scholarly journals The Life Assessment by Linear Cumulative Damage Rule for Cold Dwell Fatigue of Ti-6Al-4V

2021 ◽  
Vol 70 (1) ◽  
pp. 35-40
Author(s):  
Yutaro OTA ◽  
Keiji KUBUSHIRO ◽  
Yasuhiro YAMAZAKI
Keyword(s):  
Cumulative Damage ◽  
Life Assessment ◽  
Dwell Fatigue ◽  
Damage Rule

In-Service Reliability Assessment of Turbine Blade Thermal Barrier Coatings Based on a Novel Cumulative Damage Index Model

2021 ◽  
Author(s):  
He Liu ◽  
Jianzhong Sun ◽  
Shiying Lei
Keyword(s):  
Damage Index ◽  
Cumulative Damage ◽  
Life Assessment ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Service Reliability ◽  
Engine Operation ◽  
Premature Failure ◽  
Covariate Data ◽  
Index Model

Abstract Thermal barrier coating (TBC) has been used widely on turbine blades to provide temperature and oxidation protection. With the turbine inlet temperature continuously increasing, TBCs have become more likely to oxide spallation, leading to premature failure of blade metal substrates. Thus, It is necessary to accurately evaluate the in-service reliability of TBCs for blade life assessment and engine operation safety. Nowadays, it is common to dynamically record aero-engine operating and performance data, called dynamic covariate data, which provides periodic snapshots for obtaining reliability information of engine components. Nevertheless, existing TBC life prediction models that pay adequate attention to dynamic covariate information are rare. This paper focuses on using limited failure samples with associated dynamic covariate data to make in-service reliability assessments of TBCs through a proposed cumulative damage index model. For the demonstration of the proposed approach, an integrated TBC life simulation approach has been introduced, which comprises engine performance, blade thermal, TBC damage, and damage accumulation models. The case study shows that the proposed cumulative damage index model based method provides more stable and accurate results than the traditional statistical method based on failure-time data.

Thermodynamics as a fundamental science of reliability

2016 ◽  
Vol 230 (6) ◽  
pp. 598-608 ◽  
Author(s):  
Anahita Imanian ◽  
Mohammad Modarres
Keyword(s):  
Energy Dissipation ◽  
Entropy Generation ◽  
Damage Model ◽  
Second Law Of Thermodynamics ◽  
Reliability Function ◽  
Cumulative Damage ◽  
Life Assessment ◽  
Irreversible Processes ◽  
Second Law ◽  
Cumulative Hazard

Cumulative hazard and cumulative damage are important models for reliability and structural integrity assessment. This article reviews a previously developed thermodynamic entropy–based damage model and derives and demonstrates an equivalent reliability function. As such, a thermodynamically inspired approach to developing new definitions of cumulative hazard, cumulative damage, and life models of structures and components based on the second law of thermodynamics is presented. The article defines a new unified measure of damage in terms of energy dissipation associated with multiple interacting irreversible processes that represent the underlying failure mechanisms that cause damage and failure. Since energy dissipation leads to entropy generation in materials, it has been shown and experimentally demonstrated that the use of the total entropy generated in any degradation process is measurable and can ultimately be used to represent the time of failure of structures and components. This description therefore connects the second law of thermodynamics to the conventional models of reliability used in life assessment. Any variability in the entropic endurance to failure and uncertainties about the parameters of the entropic-based damage model lead to the time-to-failure distribution. In comparison with the conventional probabilistic reliability methods, deriving the reliability function in terms of the entropy generation can offer a general and more fundamental approach to representation of reliability. The entropic-based theory of damage and the equivalent reliability approach are demonstrated and confirmed experimentally by applying the complex interactive corrosion-fatigue degradation mechanism to samples of aluminum materials.

Cumulative damage rule under sliding wear of White metal

2003 ◽  
Vol 2003.40 (0) ◽  
pp. 315-316
Author(s):  
Yukari Tachi ◽  
Kiyoshi Tamura ◽  
Sotomi Ishihara ◽  
Takahito Goshima
Keyword(s):  
Sliding Wear ◽  
Cumulative Damage ◽  
White Metal ◽  
Damage Rule

Application of Fracture Mechanics to Determine the Remaining Lifetime of the Old Steel Bridges Decks

2015 ◽  
Vol 1111 ◽  
pp. 110-115
Author(s):  
Silvia Mihaela Hernea ◽  
Dorel Boldus ◽  
Anamaria Feier
Keyword(s):  
Fracture Mechanics ◽  
Crack Growth ◽  
Calculation Method ◽  
Bridge Deck ◽  
Steel Bridges ◽  
Cumulative Damage ◽  
Experimental Program ◽  
Steel Bridge ◽  
Classical Calculation ◽  
Damage Rule

This paper presents a procedure based on fracture mechanics to predict the evolution of cracks detected in a part of steel bridge deck, still in operation, and establishing thus remaining lifetime below a certain range of application from future traffic. It is also described an experimental program conducted on samples from available material, to determine the material factors “C” and “m” involved in Paris formula and their use in a calculation procedure for simulating crack growth detected. Finally is presented a comparison with results obtained from a classical calculation method, the cumulative damage rule of Palmergren-Miner.

A Study on the Fatigue Life Assessment for Urban EMU Structure

2007 ◽  
Vol 345-346 ◽  
pp. 283-286
Author(s):  
Jong Duk Chung ◽  
Jang Sik Pyun ◽  
Ouk Sub Lee
Keyword(s):  
Fatigue Life ◽  
Endurance Limit ◽  
Assessment Method ◽  
Cumulative Damage ◽  
Life Assessment ◽  
Random Load ◽  
Urban Transit ◽  
Fatigue Assessment ◽  
Fatigue Life Assessment ◽  
Approach Method

In these days, most urban railway vehicles have been serviced under the random load application. However, it is considered to be a major factor of safety to predict the fatigue life for structures. It is thus required that fatigue assessment method for cumulative damage approach while Korea domestic regulations practices only the only has endurance limit approach. With this endurance limit approach, fatigue life prediction is impossible. In this research, the fatigue assessment for urban transit structure by using of cumulative damage approach method and related theories are presented.

A new cumulative damage rule for multilevel cyclic loading with mean stresses

1996 ◽  
Vol 75 (2) ◽  
pp. R29-R35
Author(s):  
Yu Gui-Lan ◽  
Wang Yue-Sheng ◽  
Gai Bing-Zheng
Keyword(s):  
Cyclic Loading ◽  
Cumulative Damage ◽  
Mean Stresses ◽  
Damage Rule

Corrosion mechanism and fatigue behavior of 2A70-T6 aluminum alloy under alternating corrosion and fatigue

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lei Fu ◽  
Hui Li ◽  
Li Lin ◽  
Qingyuan Wang ◽  
Qi Fan ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Corrosion Fatigue ◽  
Intergranular Corrosion ◽  
Fatigue Behavior ◽  
Cumulative Damage ◽  
Corrosion Mechanism ◽  
Corrosive Environment ◽  
Content Type ◽  
Damage Rule

Purpose Most supersonic aircraft were manufactured using 2A70 aluminum alloy. The purpose of this paper is to study the corrosion mechanism and fatigue behavior of an aircraft in a semi-industrial atmospheric corrosive environment, alternating effects of corrosion and fatigue were used to simulate the aircraft’s ground parking corrosion and air flight fatigue. Design/methodology/approach For this purpose, the aluminum alloy samples were subjected to pre-corrosion and alternating corrosion-fatigue experiments. The failure mechanisms of corrosion and corrosion fatigue were analyzed using microscopic characterization methods of electrochemical testing, X-ray diffraction and scanning electron microscopy. Miner’s linear cumulative damage rule was used to predict the fatigue life of aluminum alloy and to obtain its safe fatigue life. Findings The results showed that the corrosion damage caused by the corrosive environment was gradually connected by pitting pits to form denudation pits along grain boundaries. The deep excavation of chloride ions and the presence of intergranular copper-rich phases result in severe intergranular corrosion morphology. During cyclic loading, alternating hardening and softening occurred. The stress concentration caused by surface pitting pits and denudation pits initiated fatigue cracks at intergranular corrosion products. At the same time, the initiation of multiple fatigue crack sources was caused by the corrosion environment and the morphology of the transient fracture zone was also changed, but the crack propagation rate was not basically affected. The polarization curve and impedance analysis results showed that the corrosion rate increases first, decreases and then increases. Fatigue failure behavior was directly related to micro characteristics such as corrosion pits and microcracks. Originality/value In this research, alternating effects of corrosion and fatigue were used to simulate the aircraft’s ground parking corrosion and air flight fatigue. To study the corrosion mechanism and fatigue behavior of an aircraft in a semi-industrial atmospheric corrosive environment, the Miner’s linear cumulative damage rule was used to predict the fatigue life of aluminum alloy and to obtain its safe fatigue life.

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