Influence Of Stochastic Parameters Research Articles

Dynamic performance of planar mechanism with joint clearance considering stochastic parameters

Due to the influence of working temperature and pressure, collision restitution coefficient, Poisson’s ratio, friction coefficient and other material parameters could range in different intervals. However, the uncertainties and variability of material parameters is usually ignored in most researches. Along with vibration and wear, joint clearance is inevitable and widely exists in mechanical devices, which also should be taken into consideration. In this paper, the kinematic and dynamic equations are developed based on continuous Lankarani-Nikravesh contact model and the modified Coulomb friction model using a typical crank-slider mechanism as the research object. The influence of stochastic parameters (obeying normal distribution) on the dynamic characteristics of crank-slider mechanism is studied. In addition, dynamic analysis of the crank-slider mechanism with cylindrical joint clearance of different sizes is carried out in MATLAB environment. Results show that parameter random uncertainty should also be involved in dynamic models.

A stochastic approach for integrating market and technical uncertainties in economic evaluations of petroleum development

The paper presents a stochastic and economic analysis for petroleum development under uncertain market and technical environments. Mean-reversion with jumps for price forecasting is used to consider market uncertainty, while various scenarios for the reservoir properties and cost are employed to consider technical uncertainty. Monte Carlo simulation is carried out to obtain the feasible range of net present values and internal rates of return. The influence of stochastic parameters is examined through correlation coefficients.

Stochastic elasto-plastic fracture analysis of aluminum foams

Model I quasi-static nonlinear fracture of aluminum foams is analyzed by considering the effect of microscopic heterogeneity. Firstly, a continuum constitutive model is adopted to account for the plastic compressibility of the metallic foams. The yield strain modeled by a two-parameter Weibull-type function is adopted in the constitutive model. Then, a modified cohesive zone model is established to characterize the fracture behavior of aluminum foams with a cohesive zone ahead of the initial crack. The tensile traction versus local crack opening displacement relation is employed to describe the softening characteristics of the material. And a Weibull statistical model for peak bridging stress within the fracture process zone is used for considering microscopic heterogeneity of aluminum foams. Lastly, the influence of stochastic parameters on the curve of stress-strain is given. Numerical examples are given to illustrate the numerical model presented in this paper and the effects of Weibull parameters and material properties on J-integral are discussed.