scholarly journals Reliability Estimation of Transport Means Elements Under the Action of Cyclic Loads and Corrosive Environment

2018 ◽  
Vol 15 (4) ◽  
pp. 5793-5802
Author(s):  
P. V. Popovych ◽  
Volodymyr Dzyura ◽  
O. S. Shevchuk
Keyword(s):  
Fracture Mechanics ◽  
Corrosion Fatigue ◽  
Residual Life ◽  
Fatigue Cracks ◽  
Reliability Estimation ◽  
Analytical Models ◽  
Cyclic Loads ◽  
Corrosive Environment ◽  
17G1s Steel ◽  
Kinetics Of

The approach for determining the residual life of the vehicles’ thin-walled metal elements with cracks under the action of cyclic loads and corrosive environment is developed based on the first law of thermodynamics and the fracture mechanics principles. Based on the results of the mathematical description of electrochemical reactions and separate data of fracture mechanics, the equation describing the kinetics of the corrosion-fatigue cracks propagation is deduced. This equation and the initial and final conditions are a mathematical model for determining the residual life of structural elements. The correctness of the developed analytical models is confirmed by the experimental data known in the literature. The performance of this model is demonstrated on the example of determining the residual life of a plate made of 17G1S steel. The plate was diluted by a crack in a 3% NaCl solution and subjected to cyclic loading. An increase in the initial size of corrosion-fatigue cracks is significant to reduce the period of their subcritical growth.

Investigation and modeling of the kinetics of the development of corrosion-fatigue cracks

1978 ◽  
Vol 13 (3) ◽  
pp. 235-239
Author(s):  
N. N. Vasserman ◽  
V. A. Merkushev ◽  
M. S. Nemanov
Keyword(s):  
Corrosion Fatigue ◽  
Fatigue Cracks ◽  
Kinetics Of

Engineering Method for Assessing the Residual Life of Machines’ Complex Metal Structures Based on Crack Resistance

2020 ◽  
Vol 992 ◽  
pp. 712-717
Author(s):  
S.B. Budrin ◽  
Yu.N. Gorchakov ◽  
V.V. Ovsyannikov ◽  
N.S. Pogotovkina
Keyword(s):  
Fracture Mechanics ◽  
Crack Resistance ◽  
Critical Size ◽  
Residual Life ◽  
Fatigue Cracks ◽  
High Sensitivity ◽  
Weather Conditions ◽  
Metal Structures ◽  
Complex Metal

The authors present the experience of applying their methodology for calculating the residual life of metal structures of reloading machines by the criterion of the development of fatigue cracks to a critical size. The methodology is based on the well-known calculated dependencies of fracture mechanics, refined and supplemented with elements that take into account the specifics of the operation of transshipment machines in difficult weather conditions. Particular attention was paid to the accuracy of determining the stresses in the metalwork element when performing working operations because of the ever changing of the load acting on the metalwork, depending on the weight of the lifted load and the position of the machine in space. To confirm the high sensitivity to the accuracy of the determination of stresses, the dependence of the influence of the resource element metal with a crack from the amplitude of stress is graphically presented. The methodology for assessing the residual resource has been successfully tested on a number of complex metal.

Assessment of the Influence of Corrosive Aggressive Cargo Transportation on Vehicle Reliability

2018 ◽  
Vol 38 ◽  
pp. 17-25 ◽  
Author(s):  
Pavlo Popovych ◽  
Oksana Shevchuk ◽  
Volodymyr Dzyura ◽  
Liubov Poberezhna ◽  
Vasyl Dozorskyy ◽  
...  
Keyword(s):  
Corrosion Fatigue ◽  
Fatigue Cracks ◽  
Kinetic Equations ◽  
Analytical Models ◽  
Metal Structures ◽  
Subcritical Growth ◽  
Thin Walled ◽  
Cargo Transportation

The analytical models for calculating the performance of vehicles used to transport fertilizers have been developed. The durability of undercarriages elements is estimated with consideration of kinetic equations for determining the periods of nucleation and propagation of cracks. The formulas for determining the durability of П-shaped thin-walled sections as the sum of the periods of nucleation and subcritical growth of corrosion-fatigue cracks in metal structures of vehicles, depending on the conditions of operation, are applied as well.

Investigation of the processes of fatigue and corrosion-fatigue destruction of pseudo-α titanium alloy

2021 ◽  
Vol 7 ◽  
pp. 37-48
Author(s):  
A. A. Murashov ◽  
◽  
N. N. Berendeyev ◽  
A. V. Nokhrin ◽  
E. A. Galaeva ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Corrosion Fatigue ◽  
Nuclear Power ◽  
Power Plants ◽  
Fatigue Cracks ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Corrosive Environment ◽  
Β Phase ◽  
Loading Scheme

The paper describes the results of fatigue and corrosion-fatigue tests of the pseudo α titanium alloy PT-3V, which is actively used in nuclear engineering for the manufacture of heat exchange equipment for modern nuclear power plants. Alloy PT-3V has an inhomogeneous coarse-crystalline structure with precipitates of β-phase particles along the grain boundaries of the lamellar shape. It is shown that smooth specimens tested according to the bending-with-rotation loading scheme do not show a noticeable decrease in the cyclic fatigue life when exposed to a neutral corrosive environment (3 % aqueous NaCl solution). However, specimens with a notch (stress concentrator) tested according to the cantilever bending loading scheme demonstrate sensitivity to the action of a corrosive environment at the stages of initiation and growth of fatigue cracks, as evidenced by a significant decrease in the number of cycles before crack initiation, as well as before specimen failure, in comparison with tests in air. Fractographic analysis of fractures of smooth specimens and specimens with a concentrator after fatigue and corrosion-fatigue tests has been carried out. The main stages of the initiation and growth of fatigue cracks are revealed. It has been established that a decrease in the resistance to the initiation and propagation of corrosion-fatigue cracks during testing of notched specimens may be due to the effect of hydrogen embrittlement, accelerated by stress concentration.

scholarly journals Reliability Estimation of Reinforced Slopes to Prioritize Maintenance Actions

2021 ◽  
Vol 18 (2) ◽  
pp. 373
Author(s):  
Farshad BahooToroody ◽  
Saeed Khalaj ◽  
Leonardo Leoni ◽  
Filippo De Carlo ◽  
Gianpaolo Di Bona ◽  
...  
Keyword(s):  
Urban Areas ◽  
Evaluation Method ◽  
Likelihood Function ◽  
Reliability Estimation ◽  
Analytical Models ◽  
Geotechnical Structures ◽  
Reinforced Slopes ◽  
The Stability ◽  
Methods Analytical ◽  
Asset Managers

Geosynthetics are extensively utilized to improve the stability of geotechnical structures and slopes in urban areas. Among all existing geosynthetics, geotextiles are widely used to reinforce unstable slopes due to their capabilities in facilitating reinforcement and drainage. To reduce settlement and increase the bearing capacity and slope stability, the classical use of geotextiles in embankments has been suggested. However, several catastrophic events have been reported, including failures in slopes in the absence of geotextiles. Many researchers have studied the stability of geotextile-reinforced slopes (GRSs) by employing different methods (analytical models, numerical simulation, etc.). The presence of source-to-source uncertainty in the gathered data increases the complexity of evaluating the failure risk in GRSs since the uncertainty varies among them. Consequently, developing a sound methodology is necessary to alleviate the risk complexity. Our study sought to develop an advanced risk-based maintenance (RBM) methodology for prioritizing maintenance operations by addressing fluctuations that accompany event data. For this purpose, a hierarchical Bayesian approach (HBA) was applied to estimate the failure probabilities of GRSs. Using Markov chain Monte Carlo simulations of likelihood function and prior distribution, the HBA can incorporate the aforementioned uncertainties. The proposed method can be exploited by urban designers, asset managers, and policymakers to predict the mean time to failures, thus directly avoiding unnecessary maintenance and safety consequences. To demonstrate the application of the proposed methodology, the performance of nine reinforced slopes was considered. The results indicate that the average failure probability of the system in an hour is 2.8×10−5 during its lifespan, which shows that the proposed evaluation method is more realistic than the traditional methods.

Lifetime Enhancement of Propulsion Shafts Against Corrosion-Fatigue by Laser Peening

2018 ◽  
Author(s):  
Lloyd A. Hackel ◽  
Jon E. Rankin
Keyword(s):  
Corrosion Fatigue ◽  
Fatigue Testing ◽  
Salt Water ◽  
Fatigue Cracks ◽  
Water Immersion ◽  
High Energy ◽  
General Corrosion ◽  
Laser Peening ◽  
Corrosion Pits ◽  
Deep Pits

This paper reports substantially enhanced fatigue and corrosion-fatigue lifetimes of propulsion shaft materials, 23284A steel and 23284A steel with In625 weld overlay cladding, as a result of shot or laser peening. Glass reinforced plastic (GRP) coatings and Inconel claddings are used to protect shafts against general corrosion and corrosion pitting. However salt water leakage penetrating under a GRP can actually enhance pitting leading to crack initiation and growth. Fatigue coupons, untreated and with shot or laser peening were tested, including with simultaneous salt water immersion. Controlled corrosion of the surfaces was simulated with electric discharge machining (EDM) of deep pits enabling evaluation of fatigue and corrosion-fatigue lifetimes. Results specifically show high energy laser peening (HELP) to be a superior solution, improving corrosion-fatigue resistance of shaft and cladding metal, reducing the potential for corrosion pits to initiate fatigue cracks and dramatically slowing crack growth rates. At a heavy loading of 110% of the 23284A steel yield stress and with 0.020 inch deep pits, laser peening increased fatigue life of the steel by 1370% and by 350% in the corrosion-fatigue testing.

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