Analysis of Fatigue Reliability and Fatigue Life for a High Voltage Valve

2012 ◽  
Vol 479-481 ◽  
pp. 2072-2075
Author(s):  
Ji Kang Bo
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Failure Mode ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
High Voltage ◽  
Failure Probability ◽  
Fatigue Reliability ◽  
Actual Application ◽  
Working Principle

The high voltage valve bears repeated loads and impact in its working state. Fatigue failure or fatigue damage is the most common failure mode of high voltage valves. This work analyzes the working principle and working characteristics of a high voltage valve under a static rated load, and proposes the necessity of the fatigue analysis. The failure probability of the high voltage valve is presented and the service life of the entire valve obtained. To find the part prone to fail, the evaluation of the fatigue life of the high voltage valve is carried out. The fatigue life and safety factor of the high voltage valve is obtained. It is found that the edge joints are easy to fatigue failure, which provides a reference for the actual application and of maintenance the high voltage valve.

Fatigue Reliability Analysis of Turbine of Turbocharger Based on the Endurance Test Profile of Engine

2012 ◽  
Vol 215-216 ◽  
pp. 750-753
Author(s):  
Wang Zheng ◽  
Wei Dong Xing ◽  
A Na Wang ◽  
Li Xin
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Failure Mode ◽  
Fatigue Failure ◽  
Fatigue Reliability ◽  
Endurance Test ◽  
Cycle Number ◽  
Operating Modes ◽  
Critical Location ◽  
The Relationship

For the fatigue failure mode of turbine of turbocharger for vehicle application, the method for fatigue reliability analysis and fatigue life prediction of turbine is studied based on the endurance test profile of engine. Firstly, the critical location of turbocharger turbine with fatigue failure mode is determined. Then, the fatigue stress process of turbine is calculated according to the main operating modes consisted of the endurance test profile of engine. The fatigue strength of critical location of turbine with fatigue failure mode is studied through the fatigue test of imitation specimen, and the relationship between the fatigue life of turbine and stress is developed. Further, according to the endurance test profile of engine, the reliability model of turbine with fatigue failure mode is developed, and the rule that the reliability of turbine with fatigue failure mode changes as the cycle number of endurance test of engine is studied. Finally, the method for determining the reliable fatigue life of turbine is proposed.

Probabilistic Fatigue Damage Analysis of Long Span Suspension Bridge Due to Wind Induced Buffeting

2020 ◽  
Vol 980 ◽  
pp. 275-281
Author(s):  
Hu Jun
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Time History ◽  
Suspension Bridge ◽  
Wind Load ◽  
Strong Wind ◽  
Fatigue Reliability ◽  
Long Span ◽  
Fatigue Damage Analysis ◽  
Fluctuating Wind

In order to consider the fluctuating wind load induced fatigue problem of long span suspension bridge, fatigue reliability formula is modified by assuming the fatigue life is accord with the weibull distribution. Based on the accurate bridge buffeting analysis of time history, the stress time history of components of a suspension bridge in east sea China is simulated, and then the fatigue damages and reliabilities are calculated. The results indicate that the main cables and hangers have enough fatigue reliability under the fluctuating wind load, the fatigue failure will not occur; the stiffening girder has larger fatigue damage, under 40 / (m.s-1) mean wind speed action, the girder of mid-support section’s average fatigue life is only 3.103 years, so the girder’s damage under strong wind action should be taken seriously.

Experimental and Numerical Investigation of Torsion Fatigue of Bearing Steel

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
John A. R. Bomidi ◽  
Nick Weinzapfel ◽  
Trevor Slack ◽  
Sina Mobasher Moghaddam ◽  
Farshid Sadeghi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Normal Stress ◽  
Failure Mechanism ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
Damage Mechanics ◽  
Damage Model ◽  
Bearing Steel ◽  
Fatigue Damage Accumulation

This paper presents the results of torsion fatigue of widely used bearing steels (through hardening with bainite, martensite heat treatments, and case hardened). An MTS torsion fatigue test rig (TFTR) was modified with custom mechanical grips and used to evaluate torsional fatigue life and failure mechanism of bearing steel specimen. Tests were conducted on the TFTR to determine the ultimate strength in shear (Sus) and stress cycle (S-N) results. Evaluation of the fatigue specimens in the high cycle regime indicates shear driven crack initiation followed by normal stress driven propagation, resulting in a helical crack pattern. A 3D finite element model was then developed to investigate fatigue damage in torsion specimen and replicate the observed fatigue failure mechanism for crack initiation and propagation. In the numerical model, continuum damage mechanics (CDM) were employed in a randomly generated 3D Voronoi tessellated mesh of the specimen to provide unstructured, nonplanar, interelement, and inter/transgranular paths for fatigue damage accumulation and crack evolution as observed in micrographs of specimen. Additionally, a new damage evolution procedure was implemented to capture the change in fatigue failure mechanism from shear to normal stress assisted crack growth. The progression of fatigue failure and the stress-life results obtained from the fatigue damage model are in good agreement with the experimental results. The fatigue damage model was also used to assess the influence of topological microstructure randomness accompanied by material inhomogeneity and defects on fatigue life dispersion.

Multi-Axial Fatigue Damage Models of Fiber Reinforced Composites

2004 ◽  
Author(s):  
N. H. Yang ◽  
H. Nayeb-Hashemi ◽  
A. Vaziri
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
Multiaxial Fatigue ◽  
Loading Frequency ◽  
Reinforced Composites ◽  
Damage Models ◽  
Failure Models ◽  
Axial Fatigue

Fiberglass reinforced composites are extensively used in various structural components. In order to insure their structural integrity, their monotonic and fatigue properties under multiaxial stress fields must be understood. Combined in-phase tension/torsion loading is applied to [±45°]4 E-glass/epoxy composite tubes under monotonic and fatigue conditions to determine the effects of multiaxial loading on its failure. Various monotonic and fatigue damage criteria are proposed. These models considered failure mode (failure plane), the energy method and the effective stress-strain method. It is observed for the majority of experiments, the failure initiated at the outer lamina layer at 45° to the tube axis. A damage criterion for multiaxial monotonic loading is proposed considering both normal and shear stress contributions on the plane of failure. The experimental data show an excellent agreement with this proposed model for various loading conditions. Other failure models are currently under investigation utilizing the stresses and strains at the composite laminate as well as stress and strain at the outer lamina layer. Multiaxial fatigue failure models are proposed considering again the plane of failure. Since the plane of the failure is subjected to mean and cyclic stresses (shear and normal) and mean and cyclic strains (shear and normal), the fatigue damage models consider the contributions of these stresses and strains to the fatigue life of the composite tube. In addition to the fatigue damage model based on the plane of failure, a multi-axial fatigue failure model is proposed considering the mean and cyclic energy during fatigue experiments. The experimental data show a good correlation between the proposed damage parameters and fatigue life of specimens with some scatter of the data. Other fatigue failure models are currently under investigation considering the loading frequency and visco-elastic properties of the composite.

Reliability Analysis and Design for Pipe-in-Pipe Pipelines With Centralizers

2015 ◽  
Author(s):  
Steve Mao ◽  
Muhammad Kamal ◽  
Wei Qiao ◽  
Gang Dong ◽  
Brian Duffy
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Fatigue Damage ◽  
Failure Probability ◽  
Probabilistic Method ◽  
Pipeline System ◽  
Limit Function ◽  
Analysis And Design ◽  
Manufacturing Tolerances ◽  
The Given

In this paper, a simplified reliability model is developed to identify how the pipe-in-pipe component uncertainties (manufacturing tolerances of centralizer thickness) influence the fatigue life of the system. The focus is on the reliability analysis with respect to the centralizer thickness. In order to reduce the complexity of the problem, only the centralizer thickness is considered to be a random variable. A limit function is formulated based on the three dimension (3D) finite element analysis. With the help of the probabilistic method, the correlation between the centralizer thickness and the failure probability is investigated. Two examples on pipe-in-pipe pipeline system are analyzed. The first one presents the relationship between centralizer thickness and failure probability for inner and outer pipes. The second one is an application of six mile pipe-in-pipe pipeline system. The failure probability of the fatigue is estimated. The influence of the centralizer thickness decreasing with time due to the abrasion, creep wear and elastic deformation is also considered when computing fatigue life and failure probability. The maximum fatigue damage ratio is calculated based on all trial samples generated considering manufacturing tolerances. If the maximum fatigue damage ratio is less than or equal to the allowable fatigue damage ratio, the failure probabilities with respect to the given centralizer thickness is negligible and the design is acceptable if only considering the influence of the given centralizer thickness. In addition, numerical results show that the maximum fatigue damage ratio possibly exceeds the allowable fatigue damage ratio considering manufacturing tolerances although the deterministic fatigue damage ratio is less than the allowable fatigue damage ratio.

Fatigue Safety Factors for Deepwater Risers

2002 ◽  
Author(s):  
B. Stahl ◽  
H. Banon
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Safety Factor ◽  
Damage Index ◽  
Rational Approach ◽  
Fatigue Reliability ◽  
Safety Factors ◽  
Fatigue Design ◽  
Uncertainty Parameters ◽  
Deepwater Risers

Fatigue life is governed by a number of variables that are highly uncertain. The safety factor on fatigue life is used in a deterministic way to account for the estimated fatigue damage uncertainty. High uncertainties lead to high fatigue safety factors, and vice versa. Evaluation of the uncertainties in the variables governing fatigue design provides a grip on what the safety factor should be. This paper addresses riser fatigue using a fatigue reliability model that is relatively simple but still captures the important elements of the fatigue problem. The bias and uncertainty of stress range are extremely important parameters in design against fatigue. This is due not only to the fact that these parameters are highly uncertain, but also to the fact that they are greatly amplified in the fatigue damage equation by the ‘slope’ m of the S-N curve. The Palmgren-Miner fatigue damage index and the intercept value of the S-N curve are additional important variables in fatigue design. A model for combining wave-induced and vortex-induced vibration (VIV) is introduced together with the best available data and reference to industry work in this technology area. A recently completed joint industry project on riser reliability provides good calibration points for the critical fatigue reliability variables. Reliability and sensitivity studies are performed to demonstrate the effect of the uncertainty parameters. An approach to selecting deterministic fatigue design factors that yield specified reliability targets is developed and illustrated. The study provides a rational approach to selecting safety factors for design of deepwater risers, taking into account both wave and VIV-induced fatigue damage.

Failure analysis and fatigue life prediction of high-speed rail clips based on DIC technique

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110662
Author(s):  
Yan Liu ◽  
Xiujie Jiang ◽  
Qiutong Li ◽  
Huan Liu
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Fatigue Failure ◽  
High Speed ◽  
Experimental Tests ◽  
Image Correlation ◽  
Fe Model ◽  
Rail Transportation ◽  
High Speed Rail ◽  
Dic Technique

With the development of rail transportation, the fatigue failure of rail clips has become an issue, which affects the operational safety of trains. In this study, reasons for the fatigue failure of rail clips were investigated to improve their service life. A digital image correlation (DIC) technique was conducted to obtain strain fields, vibration modes, and natural frequencies of a rail clip. The strain and displacement of a rail clip under dynamic cyclic loading were also obtained. A fastener system refinement model was developed to analyze the static, dynamic, and modal responses of the clip. The experimental tests and modal simulation results were mutually verified. The fatigue life was analyzed based on the verified FE model. The results revealed that the maximum strain and minimum fatigue life occur at the heel of the clip, in good agreement with the actual fracture position. As the amplitude and frequency of dynamic cyclic load increased, the fatigue life of the clip decreased sharply. Moreover, the normal wheel–rail force accompanied by high-frequency rail corrugations accelerated crack initiation and reduced the fatigue life. The findings of this study provide guidance for improving the service life of rail clips.

Experimental Study on Anti-Fatigue Damage Structural Design of Diesel Engine Bearings

2012 ◽  
Vol 214 ◽  
pp. 97-101
Author(s):  
Zhen Jie Guo
Keyword(s):  
Experimental Study ◽  
Fatigue Life ◽  
Diesel Engine ◽  
Service Life ◽  
Fatigue Damage ◽  
Working Conditions ◽  
Structural Design ◽  
Connecting Rod ◽  
Main Bearing ◽  
Modern Times

With higher requirements on energy-saving and environmental protection of diesel engine in the modern times, the loads on main bearing and connecting rod bearing of diesel engine are continuously increased, and also working conditions are even more critical. Bearings are the key moving parts of diesel engine, and play an important influence on reliability, service life and other performances of diesel engine. Therefore, the reasons for fatigue damages to its bearings greatly affect fatigue life. In traditional designs, effects of the problem are studied few. In this paper, therefore, this problem is studied for discussing the formation reasons and solutions for it theoretically.

Fatigue Reliability Evaluation Model of Drillstring in Bending Section of Horizontal Well

2012 ◽  
Vol 490-495 ◽  
pp. 2295-2299
Author(s):  
Yi Fei Yan ◽  
Lu Feng Cheng
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Horizontal Well ◽  
Evaluation Model ◽  
Reference Value ◽  
Reliability Evaluation ◽  
Fair Use ◽  
Bending Stress ◽  
Fatigue Reliability ◽  
Alternating Bending

When drillstring rotates through the bending section of horizontal well, the fatigue damage of drillstring will be caused by alternating bending stress. Therefore, a thought to solve the fatigue reliability problem of drillstring in bending section of horizontal well is proposed. The variable amplitude alternating stress is transformed into equivalent fatigue stress, and the fatigue damage of drillstring is analyzed. Considering Palmgren-Miner rule and S-N curve, the fatigue life and reliability evaluation model of drillstring in bending section of horizontal well is established according to the fatigue reliability theory and probabilistic fracture mechanics. This model can calculate the fatigue damage, fatigue life and reliability of drillstring in the process of drilling and the maximum allowable dogleg angle where the drillstring is under compression and tension. And it has the important reference value for the fair use of drillstring and casing program design.

The Effect of Soil on the Structural Response and Fatigue Life of Free Span for Submarine Pipeline

2015 ◽  
Author(s):  
Jie Dong ◽  
Chen Xuedong ◽  
Bing Wang ◽  
Weihe Guan ◽  
Tiecheng Yang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Flow Velocity ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
Failure Modes ◽  
Structural Response ◽  
Submarine Pipeline ◽  
Velocity Data ◽  
Measured Flow ◽  
Stiffness And Damping

Free span resulting from unevenness of seabed or scour of current is a dangerous status for submarine pipeline. Fatigue failure caused by vortex induced vibration (VIV) is one of the main failure modes for free span. Because of the contact between soil and pipeline, the effect of soil must be considered for the fatigue analysis of free span. In this paper, aimed at one in-service submarine pipeline, the research on the VIV response of free span was investigated considering the effect of stiffness and damping of soil. Furthermore, fatigue damage and fatigue life of free span were evaluated based on the actual measured flow velocity data varied with time. The analysis results have provided support for the maintenance of free span for the submarine pipeline.

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