Use of Fatigue Fuses for Prediction of Fatigue Life of Steel Bridges

1996 ◽  
Vol 1544 (1) ◽  
pp. 71-78
Author(s):  
Everett McEwen ◽  
George Tsiatas
Keyword(s):  
Fatigue Life ◽  
Highway Bridges ◽  
Fatigue Loading ◽  
Highway Bridge ◽  
Constant Amplitude ◽  
Bridge Inspection ◽  
Structural Details ◽  
Critical Issues ◽  
The Mean ◽  
Cycles To Failure

The fatigue fuse is a device for predicting the fatigue life of steel highway bridge members when the bridge is subject to variable loads. The fuse is calibrated so that the cracking of each of its four legs can be related to damage in the structure. In a preliminary laboratory study, fatigue fuses are attached to eight steel girders, selected to represent three types of structural details found in existing highway bridges. The fuses are cemented to the girders and the girders subjected to a constant-amplitude fatigue loading. Cracking of the fatigue fuses is monitored by checking electrical continuity across each fuse leg. Tests are continued until girder failure or until all fuse legs are broken and the mean fatigue life of the girder as predicted by AASHTO is reached. The breaking of the fuse legs is used to predict the fatigue life of each girder, which is then compared with the actual cycles to failure of the girder and the AASHTO mean life. The prediction gives satisfactory agreement with the AASHTO mean life in four of the tests. In two tests, the predictions vary significantly from the AASHTO mean life. Although several critical issues remain (such as adapting the fatigue fuse to the environment of a real bridge and conducting tests on a statistically valid sample), the results of this feasibility study indicate that the fuse could be a valuable tool for highway bridge inspection.

scholarly journals A study on fatigue life of RC bridge and its improvement methods

2018 ◽  
Vol 7 (4.5) ◽  
pp. 722
Author(s):  
Neha B ◽  
Sruthy S ◽  
Rahul T.M
Keyword(s):  
Fatigue Life ◽  
Highway Bridges ◽  
Highway Bridge ◽  
Traffic Data ◽  
Traffic Loads ◽  
Structural Details ◽  
Externally Bonded ◽  
Codal Provisions ◽  
Total Life ◽  
Ansys Workbench

Fatigue is a crucial factor which affects the total life and serviceability of highway bridges. There are several factors that contribute to the development of fatigue in RC bridges. Among them, traffic loads, wind loads and corrosion of reinforcement are some of the important factors to name a few. In order to address these fatigue issues and improve the fatigue life of highway bridges, many improvement meth- ods have been suggested in the literature. This study attempts to investigate the effectiveness of various improvement methods suggested in the literature. The improvement methods that has been included in this study are externally bonded reinforcement and deck overlay. To accomplish the objective, an existing highway bridge was selected based on the structural details and traffic data and then various improvement methods were applied to analyze its improvement in fatigue life. For analysis, an embedded reinforcement modeling was carried out in ANSYS followed by a nonlinear analysis in ANSYS workbench. The results of the study were found to be in alignment with AASTHO LRFD (2007), IRC SP 60(2002), IRC 6 (2014), IRC SP 37 (2010) and IRC 37 (2012) codal provisions. 

scholarly journals A Cyclic-Plasticity-Based Mechanistic Approach for Fatigue Evaluation of 316 Stainless Steel Under Arbitrary Loading

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Bipul Barua ◽  
Subhasish Mohanty ◽  
Joseph T. Listwan ◽  
Saurindranath Majumdar ◽  
Krishnamurti Natesan
Keyword(s):  
Fatigue Life ◽  
Fatigue Loading ◽  
Material Model ◽  
Cyclic Plasticity ◽  
Constant Amplitude ◽  
Stress Strain ◽  
Strain Evolution ◽  
Time Cycle ◽  
Fatigue Evaluation ◽  
Cyclic Plasticity Model

In this paper, a cyclic-plasticity-based fully mechanistic fatigue modeling approach is presented. This is based on time-dependent stress–strain evolution of the material over the entire fatigue life rather than just based on the end of live information typically used for empirical S∼N curve-based fatigue evaluation approaches. Previously, we presented constant amplitude fatigue test based related material models for 316 stainless steel (SS) base, 508 low alloy steel base, and 316 SS-316 SS weld which are used in nuclear reactor components such as pressure vessels, nozzles, and surge line pipes. However, we found that constant amplitude fatigue data-based models have limitation in capturing the stress–strain evolution under arbitrary fatigue loading. To address the aforementioned limitation, in this paper, we present a more advanced approach that can be used for modeling the cyclic stress–strain evolution and fatigue life not only under constant amplitude but also under any arbitrary (random/variable) fatigue loading. The related material model and analytical model results are presented for 316 SS base metal. Two methodologies (either based on time/cycle or based on accumulated plastic strain energy (APSE)) to track the material parameters at a given time/cycle are discussed and associated analytical model results are presented. From the material model and analytical cyclic plasticity model results, it is found that the proposed cyclic plasticity model can predict all the important stages of material behavior during the entire fatigue life of the specimens with more than 90% accuracy.

scholarly journals Fatigue Performance of Natural and Synthetic Rattan Strips Subjected to Cyclic Tensile Loading

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 76
Author(s):  
Yanting Gu ◽  
Jilei Zhang
Keyword(s):  
Tensile Strength ◽  
Fatigue Life ◽  
Ultimate Tensile Strength ◽  
Applied Stress ◽  
Stress Level ◽  
Tensile Loading ◽  
Constant Amplitude ◽  
Tensile Fatigue ◽  
Number Of Cycles ◽  
Cycles To Failure

Tensile fatigue performances of selected natural rattan strips (NRSs) and synthetic rattan strips (SRSs) were evaluated by subjecting them to zero-to-maximum constant amplitude cyclic tensile loading. Experimental results indicated that a fatigue life of 25,000 cycles began at the stress level of 50% of rattan material ultimate tensile strength (UTS) value for NRSs evaluated. Rattan core strips’ fatigue life of 100,000 cycles started at the stress level of 30% of its UTS value. Rattan bast strips could start a fatigue life of 100,000 cycles at a stress level below 30% of material UTS value. SRSs didn’t reach the fatigue life of 25,000 cycles until the applied stress level reduced to 40% of material UTS value and reached the fatigue life of 100,000 cycles at the stress level of 40% of material UTS value. It was found that NRSs’ S-N curves (applied nominal stress versus log number of cycles to failure) could be approximated by S=σou(1−H×log10⋅Nf). The constant H values in the equation were 0.10 and 0.08 for bast and core materials, respectively.

Corrosion Prevention Compound on the Fatigue Life of 2024-T3 Aluminum Alloy

Materials ◽  
2005 ◽  
Author(s):  
M. A. Wahab ◽  
J. H. Park ◽  
S. S. Pang
Keyword(s):  
Aluminum Alloy ◽  
Water Vapor ◽  
Fatigue Life ◽  
Crack Growth ◽  
Fatigue Loading ◽  
Corrosive Environment ◽  
Constant Amplitude ◽  
Corrosion Prevention ◽  
Electron Microscopic ◽  
Stress Ratios

Corrosion-Prevention-Compounds (CPC) are commonly used to prevent corrosion in the aircraft industry. The presence of corrosive environment on aircraft structures has detrimental effects on the aircraft components which reduces the fatigue life and may also accelerate the crack growth rate in the structures. This is an experimental study on 2024-T3 aluminum alloy to investigate the effect of fatigue crack growth (life from threshold crack growth to final failure) using CPC on fatigue life. The corrosion fatigue with the presence of water-vapor reduces the total fatigue life. The fatigue life with the CPC treatment is shown to increase the fatigue life due to the protection from the corrosive environment containing water-vapor. Test results are obtained for various stress ratios and frequencies with and without the CPC treatment under constant amplitude fatigue loading in water vapor. The second aspect of this work is to investigate the effect of periodic overloads and the limitation in their spacing cycles on the fatigue life under constant amplitude fatigue loading. The results confirm the earlier work that the fatigue life increases due to the periodic overloads in 2024-T3 aluminum alloy. The interactions between overloads that are controlled by the spacing cycles between overloads are also examined. From scanning electron microscopic work the transition from the ductile to brittle mode is observed clearly in this experimental work.

scholarly journals Assessment of Validity of Selected Criteria of Fatigue Life Prediction

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2310 ◽  
Author(s):  
Krzysztof Kluger ◽  
Roland Pawliczek
Keyword(s):  
Fatigue Life ◽  
Fatigue Loading ◽  
Mean Value ◽  
Material Behavior ◽  
Density Parameter ◽  
Test Results ◽  
Critical Plane Approach ◽  
Calculation Results ◽  
The Mean ◽  
Number Of Cycles

The paper reports on the results of a comparison involving mathematical models applied for fatigue life calculations where the mean load value is taken into account. Several models based on the critical plane approach and energy density parameter were tested and analyzed. A fatigue test results for three types of materials are presented in this paper. The specimens were subjected to bending, torsion and a combination of bending with torsion with mean value of the load. Analysis of the calculation results show that the best fatigue life estimations are obtained by using models that are sensitive to the changes of material behavior under fatigue loading in relation to the specified number of cycles of the load.

Mean Stress Effect on Fatigue of Welded Joint in FPSOs

2006 ◽  
Author(s):  
Bin Zhang ◽  
Torgeir Moan
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Stress Effect ◽  
Mean Stress ◽  
Initial Condition ◽  
Mean Stress Effect ◽  
Structural Details ◽  
The Mean ◽  
Mean Stresses

This paper deals with the mean stress effect on the fatigue life of welded joints in FPSOs. Mean stresses in structural details of FPSOs are composed of residual stresses and mean stresses induced by external service loading conditions. Mean stresses, both the residual stresses and those induced by external load, affect on the fatigue life of structural details. Fatigue strength decreases as tensile mean stress increases. Under compressive mean stresses, fatigue lives are increased. Different fatigue analysis procedures to account for mean stress effect, i.e. JBP, JTP, DNV CN30.7 and IIW procedure, are used to compare the fatigue test data of different specimens representing different typical welded connections in ship-shaped structures from HHI in Korea. In this paper these procedures are compared and an improved procedure explicitly considering of the mean stress effect is also proposed. The fatigue strength of welded joints of FPSO is affected by the initial condition as well as possible redistribution (shake-down) of the residual stresses. The initial condition of welding residual stress and its re-distribution by static preload and cyclic load in the small scale specimens are evaluated with FE analyses and analytical equations, also compared with the test results obtained from measurement based on ordinary sectioning method.

In-Situ Study on Coaxing During Vibration-Based Bending Fatigue of Inconel 625 and 718

2013 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Jeremy Schwartz ◽  
Tommy George ◽  
Charles Cross ◽  
Casey Holycross ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stress Amplitude ◽  
Test Procedure ◽  
Fatigue Loading ◽  
Fatigue Performance ◽  
Step Test ◽  
Inconel 625 ◽  
Bending Fatigue ◽  
Life Data ◽  
Cycles To Failure

This study observes coaxing effects on aerospace nickel alloys during vibration-based bending fatigue loading. The purpose of this analysis is to determine if Goodman diagrams can be constructed using bending fatigue life data at experimentally defined cycles to failure. The methodology for controlling the number of cycles to failure requires a series of understressing steps, where stress amplitude is incrementally increased at each step. This method, known as the step-test procedure, states that, for some materials, the stress amplitude corresponding to the controlled cycles-to-failure can be determined through linear interpolation between the failure step and the previous non-failure step. Using the step-test procedure, experimental bending fatigue life results were gathered from cold-rolled Inconel 625 and 718 plate specimens. These bending loads are applied with a vibration-based experimental method, known as the George fatigue method, which utilizes modal vibration for fatigue loading. The fatigue life results from the George fatigue method are compared to life data from previously published constant stress amplitude experiments to determine if coaxing affects the fatigue performance of the Inconel materials. Results show that Inconel 625 has an improved fatigue performance that could be attributed to several possible factors, including coaxing, while the Inconel 718 data is shown to be within a 50% confidence band of constant stress amplitude data from the same material stock. The findings in this study increases the knowledge necessary to attain more relevant and less conservative empirical data for designing against high cycle fatigue (HCF) failure of complex gas turbine engine components.

Mean Stress in Algorithms Estimating Fatigue Life of Selected Structural Materials

2016 ◽  
Vol 250 ◽  
pp. 50-55
Author(s):  
Krzysztof Kluger ◽  
Roland Pawliczek
Keyword(s):  
Fatigue Life ◽  
Energy Density ◽  
Mathematical Models ◽  
Fatigue Loading ◽  
Mean Value ◽  
Material Behavior ◽  
Density Parameter ◽  
Mean Stress ◽  
Critical Plane ◽  
The Mean

The paper presents comparison of the mathematical models for fatigue life calculations including influence of the mean load value. Several model based on stress analysis on the critical plane and energy density parameter were investigated. In this paper three types of materials were tested and subjected to bending, torsion and combination of bending with torsion loading with the participation of mean value of the load. It was found, that the best fatigue life estimations obtained by models taking into account changes of the material behavior under fatigue loading related to the specified numbers of cycles of the load.

Fatigue Life of the Human Teeth: A Continuum Damage Approach

2019 ◽  
Vol 43 ◽  
pp. 1-19
Author(s):  
Theddeus Tochukwu Akano
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Stress Amplitude ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Elastoplastic Model ◽  
Human Teeth ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

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