dimensional ◽  
Fatigue Behaviour ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Nickel Based Superalloy ◽  
Topographic Parameters

Advanced areal (three-dimensional) characterisation of surface topography was applied to laboratory scale fatigue test specimens manufactured from the nickel based superalloy Alloy720Li. Finishing was deliberately manipulated to offer four distinct grades of topography. Subsequent low cycle fatigue performance was then correlated to a range of parameters selected to represent the surface topography. The aim of the ongoing study is to predict fatigue performance and aid to establish correlations between topographic parameters and fatigue life.

Low-cycle fatigue life evaluation of buckling-restrained braces based on cumulative plastic deformation curves

2021 ◽  
pp. 136943322110499
Author(s):  
Chao Tong ◽  
Jing Wu ◽  
Kun Hua ◽  
Huiwen Tian
Keyword(s):  
Fatigue Life ◽  
Strain Amplitude ◽  
Evaluation Method ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Loading History ◽  
Limit Values ◽  
Deformation Curves ◽  
Buckling Restrained Braces ◽  
Multiple Earthquakes

To quantitatively evaluate the low-cycle fatigue life of buckling-restrained braces (BRBs), an evaluation method for BRBs based on the combination of the CPD curves and CPD measurement meter (CMM) is established herein. The difference between two CPD curves (i.e., the CPD curves under constant strain amplitude loading history (C-CPD) and under random strain amplitude loading history (R-CPD)), and their selection criteria to evaluate the low-cycle fatigue life of BRBs are discussed. An example under the variable strain amplitude (VSA) loading history and an example under the multiple earthquakes are carried out. Finally, the CPD limit values of BRBs in the ANSI/AISC 341-10 and FEMA-450 are discussed by statistical analysis of the test results of BRBs. The analysis results show that the C-CPD curve can be used to evaluate the low-cycle fatigue life of BRBs under the VSA loading, and the R-CPD curve can be used to evaluate the low-cycle fatigue life of BRBs under the multiple earthquakes. The degree of reliability of the current CPD limit value is not enough. A CPD limit curve is recommended in this study to quantify the low-cycle fatigue performance of BRBs.

scholarly journals Research on the Fatigue Performance of TC6 Compressor Blade under the CCF Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Zhang Yakui ◽  
Guo Shuxiang
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Compressor Blade ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Test Rig ◽  
Source Characteristics ◽  
Fracture Appearance ◽  
Fatigue Life Reduction

This paper studied the influence of high and low combined fatigue (CCF) on compressor blade fatigue performance. We investigated the coupling between low cycle fatigue (LCF) loading from centrifugal force with high cycle fatigue (HCF) loading from vibration and determined the blade disc vibration frequency using static analysis at maximum rotational speed. We designed and constructed a combined fatigue test rig, and CCF tests were performed on a TC6 compressor blade to analyze fatigue life characteristics. Results showed that CCF could significantly shorten blade life compared with pure LCF and that larger HCF caused more significant fatigue life reduction. Fatigue source characteristics and CCF fracture appearance were observed and analyzed using a scanning electron microscope (SEM).

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