Service Lifetime Estimation of EPDM Rubber Based on Accelerated Aging Tests

2017 ◽  
Vol 26 (4) ◽  
pp. 1735-1740 ◽  
Author(s):  
Jie Liu ◽  
Xiangbo Li ◽  
Likun Xu ◽  
Tao He
Keyword(s):  
Accelerated Aging ◽  
Lifetime Estimation ◽  
Epdm Rubber ◽  
Service Lifetime

scholarly journals Reduction of Structural Loads in Wind Turbines Based on an Adapted Control Strategy Concerning Online Fatigue Damage Evaluation Models

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3429
Author(s):  
Nejra Beganovic ◽  
Jackson Njiri ◽  
Dirk Söffker
Keyword(s):  
Wind Turbine ◽  
Fatigue Damage ◽  
Control Strategy ◽  
Renewable Resources ◽  
Accelerated Aging ◽  
Damage Evaluation ◽  
Variable Control ◽  
Service Lifetime ◽  
Increasing Demand ◽  
Selection Of

In recent years, the rapidly-increasing demand for energy generation from renewable resources has been noticeable. Additional requirements are consequently set on Wind Turbine (WT) systems, primarily reflected in WT size and power rating increases. With the size increase of WT, structural loads/fatigue stress on the wind turbine become larger, simultaneously leading to its accelerated aging and the shortening of its lifetime. The primary goal of this contribution is to establish an approach for structural load reduction while retaining or slightly sacrificing the power production requirements. The approach/control strategy includes knowledge about current fatigue damage and/or damage increments and consists of multi-input multi-output controllers with variable control parameters. By the appropriate selection of the designed Multi-Input Multi-Output (MIMO) controllers, the mitigation of structural loads in accordance with a predefined range of accumulated fatigue damage or damage increments, exactly to the extent required to provide a predefined service lifetime, is obtained. The validation of the aforementioned control strategy is based on the simulation results and the WT model developed by National Renewable Energy Laboratory (NREL). The obtained results prove the efficiency of the proposed control strategy with respect to the reduction of rotor blade bending moments, simultaneously exhibiting no significant impact on the resulting power generation.

scholarly journals The Prediction of CMDB Propellant lifetime Based on Arrhenius accelerated model, Berthelot’s equation and Multi-step Prout-Tompkins Model

2021 ◽  
Vol 2083 (3) ◽  
pp. 032018
Author(s):  
Qiong Wang ◽  
Yan Gu ◽  
Jiao Jiao Du ◽  
Lin Jia ◽  
Lin Jun Zhang
Keyword(s):  
Kinetic Model ◽  
General Model ◽  
Reaction Order ◽  
Accelerated Aging ◽  
Original Data ◽  
Lifetime Estimation ◽  
Vital Parameter ◽  
Safe Storage

Abstract Different models were provided to predict the storage lifetime of propellants more accurately. The stabilizer was recognized as a vital parameter for double based propellants’ storage lifetime estimation. The stabilizer contents of a certain RDX-CMDB propellant were traced during the accelerated aging tests. Based on that, the safe storage lifetime of this propellant were predicted using the Berthelot’s equation, Arrhenius accelerated equation and the advanced kinetic model, respectively. The predicted results were compared and the causes were analysed. It found that the biggest disadvantage of Berthelot’s equation and Arrhenius accelerated equation is that the predicted results are significantly affected by the original data. In details, the minor difference of original data will bring tremendous errors when extrapolating to normal temperature. The general model which can be used to depict complex reactions adopted in AKTS software was preferred compared to reaction order (RO) model and Prout-Tompkins (PT) model.

Accelerated aging and stabilization of radiation-vulcanized EPDM rubber

2000 ◽  
Vol 57 (3-6) ◽  
pp. 405-409 ◽  
Author(s):  
A.A Basfar ◽  
M.M Abdel-Aziz ◽  
S Mofti
Keyword(s):  
Accelerated Aging ◽  
Epdm Rubber

Stabilization of γ-radiation vulcanized EPDM rubber against accelerated aging

1999 ◽  
Vol 66 (2) ◽  
pp. 191-197 ◽  
Author(s):  
A.A Basfar ◽  
M.M Abdel-Aziz ◽  
S Mofti
Keyword(s):  
Accelerated Aging ◽  
Γ Radiation ◽  
Epdm Rubber

Novel Service Lifetime Estimation for an Oil-Damper Rubber Bush for a Railway Vehicle

2013 ◽  
Vol 739 ◽  
pp. 437-441
Author(s):  
Ho Kyung Kim
Keyword(s):  
Spring Constant ◽  
Railway Vehicle ◽  
Repeated Loading ◽  
Lifetime Estimation ◽  
Load Amplitude ◽  
Service Lifetime ◽  
Repeated Loads

A railroad bogie's components experience repeated loading during service. Especially, the oil-damper rubber bush becomes fatigue fractured on the plane between the rubber and the steel stem during service, and this results in inferior performance of the bogie. In this study, in order to offer a proper maintenance method for the bush, a novel service lifetime estimation for an oil-damper rubber bush operating under different repeated loads was proposed by normalizing the degrading rate of its spring constant. When 13,720 N, 11,760 N, and 9,800 N of repeated loads were applied to the rubber bush, final damage fraction was shown to be 63.7%, 50% and 40%, respectively. The normalizing lifetime (N/Nf) can be predicted as a function of damage fraction (D/Df), regardless of the load amplitude, as follows: N/Nf = 0.043 + 0.376(D/Df) + 0.489(D/Df)2.

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

Assessment of Color Stability of Treated Leathers with Silicone Oil and Polyethylene Glycol

2014 ◽  
Vol 1 (1) ◽  
pp. 24-34
Author(s):  
Alireza K. ◽  
Hossein Ahmadi ◽  
Mohsen Mohammadi
Keyword(s):  
Ascorbic Acid ◽  
Polyethylene Glycol ◽  
Treatment Process ◽  
Color Change ◽  
Silicone Oil ◽  
Accelerated Aging ◽  
Color Stability ◽  
Antioxidant Additive ◽  
Before And After ◽  
Aesthetic Values

Lubricants and leather dressings are the most common treatments of dry and water logged historical leathers. Color change has a great importance during the time and treatment process, due to visual and aesthetic values of historic leather relics. Polyethylene glycol (PEG) and silicone oil (SiO) are frequently used leather dressings in the conservation procedures. Therefore, color stability of treated leathers with PEG and SiO were investigated before and after heat accelerated aging. Moreover, application of ascorbic acid was evaluated as an antioxidant additive for PEG (PEG+AA).Color change after treatment and aging were studied by colorimetry technique in the CIE *L*a*b system. Results indicated to severe color alteration in PEG treated and aged leathers with or without ascorbic acid. Whereas, SiO treated samples showed better stability and minimum color shift after aging. Silicone oil was characterized as the best dressing for historical leathers with compared to PEG and PEG+AA, due to its high stability and aesthetical properties.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

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