Papers by Keyword: Stochastic Finite Element Method

Abstract: In order to obtain material properties of a given system it is convenient in many casesto perform only noninvasive, i.e. boundary measurements. Our interest is then focused on buildingmaterials and their functionality when exposed to heat and moisture. To describe the underlying phenomena of heat and moisture transfer we use Künzel model with stochastic description of materialproperties for its relative simplicity and sufficient accuracy. For the inverse procedure weintend to utilize the Calderón’s problem framework which is regularly used in medical imaging asElectrical Impedance Tomography and is based on knowing Dirichlet-to-Neumann or Neumannto-Dirichlet map.Overall this work serves as a preliminary study of both aforementioned computational models andits goal is therefore to build up a solid foundations for further redefinition of both models in order tofit the realistic loading conditions for building structures.

Abstract: In this contribution we focus on the computational aspects for practical use of the uncertainty propagation in groundwater flow environment using stochastic finite element method based on generalized polynomial chaos (gPC), where the uncertain part is taking place only in the spatial distribution of the transport properties. In recent years, there has been a growing trend towards real world applications in computational mechanics, thus the reduction techniques have become very desirable. Our focus is on efficient Matlab implementation in terms of computational time and memory consumption without modifying the mathematical background.

Abstract: In general it is difficult to obtain the results directly during process of structural reliability designing because of the complexity of the structure. It can calculate the structure reliability and failure probability effectively according to the combination of finite element method and theory of reliability. This paper introduces a method of structure reliability based on finite element method, summarizes a common method which has an important engineering application value to calculate the reliability such as using Monte-Carlo method to calculate reliability analysis combining with finite element method, recommends a common used software to reliability design and shows the process of using the software to reliability analysis.

Abstract: The present work deals with second order statistics of first-ply failure response of geometrically nonlinear laminated composite plate subjected to in-plane tensile loading with random system properties. System properties such as the material properties and lamina plate thickness are modeled as independent random variables.The mathematical formulation is based on higher order shear deformation theory (HSDT) with von-Karman nonlinear kinematics. An efficient C⁰ nonlinear finite element method based on direct iterative procedure in conjunction with a first order perturbation approach (FOPT) is extended successfully and applied for failure problem in random environment and is employed to evaluate the dimensionless mean failure load and variance of failure index by modeling the system properties as basic random variables using Tsai-Wu and Hoffman failure criteria.Typical numerical results are presented to examine the effect of amplitude ratios, boundary conditions, lamination schemes with random system properties for different failure criterion.The results obtained using present solution approach is validated with the results available in the literatures.

Abstract: The stochastic model of chloride diffusion is the foundation of evaluating concrete structures’ reliability in marine environment. In this paper, the random field of chloride diffusion coefficient was described as a group of random variables by local average theory. The chloride distribution matrix, diffusion matrix and nodal concentration vector were expanded by using the Taylor series. The stochastic finite element method was developed, and the mean and standard deviation of the chloride distribution concentration were yielded by the presented method. A numerical example demonstrated the high precision of the stochastic finite element method presented, and the service life of concrete structures could be predicted by the method.

Abstract: The cut-and-fill mining is the main content of the technical system of green coal mining. And it is an effective way for solving the environmental problems and mining the coal under buildings, under railway, under water and over confined aquifer. No matter what kind of filling way, the gob stowing cannot achieve ideal filling effect, the filling effect is random in certain scope. Taking a coal mine as an example, with the aid of stochastic finite element method, the three situations of gob stowing were calculated and analyzed to explore the statistical rule of the ground surface settlement and the stability of surrounding rock because of random variation of gob stowing effect.

Abstract: Since accidents of reinforced concrete structure occur frequently, it is a key issue to ensure the safety and stability of structures during construction. In this paper, each construction cycle was divided into four stages using discrete time method of freezing to establish the computational model. According to random theory, with the characteristics of reinforced concrete structures during construction, a series of recurrence equation is built by stochastic finite element method during construction. Based on a random analysis of practical engineering, the random response time-varying rule of reinforced concrete structure is obtained during construction. The results show that the construction process of reinforced concrete structure could be simulated well based on perturbation stochastic finite element method .Both the mean and standard deviation of deflection of mid-span could be obtained precisely.

Abstract: Several algorithms were proposed relating to the development of a framework of the perturbation-based stochastic finite element method (PSFEM) for nonlinear dynamic problem with random parameters, for this purpose, based on the stochastic virtual work principle , some algorithms and a framework related to SFEM have been studied. An interpolation method was used to discretize the random fields, which is based on representing the random field in terms of an interpolation rule involving a set of deterministic shape functions. Direct integration Wilson- Method in conjunction with Newton-Raphson scheme was adopted to solve finite element equations. Numerical examples were compared with Monte-Carlo simulation method to show that the approaches proposed herein are accurate and effective for the nonlinear dynamic analysis of structures with random parameters

Abstract: A straightforward numerical method for the computation of response of non-linear finite element system with uncertain parameters under stochastic loading is presented. This method is based on the special form of the probability destiny function of the random variables and, in particular, on the Gauss-Hermite integration rules to compute the response. In the method, a direct and simple formulation, which can just be signed as a symbol of function, is given to represent the relationships between random response and the randomness of the system parameters. In this way, it becomes much easier to obtain the response quantities by computing the double integrals, in which the stochastic parameter of the finite element system is considered as one of the integration variables in the computational procedure, as well as the external force with random characteristic. An example shows the performance of the method.

Abstract: Physical properties of element are very complex under fatigue loads.The structural system consisted of elements is not a simple topological structure,which the change of its physical properties is more complex.In order to analyze quantitatively the structural stiffness reliability of different design life,it is important to establish the accurate formula of physical properties decrease. In this paper, the formula of elements’ elastic modulus decrease is deduced by using damage mechanics theory combining with the model of residual strength of element. Moreover, stiffness reliability index of controlling node of truss system is solved by applying the Stochastic Finite Element Method in different service life.