Estimation Of Durability Research Articles

POROSIMETRY BY DOUBLE-RANDOM MULTIPLE TREE STRUCTURING IN VIRTUAL CONCRETE

Two different porosimetry methods are presented in two successive papers. Inspiration for the development came from the rapidly-exploring random tree (RRT) approach used in robotics. The novel methods are applied to virtual cementitious materials produced by a modern concurrent algorithm-based discrete element modeling system, HADES. This would render possible realistically simulating all aspects of particulate matter that influence structure-sensitive features of the pore network structure in maturing concrete, namely size, shape and dispersion of aggregate and cement particles. Pore space is a complex tortuous entity. Practical methods conventionally applied for assessment of pore size distribution may fail or present biased information. Among them, mercury intrusion porosimetry and 2D quantitative image analysis are popular. The mathematical morphology operator “opening” can be applied to sections and even provide 3D information on pore size distribution, provided isotropy is guaranteed. Unfortunately, aggregate grain surfaces lead to pore anisotropy. The presented methods allow exploration of pore space in the virtual material, after which pore size distribution is derived from star volume measurements. In addition to size of pores their continuity is of crucial importance for durability estimation. Double-random multiple tree structuring (DRaMuTS), presented herein, and random node structuring (RaNoS) provide such information. The latter method will be introduced in a next issue of IA&S.

POROSIMETRY BY DOUBLE-RANDOM MULTIPLE TREE STRUCTURING IN VIRTUAL CONCRETE

Two different porosimetry methods are presented in two successive papers. Inspiration for the development came from the rapidly-exploring random tree (RRT) approach used in robotics. The novel methods are applied to virtual cementitious materials produced by a modern concurrent algorithm-based discrete element modeling system, HADES. This would render possible realistically simulating all aspects of particulate matter that influence structure-sensitive features of the pore network structure in maturing concrete, namely size, shape and dispersion of aggregate and cement particles. Pore space is a complex tortuous entity. Practical methods conventionally applied for assessment of pore size distribution may fail or present biased information. Among them, mercury intrusion porosimetry and 2D quantitative image analysis are popular. The mathematical morphology operator “opening” can be applied to sections and even provide 3D information on pore size distribution, provided isotropy is guaranteed. Unfortunately, aggregate grain surfaces lead to pore anisotropy. The presented methods allow exploration of pore space in the virtual material, after which pore size distribution is derived from star volume measurements. In addition to size of pores their continuity is of crucial importance for durability estimation. Double-random multiple tree structuring (DRaMuTS), presented herein, and random node structuring (RaNoS) provide such information. The latter method will be introduced in a next issue of IA&S.

Power durability dependence on temperature, input power, and structure of electrodes in SAW filters

AbstractThe dependence of power durability on temperature and input power has been studied in detail by using SAW filters with AlMgCu/Ti/AlMgCu/Ti four‐layered electrodes. In SAW filters, acceleration factors of degradation are temperature and input power. These two factors are not independent in actual SAW filters, but it is necessary to control the conditions to keep the independence of these two factors in accelerated deterioration tests. As the results of power durability estimation of four‐layered electrodes taking account of the above point, the activation energy of diffusion showed the value of the bulk diffusion level in tests using 800‐MHz‐band filters, and the dependence of the input power increased in proportion to the frequency of the input power. We also successfully improved the power durability of four‐layered electrodes by modifying the layered structure and increasing the Mg content of the AlMgCu alloy layers. In the former case, the dependence on input power did not change but the absolute level versus the input power was improved. In the latter case the dependence on input power and the absolute level versus the input power did not change but the dependence on temperature increased. © 2012 Wiley Periodicals, Inc. Electron Comm Jpn, 95(4): 33‐40, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10413

Estimation of fatigue durability for RC slabs used PVA short-fiber and light-weight concrete

Estimation of fatigue durability for RC slabs used PVA short-fiber and light-weight concrete

Photo-induced degradation of a-Si:H thin film depending on electrical load conditions

Research on the long-term reliability and durability of photovoltaic (PV) moduleshas beengaining significant importancedue to the long term outside installation of such modules, which can be in place for more than 20 years. For the practical and reasonable estimation of long-term reliability and durability, a detailed understanding of each degradation factor is important. In this work, differences in degradation of a-Si:H thin film, depending on the load conditions during the light irradiance, have been evaluated. Temperature and voltage at the output port of the solar cell have been evaluated in detail and the dominant factors for degradation differences are discussed. Along with therecent rapid and extensive progress in PV module reliability qualification, this work reports on practical results in photo-induced degradation of a-Si:H based thin film solar cells.

MATHEMATICAL MODELS OF PERFORMANCE LONG-TERM STRENGTH HEAT-RESISTANT MATERIAL OF AIRCRAFT ENGINES.

The characteristics of the long-term strength of heat-resistant materials ЕІ437БВД, ЖС6К, ЖС6У, ЕП99 and Х18Н10Т are In the article. These characteristics are often used for manufacturing details of the “hot part” of gas turbine engines. Analytically described characteristics can be used for the calculation of estimation of dura-bility of parts of aircraft engines and other power plants working in high and slowly varying temperature condi-tions, as well as in conditions of cyclic “starts and stops”. The advantage of analytical description of the char-acteristics is the possibility of a more accurate interpolation of the load bearing capacity of heat-resistant alloys at intermediate values of temperatures.

Probability-based durability design software for concrete structures subjected to chloride exposed environments

Although concrete is believed to be a durable material, concrete structures have been degraded by severe environmental conditions such as the effects of chloride and chemical, abrasion, and other deterioration processes. Therefore, durability evaluation has been required to ensure the long term serviceability of structures located in chloride exposed environments. Recently, probability-based durability analysis and design have proven to be reliable for the service-life predictions of concrete structures. This approach has been successfully applied to durability estimation and design of concrete structures. However, currently it is difficult to find an appropriate method engineers can use to solve these probability-based diffusion problems. In this paper, computer software has been developed to facilitate probability-based durability analysis and design. This software predict the chloride diffusion using the Monte Carlo simulation method based on Fick`s second law, and provides durability analysis and design solutions. A graphic user interface (GUI) is adapted for intuitive and easy use. The developed software is very useful not only for prediction of the service life but for the durability design of the concrete structures exposed to chloride environments.

The strain-stress state investigation of structural units of the ballast prism by type SP3-5/UA

In the article the results of analytical and experimental studies of the stressed-and-strained state of load-bearing elements of structure of ballast prism planner of SPZ-5/UA are presented. The analytical research is performed using the finite element method (FEM). Its results are used during realization of performance dynamic tests on durability. On the basis of analysis of the calculation and experimental data obtained the estimation of durability of construction of ballast prism planner SPZ-5/UA under the action of loads corresponding to the different operating modes is executed.

Generalized method for the evaluation of wear in cylindrical involute gears

We develop a method for the predictive estimation of wear and durability of cylindrical gears taking into account the influence of the wear of teeth on the geometric and loading characteristics of the engagement. On the basis of the numerical solution of the problem, we confirm that the influence of wear on the service life of the gear is significant. We also construct the plots that can be used to describe the character of this influence.

The Power Durability Dependence on Temperature, Input Power and Structure of Electrodes in SAW Filter

The dependence of power durability on temperature and input power has been studied in detail by using SAW filter with AlMgCu/Ti/AlMgCu/Ti 4-layered electrodes. In case of SAW filters, acceleration factors of degradation are temperature and input power. These 2 factors are not independent in actual SAW filters, but it is necessary to control the condition to keep the independency of these 2 factors in accelerated deterioration test. As the results of power durability estimation of 4-layered electrodes which had done in consideration of the point above, the activation energy of diffusion showed value of bulk diffusion level in the test using 800MHz band filters, and the dependence of input power was increase in proportion to the frequency of input power. Additionally, we successfully improved power durability of 4-layered electrodes by modifying the layered structure and increasing Mg content in AlMgCu alloy layers. In the former case, the dependency of input power didn't change but the absolute level against input power was improved. On the other hand, the dependency of input power and the absolute level against input power didn't change but the dependence of temperature is increase in the latter case.

Numerical Simulation of Hygro-Thermal Deformation of Concrete Based on Heat and Moisture Transfer

Concrete deformation due to temperature and moisture condition will always develop simultaneously and interactively. The numerical simulation of hygro-thermal deformation of concrete is necessary to be investigated for better serviceability, durability estimation and life prediction. In this paper, a numerical simulation procedure was proposed for hygro-thermal deformation of concrete based on the principle of heat and moisture transfer in porous medium. The procedure comprised an analytic solution of heat and moisture transfer, a calculation of moisture induced stress and a finite element analysis (FEM) of hygro-thermal deformation. The methodology of a software named Coupling Temperature and Moisture Simulation System for concrete (CTMSoft) was represented and developed by a mix programming. The graphical user interface (GUI) of the software was programmed by Visual Basic 6.0 and its real numerical calculation process was conducted by calling Matlab and ANSYS. The efficiency of the CTMSoft was validated by a case analysis of the data of Hundt’s test.

Fracture criterion and durability of brittle materials under conditions of stationary heat and mass transfer

The equation determining the stochastic character of the development of brittle fracture of a loaded material as a result of the extension of a fracture crack in it in the presence of stationary heat and mass transfer has been obtained. It is shown that the evolution of the fracture crack is determined by the increment of the thermodynamic potential of the material with a change in its characteristic dimension (length). Based on the indicated equation, an estimate of the average durability of a loaded material with an internal rectilinear crack under the conditions of stationary heat and mass transfer is made. From the condition of the stationarity of the potential the brittle fracture criterion of the material and the possibility of closing the fracture crack have been established.

Factors affecting the accuracy of durability estimates in the design of automotive V-belt pulleys using finite element analysis

In this study, factors influencing the accuracy of the durability estimation for an automotive V-belt pulley were investigated using finite element analysis (FEA). The bolt load, centrifugal load, and stress history were considered for fatigue life calculations, and their effects on the accuracy of the durability estimation were analysed. The stress history of a pulley that experienced a compressive load induced by belt tension, bolt load, and centrifugal load was determined by performing a consecutive static FEA on the rotating pulley. An estimation of the V-belt pulley fatigue life was based on a damage analysis of 36 load steps. Durability tests for the pulleys were then performed to verify the analysis results. The analysis and experimental results were closely correlated. Additional analyses were performed using the same procedure by isolating each factor and studying its effect on the durability estimation. The results revealed that the bolt load in the pulley analysis was not negligible in improving the accuracy of the analysis, and showed that more stress history must be used for the fatigue life calculations.

Estimating durability of steels at repeated bending impacts

Many components are subjected to repeated impacts, or in some cases these impacts can appear as additional loads. Repeated impacts define a fatigue phenomenon known under the name of Impact Fatigue. Because the strain rate changes the material characteristics it is to expect that the material properties at impact fatigue to be different in regard to those obtained at non-impact fatigue. This paper presents a classification of repeated impact tests, and starting from this a series of parameters used for durability estimation will be analyzed. The high number of parameters used by different authors creates difficulties in comparison the different laboratories results. The importance of the shape and dimensions of specimens, and the stiffness of supports are highlighted. In order to avoid these influences the authors proposed an experimental technique, based on testing of Charpy specimens, in similar conditions as single impact test. A new parameter η is proposed in order to correlate the durability at repeated impacts with the Charpy V Notch (CVN) impact energy.

Outcome of Pulmonary Valve Replacements in Adults after Tetralogy Repair: A Multi-institutional Study

The purpose of this study was to assess the outcome of pulmonary valve replacement (PVR) in adults with moderate/severe pulmonary regurgitation after tetralogy repair, with particular emphasis on patient outcome, durability of valve repair, and improvement in symptomatology. The project committee of the International Society of Congenital Heart Disease undertook a retrospective multi-institutional analysis of PVR. Seven centers participated in submitting data on 93 patients >18 years of age who had the operation performed and follow-up obtained. The average age of PVR was 26+/- years (median 27 years). Time of follow-up after replacement was 3 years (range 4 days-28 years). OUTCOMES/MEASURES/RESULTS: Kaplan-Meier estimates of durability of PVR showed approximately 50% replacement at 11 years. There were two deaths at 6 and 12 months after valve replacement. Right ventricular (RV) size estimated by echocardiography from pre- to postoperative studies decreased in 81% (P < 0.001 testing for equal proportions), but RV systolic function increased in only 36% (P = 0.09). Ability index improved in 59% (P < 0.001) and clinical heart failure status improved in 57% with this problem before PVR. PVR did not improve arrhythmia status in a small group of patients. PVR is associated with low mortality, decrease in RV size and improvement in ability index, and uncertain effects on RV systolic function. Average valve durability was approximately 11 years. Criteria for PVR that will preserve RV function are not clearly identified, and management of these patients remains a difficult enterprise.

Simulation of durability of cylinder liners of an internal combustion engine under vibration cavitation

A method is presented for the experimental and calculated estimation of the reliability of internal combustion engine liners exposed to the cavitational-erosive effect of liquid coolant. Combating corrosion of liners of high-and medium-speed engines has remains important because the life of liners with regard to cavitation erosion is approximately four times shorter than that with regard to the cylinder face wear and parts are rejected on the basis of the maximum allowable depth of erosion pits on the water-cooled surface. The procedure of estimating the durability of liners assumes the successive determination of their amplitude-frequency characteristics, the period of damage accumulation, and the highest erosion rate and then an estimation of the liner durability using the kinetic dependence of wear at the moment when the pit depth reaches 75% of the liner wall thickness. By the example of a 2Ch 8.5/11 engine, a satisfactory correlation is demonstrated between experimental data and the results of engine service.

About Forecasting Durability of Particles of Iron Powders and Sintered Materials

Equations for an estimation of hardness and durability of materials of particles of iron powders in various zones are received. The opportunity of reception of materials with physicomechanical properties above separate zones of particles is shown. By development of technological processes of manufacturing sintered details with demanded physicomechanical properties it is necessary to know the physical characteristics of particles of an initial material, and sintered ensemble with them and their possible limiting values. However, definition of separate mechanical characteristics of particles is impossible because of their small sizes and complex form. Authors attempt to define strength and fluidity of various zones of particles of iron powders and sintered materials on their basis, using a method of microhardness testing.

Selected Problems of Description and Estimation of Durability

Selected Problems of Description and Estimation of Durability The subject of this paper deals with different aspects of durability: physically, technical, safely, innovative and economic. Likewise is presented the basis reasons of usable characteristics losses and some selected durability coefficients.

CRITERIA FOR EVALUATING THE RELIABILITY OF REINFORCED CONCRETE OF HIGHWAY BRIDGES SUPERSTRUCTURES

The basic criteria of an estimation of reliability and durability of ferro-concrete road bridges are generalized. Recommendations for increase of reliability and durability of ferro-concrete road bridges are offered.

Models for Estimating the Durability of Repeated Impacts

Many components from industry are subjected to repeated impacts, or in some cases these impacts can appear as additional loads. Repeated impacts define a fatigue phenomenon known under the name of Impact Fatigue. Because the strain rate changes the material characteristics it is to expect that the material properties at impact fatigue to be different in regard to those obtained at non-impact fatigue. First studies at repeated impacts were made at the middle of 19th Century, but the progress in this field is not as fast as non-impact fatigue, due to experimental difficulties and the lake of standards for impact fatigue tests. This paper presents a classification of repeated impact tests, and starting from this a series of parameters used for durability estimation will be analyzed. The high number of parameters used by different authors creates difficulties in comparison the different laboratories results. The importance of the shape and dimensions of specimens, and the stiffness of bearing are highlighted. In order to avoid these influences the authors proposed an experimental technique, based on testing of Charpy specimens, in similar conditions as single impact test. The paper presents a series of results obtained for additional impacts overlapped to a cyclic load.