Reliability Simulation and Forecast Based on Virtual Prototype for the Running System of Complicated Equipments

2014 ◽  
Vol 543-547 ◽  
pp. 195-198
Author(s):  
Li Jun Cao ◽  
Hui Bin Hu ◽  
Gui Bo Yu ◽  
Shu Hai Wang
Keyword(s):  
Probability Density ◽  
Local Stress ◽  
Virtual Prototype ◽  
Probability Density Distribution ◽  
Stress And Strain ◽  
Load Spectrum ◽  
Density Distribution Function ◽  
Running System ◽  
Maintenance Cycle ◽  
Damage Theory

The running system is the key part to finish training or battle tasks of complicated equipments. But formidable working conditions influence the measurement of load spectrums and it is difficult to analyze and forecast the reliability of running system. Actual vehicle experiments and virtual prototype are firstly combined to obtain complete load spectrum of running system. According to the materials S-N curve, stress and strain spectrums can be computed. Nominal stress method and local stress and strain method are combined with probability density accumulation damage theory to compute the probability density distribution function. Then, the reliability of running system can be forecasted, which provide adequate reference for the maintenance cycle confirmation and mission reliability prediction.

Non-Equilibrium Statistical Theory of Void Microstructure Evolution in Irradiated Metals

2013 ◽  
Vol 364 ◽  
pp. 568-572
Author(s):  
Xiang Hui Guo ◽  
Hai Yun Hu
Keyword(s):  
Distribution Function ◽  
Statistical Theory ◽  
Density Distribution ◽  
Probability Density ◽  
Microstructure Evolution ◽  
Void Growth ◽  
Probability Density Distribution ◽  
Density Distribution Function ◽  
Void Evolution ◽  
Non Equilibrium

The non-equilibrium statistical theory was used as a theoretical approach to modeling and predicting void evolution in metal materials. Fokker-Plank equation was introduced as the kinetic equation for the void evolution, from which the probability density distribution function of voids could be obtained. From the micro-mechanism of metal's irradiation damage, void growth rate equation was obtained using spherical Weilv model and control diffusion theory, and then was simplified based on appropriate assumptions. According to the probability density distribution function of void, a series of macro-mechanical characteristics caused by void growth can be calculated, such as: the critical radius of the void nucleation, the average radius of void. Thus the correlation between the void microstructure evolution and the macroscopic properties of metals can be achieved.

Theoretical and experimental investigation of the function of the wall flow deflecting ring. A generalized mathematical model for the case of a large number of deflecting rings

1987 ◽  
Vol 52 (6) ◽  
pp. 1440-1453 ◽  
Author(s):  
Krumm Semkov ◽  
Nikolai Kolev ◽  
Vladimír Staněk ◽  
Pavel Moravec
Keyword(s):  
Mathematical Model ◽  
Probability Theory ◽  
Experimental Investigation ◽  
Distribution Function ◽  
Density Distribution ◽  
Probability Density ◽  
Packed Bed ◽  
Probability Density Distribution ◽  
Density Distribution Function ◽  
Wall Flow

Based on the probability theory considerations a probability density distribution function has been derived for the radius on which the liquid, upon hiting the wall flow deflectiong ring, or an element of packing resting on it, is deflected and proceeds descending in a trickle bed column. The obtained probability density distribution function has been used in turn in the model describing the distribution of liquid in columns equipped with the wall flow deflecting rings. The ultimate goal is a reliable theory for optimization of the size and spacing of the wall flow deflecting rings in packed bed columns.

scholarly journals Production decline analysis of shale gas based on a probability density distribution function

2020 ◽  
Vol 17 (2) ◽  
pp. 365-376 ◽  
Author(s):  
Yingzhong Yuan ◽  
Zhilin Qi ◽  
Zhangxing Chen ◽  
Wende Yan ◽  
Zhiheng Zhao
Keyword(s):  
Distribution Function ◽  
Density Distribution ◽  
Probability Density ◽  
Shale Gas ◽  
Distribution Model ◽  
Probability Density Distribution ◽  
Density Distribution Function ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Better Than

Abstract Production decline analysis is a simple and efficient method to forecast production dynamics of shale gas. The traditional Arps decline model is also widely used in the production decline analysis of shale gas, but an obvious error is often generated. Based on the Weibull and χ2 probability density distribution function, the monotonic decreasing production prediction equations of shale gas are established. It is deduced that recently, the widely used Duong model is essentially a Weibull probability density distribution model. Decline analysis results of production data from actual shale gas well and numerical simulations indicate that the fitting results of the Weibull (Duong) model and χ2 distribution model are better than the Arps model whose deviation of early data is large. For a shale gas reservoir with very low permeability, pressure conformance area is small and it is obviously influenced by fractures. Early shale gas production rate mainly contributed to by fractures declines quickly and the later production rate mainly contributed to by the matrix declines slowly over time. The production decline curve has obvious long-tail distribution characteristics and it is a better fit to the data with a χ2 distribution model. As for the increase of permeability, the fitting accuracy of the Weibull (Duong) model gradually becomes better than the χ2 distribution model. Research results provide theoretical guidance for choosing a reasonable production decline model of a shale gas reservoir with a different permeability.

Stochastic Fatigue Reliability Analysis for Torsion Shaft of Military Tracked Vehicles

2014 ◽  
Vol 543-547 ◽  
pp. 199-202
Author(s):  
Hui Bin Hu ◽  
Li Jun Cao ◽  
Shu Xiao Chen ◽  
Xin Wen Cao
Keyword(s):  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Local Stress ◽  
Stress And Strain ◽  
Cycle Fatigue ◽  
Fatigue Reliability ◽  
Tracked Vehicles ◽  
Decoupling Method ◽  
Surface Method ◽  
Damage Theory

There are coupled cases of high-cycle fatigue and low-cycle fatigue in torsion shaft of military tracked vehicles. To accurately analyze the stochastic fatigue reliability of torsion shaft, a new kind of decoupling method for high-cycle fatigue and low-cycle fatigue was firstly put forward. Probability fatigue accumulation damage theory and nominal stress method were combined to analyze high-cycle fatigue. Random response surface method was adopted to fit the life distribution function for low-cycle fatigue. To obtain the high-cycle and low-cycle stochastic fatigue reliability, probability fatigue accumulation damage theory and local stress and strain method were used. Then, composite damages of torsion shaft under high-cycle fatigue and low-cycle fatigue could be achieved based on probability fatigue accumulation damage thoery.

Mathematical Model of the Effective Properties of a Fiber Reinforced Composite with a Linearly Graded Transition Zone

2010 ◽  
Vol 38 (4) ◽  
pp. 286-307
Author(s):  
Carey F. Childers
Keyword(s):  
Mathematical Model ◽  
Transition Zone ◽  
Effective Properties ◽  
Local Stress ◽  
Stress And Strain ◽  
Fiber Reinforced ◽  
Strain Fields ◽  
Shear Moduli ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite

Abstract Tires are fabricated using single ply fiber reinforced composite materials, which consist of a set of aligned stiff fibers of steel material embedded in a softer matrix of rubber material. The main goal is to develop a mathematical model to determine the local stress and strain fields for this isotropic fiber and matrix separated by a linearly graded transition zone. This model will then yield expressions for the internal stress and strain fields surrounding a single fiber. The fields will be obtained when radial, axial, and shear loads are applied. The composite is then homogenized to determine its effective mechanical properties—elastic moduli, Poisson ratios, and shear moduli. The model allows for analysis of how composites interact in order to design composites which gain full advantage of their properties.

scholarly journals Influence of Orthotropy on Biomechanics of Peri-Implant Bone in Complete Mandible Model with Full Dentition

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Xi Ding ◽  
Sheng-Hui Liao ◽  
Xing-Hao Zhu ◽  
Hui-Ming Wang
Keyword(s):  
Orthotropic Material ◽  
Tooth Enamel ◽  
Local Stress ◽  
Isotropic Case ◽  
Stress And Strain ◽  
Isotropic Model ◽  
Bone Interface ◽  
Multiple Data ◽  
Cad Models ◽  
The Impact

Objective.The study was to investigate the impact of orthotropic material on the biomechanics of dental implant, based on a detailed mandible with high geometric and mechanical similarity.Materials and Methods.Multiple data sources were used to elaborate detailed biological structures and implant CAD models. In addition, an extended orthotropic material assignment methodology based on harmonic fields was used to handle the alveolar ridge region to generate compatible orthotropic fields. The influence of orthotropic material was compared with the commonly used isotropic model and simplified orthotropic model.Results.The simulation results showed that the values of stress and strain on the implant-bone interface almost increased in the orthotropic model compared to the isotropic case, especially for the cancellous bone. However, the local stress concentration was more obvious in the isotropic case compared to that in orthotropic case. The simple orthotropic model revealed irregular stress and strain distribution, compared to the isotropic model and the real orthotropic model. The influence of orthotropy was little on the implant, periodontal ligament, tooth enamel, and dentin.Conclusion.The orthotropic material has significant effect on stress and strain of implant-bone interface in the mandible, compared with the isotropic simulation. Real orthotropic mechanical properties of mandible should be emphasized in biomechanical studies of dental implants.

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