scholarly journals Experimental and Numerical Study of Fatigue Damage Assessment under Combined High and Low Cycle Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Chaoshuai Han ◽  
Xianqiang Qu ◽  
Yongliang Ma ◽  
Dexin Shi
Keyword(s):  
Fatigue Life ◽  
Numerical Simulations ◽  
Fatigue Damage ◽  
Damage Assessment ◽  
Numerical Study ◽  
Engineering Application ◽  
Design Tool ◽  
Combined Loading ◽  
Type Specimens ◽  
Cycle Loading

This paper studies fatigue damage under combined high and low cycle loading. The interaction of two types of loading will greatly reduce fatigue life of structures. Existing methods usually neglect the minor high cycle loading, which obviously underestimates the total fatigue damage. To solve this problem, four methods are proposed and extended for the case of combined loading. Numerical simulations based on the superposition of two sine waves are performed. Experiments are carried out using “DH36” smooth round-type specimens. Damage predictions results by four methods are compared to the experimental results. It is concluded that some methods give satisfactory fatigue damage estimations and can be regarded as a safe design tool in engineering application.

scholarly journals Numerical Study on the Fatigue Limit of Metallic Glasses under Cyclic Tension-Compression Loading

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1732
Author(s):  
Jinfeng Yan ◽  
Wenjun Meng ◽  
Zhi Chen ◽  
Hong Guo ◽  
Xianguo Yan
Keyword(s):  
Fatigue Life ◽  
Metallic Glass ◽  
Fatigue Limit ◽  
Free Volume ◽  
Strain Amplitude ◽  
Numerical Study ◽  
Hydrostatic Stress ◽  
Shear Banding ◽  
Engineering Application ◽  
Free Volume Theory

Numerical study was performed to determine the fatigue limit of metallic glass under tension-compression cyclic loading. A revised free-volume theory which considers the hydrostatic stress was utilized to make the predictions. Systematical simulations showed that a higher strain amplitude is prone to making the sample completely damaged earlier. However, lower strain fluctuations could result in a longer fatigue life. Shear banding evolution history described by free-volume localization could reasonably explain the mechanical responses of different samples. In addition, compressive loading could give rise to a higher stress than that under tensile loading because of hydrostatic stress contribution. In the end, a correlation between fatigue life and applied strain amplitude was plotted which could supply a guidance for designing the engineering application of metallic glass under periodic loading.

scholarly journals Numerical Study on the Elastic Deformation and the Stress Field of Brittle Rocks under Harmonic Dynamic Load

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 851
Author(s):  
Siqi Li ◽  
Shenglei Tian ◽  
Wei Li ◽  
Xin Ling ◽  
Marcin Kapitaniak ◽  
...  
Keyword(s):  
Stress Field ◽  
Numerical Simulations ◽  
Elastic Deformation ◽  
Fatigue Damage ◽  
Dynamic Load ◽  
Static Load ◽  
Numerical Study ◽  
Rock Fracture ◽  
Dynamic Loads ◽  
Brittle Rocks

In order to study the deformation displacement and the stress field of brittle rocks under harmonic dynamic loading, a series of systematic numerical simulations are conducted in this paper. A 3D uniaxial compression simulation is carried out to calibrate and determine the property parameters of sandstone and a model of the cylindrical indenter intruding the rock is proposed to analyze the process of elastic deformation. Four main parameters are taken into account, namely the position on the rock, the frequency and the amplitude of dynamic load, the type of indenter and the loading conditions (static and static-dynamic). Based on the analysis undertaken, it can be concluded that both of the deformation displacement and stress field of the rock change in a harmonic manner under the static-dynamic loads. The frequency and the amplitude of harmonic dynamic load determine the period and the magnitude of the rock response, respectively. In addition, the existence of harmonic dynamic load can aggravate the fatigue damage of the rock and allow a reduction in static load. Our investigations confirm that the static-dynamic loads are more conducive to rock fracture than static load.

Fatigue Damage Assessment Correlating with I-Kaz Coefficient

2013 ◽  
Vol 471 ◽  
pp. 235-240
Author(s):  
Mahfodzah M. Padzi ◽  
S. Abdullah ◽  
Mohd Zaki Nuawi
Keyword(s):  
Fatigue Life ◽  
Carbon Steel ◽  
Fatigue Damage ◽  
Strain Gauge ◽  
Damage Assessment ◽  
Data Acquisition System ◽  
Sampling Frequency ◽  
Fatigue Tests ◽  
Constant Loading ◽  
Aisi 1045

This paper describes the correlation between fatigue life with the I-kaz coefficients. Fatigue tests were performed according to the ASTM E466-96 standard with a strain gauge attached to the specimen being tested. AISI 1045 carbon steel was used as the material for this test due to its wide applications in the automotive and machinery industry. Fatigue tests were carried out at several constant loading stresses of 610 MPa, 650 MPa and 690 MPa at the sampling frequency of 8 Hz. A set of data acquisition system was used to collect the fatigue strain signals. The integrated Kurtosis-based algorithm for Z-filter (I-kaz) technique had been used to find the I-kaz coefficient. The I-kaz coefficient is found to have a good correlation with fatigue life, other than can represent fatigue damage.

Probabilistic Modeling of Fatigue Damage Accumulation under Spectrum Loading

2014 ◽  
Vol 684 ◽  
pp. 169-175
Author(s):  
Xian Min Chen ◽  
Hong Na Dui
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Engineering Application ◽  
Al Alloy ◽  
Numerical Verification ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Fatigue Damage Accumulation ◽  
Spectrum Loading

A probabilistic methodology for modeling fatigue damage accumulation and fatigue life under variable amplitude loading is proposed in this paper. With probabilistic modifications, the calculative consistency between fatigue damage and life is achieved in the model and the load sequence effects are properly accounted for variable amplitude loading. This damage model overcomes the inherent deficiencies in the linear damage accumulation rule but still preserves its simplicity for engineering application. With Monte Carlo sampling method, numerical verification of this model is conducted under two-level spectrum loading. The predicted probabilistic distributions of fatigue life are validated by the fatigue tests on Al-alloy straight lugs.

Effect of Plastic Hardening Models on Fatigue Life Simulation of Pipeline Elbows Under Operating Pressure and Cyclic Bending

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Fatigue Life ◽  
Numerical Study ◽  
Kinematic Hardening ◽  
Combined Loading ◽  
Operating Pressure ◽  
Element Analysis ◽  
Hardening Model ◽  
Hardening Models ◽  
Plastic Hardening ◽  
Plane Bending

Abstract This paper presents a numerical study of plastic hardening models used in the stress, strain, and fatigue life simulations of a pipeline elbow under operating pressure and cyclic in-plane bending. To determine more accurate stresses, strains, and fatigue life of the elbow in cyclic loading, the material plastic hardening response and the Bauschinger effect need to be considered properly in the numerical simulation. The isotropic, kinematic, and combined isotropic/kinematic hardening models are, thus, evaluated in the elastic-plastic finite element analysis (FEA) of a benchmark beam. On this basis, those plastic hardening models are applied to simulate the elbow under combined loading of constant internal pressure and cyclic in-plane bending. With the FEA results and selected fatigue models that are commonly used in the pipeline industry, fatigue life of the elbow is predicted for each hardening model. As such, the appropriate plastic hardening model and fatigue life model to predict fatigue life of the elbow are determined.

scholarly journals Fatigue Damage Assessment for Concrete Structures Using a Frequency-Domain Method

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Hongyan Ding ◽  
Qi Zhu ◽  
Puyang Zhang
Keyword(s):  
Frequency Domain ◽  
Fatigue Damage ◽  
Time Domain ◽  
Damage Assessment ◽  
Numerical Study ◽  
Frequency Domain Method ◽  
Minor Effect ◽  
Domain Method ◽  
Frequency Domain Methods ◽  
The Time Domain

A fatigue damage assessment for concrete was carried out according to Eurocode 2. Three frequency-domain methods, the level crossing counting (LCC) method, the range counting (RC) method, and a new proposed method, were used for the damage assessment. The applicability of these frequency-domain methods was evaluated by comparison with the rainflow counting method in the time domain. A preliminary numerical study was carried out to verify the applicability of the frequency-domain methods for stress processes with different bandwidths; thus, the applicability of the LCC method and the new method was preliminarily confirmed. The fatigue strength of concrete had a minor effect on the fatigue damage assessment. The applicability of the LCC and the new methods deteriorated for relatively low coefficients of variance of the stress process because the ultimate number of constant amplitude cycles was sensitive to the range of the cycles. The validity of the joint probability functions of the two methods was proven using a numerical simulation. The integration intervals of the two frequency-domain methods were varied to estimate the lower and upper bounds on the fatigue damage, which can serve as references to evaluate the accuracy of the time-domain method results.

Using Ansys for Design and Numerical Study of a Specific Fixed Wing UAV

2018 ◽  
Vol 55 (4) ◽  
pp. 652-657 ◽  
Author(s):  
Gabriel Murariu ◽  
Razvan Adrian Mahu ◽  
Adrian Gabriel Murariu ◽  
Mihai Daniel Dragu ◽  
Lucian P. Georgescu ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Unmanned Aerial Vehicle ◽  
Numerical Study ◽  
Flight Time ◽  
Cluster System ◽  
Numerical Results ◽  
Operational Performance ◽  
Gliding Flight ◽  
Aerial Vehicle ◽  
Constant Altitude

This article presents the design of a specific unmanned aerial vehicle UAV prototype own building. Our UAV is a flying wing type and is able to take off with a little boost. This system happily combines some major advantages taken from planes namely the ability to fly horizontal, at a constant altitude and of course, the great advantage of a long flight-time. The aerodynamic models presented in this paper are optimized to improve the operational performance of this aerial vehicle, especially in terms of stability and the possibility of a long gliding flight-time. Both aspects are very important for the increasing of the goals� efficiency and for the getting work jobs. The presented simulations were obtained using ANSYS 13 installed on our university� cluster system. In a next step the numerical results will be compared with those during experimental flights. This paper presents the main results obtained from numerical simulations and the obtained magnitudes of the main flight coefficients.

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.

scholarly journals Investigation of Changes in Fatigue Damage Caused by Mean Load under Block Loading Conditions

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2738
Author(s):  
Roland Pawliczek ◽  
Tadeusz Lagoda
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Strain Curve ◽  
Mean Value ◽  
Fatigue Properties ◽  
Stress Strain ◽  
Reference Case ◽  
Block Loading ◽  
The Mean ◽  
Mean Strain

The literature in the area of material fatigue indicates that the fatigue properties may change with the number of cycles. Researchers recommend taking this into account in fatigue life calculation algorithms. The results of simulation research presented in this paper relate to an algorithm for estimating the fatigue life of specimens subjected to block loading with a nonzero mean value. The problem of block loads using a novel calculation model is presented in this paper. The model takes into account the change in stress–strain curve parameters caused by mean strain. Simulation tests were performed for generated triangular waveforms of strains, where load blocks with changed mean strain values were applied. During the analysis, the degree of fatigue damage was compared. The results of calculations obtained for standard values of stress–strain parameters (for symmetric loads) and those determined, taking into account changes in the curve parameters, are compared and presented in this paper. It is shown that by neglecting the effect of the mean strain value on the K′ and n′ parameters and by considering only the parameters of the cyclic deformation curve for εm = 0 (symmetric loads), the ratio of the total degree of fatigue damage varies from 10% for εa = 0.2% to 3.5% for εa = 0.6%. The largest differences in the calculation for ratios of the partial degrees of fatigue damage were observed in relation to the reference case for the sequence of block n3, where εm = 0.4%. The simulation results show that higher mean strains change the properties of the material, and in such cases, it is necessary to take into account the influence of the mean value on the material response under block loads.

scholarly journals Design and analysis of concrete-filled tubular flange girders under combined loading

2021 ◽  
pp. 136943322110015
Author(s):  
Rana Al-Dujele ◽  
Katherine Ann Cashell
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Failure Modes ◽  
Numerical Study ◽  
Combined Loading ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Combined Effects ◽  
Element Analysis ◽  
Hollow Section

This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

Sign in / Sign up

Export Citation Format

Share Document