Showing 5 results for Finite Element Method.
A. R. Safari, M. Ghayour, and A. Kabiri,
Volume 25, Issue 1 (7-2006)
Abstract
It is empirically established that, due to a number of factors involved, a classical (linear) analysis of buckling pressure is impossible. Nonlinear theories of buckling are, therefore, required that involve effective factors such as imperfections and welding effects. In this study, models are developed which are as close to allowable standard deviations as possible. In the next stage, their buckling behavior is investigated both experimentally and numerically using finite element packages ADINA, ANSYS, COSMOS, and MARC based on specific capabilities of each. Results show that reasonable estimates of real buckling pressure will become possible when material and geometrical nonlinearities and initial imperfections are introduced into the analytical system. Finally, in the light of the results obtained, a submarine pressure hull is analyzed.
M. Salimi, M. Jamshidian, A. Beheshti, and A. Sadeghi Dolatabadi,
Volume 26, Issue 2 (1-2008)
Abstract
The mechanical behavior of cold rolled sheets is significantly related to residual stresses that arise from bending and unbending processes. Measurement of residual stresses is mostly limited to surface measurement techniques. Experimental determination of stress variation through thickness is difficult and time-consuming. This paper presents a closed form solution for residual stresses, in which the bending-unbending process is modeled as an elastic-plastic plane strain problem. An anisotropic material is assumed. To validate the analytical solution, finite element simulation is also demonstrated. This study is applicable to analysis of coiling-uncoiling, leveling and straightening processes.
E. Fazeli, F. Behnamfar,
Volume 35, Issue 1 (9-2016)
Abstract
In this paper, first the theory of Improved Applied Element Method (IAEM) is proposed and then an appropriate algorithm and software are developed for analyzing structures behavior until collapse by this method. Then, some examples of structural analysis by the above method and a software developed for this study are presented. The results show that IAEM has the ability to solve the discussed problems more accurately in less time than Finite Element Method (FEM). Moreover, the efficiency of the method for solving large displacements problems is enhanced in this research by introducing nonlinear response indicators. For modification of the stiffness matrix in the nonlinear range, a new method is presented that increases the accuracy of calculation up to 30%.
M. Mohammadimehr, S. Alimirzaei,
Volume 36, Issue 2 (3-2018)
Abstract
In this research, the nonlinear buckling analysis of Functionally Graded (FG) nano-composite beam reinforced by various distributions of Boron Nitrid Nanotube (BNNT) is investigated under electro-thermodynamical loading with considering initial geometrical imperfection. The analysis is performed based on nonlocal elasticity theory and using the Finite Element Method (FEM). Various distributions of BNNT along the beam’s thickness are considered as uniform and decreasing-increasing functionally graded; and the extended mixture model is used to estimate the properties of nano-composite beam. The elastic medium around the smart nano-composite beam is modeled as elastic foundation. The governing equations of equilibrium are derived using energy method and nonlocal elasticity theory; and the critical buckling load is obtained for various boundary conditions such as simply-simply supported (S-S) and clamped-clamped (C-C) using the FEM. The results indicate that with an increase in the geometrical imperfection parameter, the stiffness of nano-composite beam increases and consequently the stability of the system increases. The effect of FG-X distribution type is more than uniform distributions. Also, the critical buckling load of nano-composite beam increases with an increase in the electric field and elastic foundation.
O. Bateniparvar, N. Noormohammadi, A. M. Salehi,
Volume 39, Issue 2 (2-2021)
Abstract
In this paper, Equilibrated Singular Basis Functions (EqSBFs) are implemented in the framework of the Finite Element Method (FEM), which can approximately satisfy the harmonic PDE in homogeneous and heterogeneous media. EqSBFs are able to automatically reproduce the terms consistent with the singularity order in the vicinity of the singular point. The newly made bases are used as the complimentary enriching part along with the polynomial bases of the FEM to construct a new set of shape functions in the elements adjacent to the singular point. It will be shown that the use of the combined bases leads to the quality improvement of the solution function as well as its derivatives, especially in the vicinity of the singularity.
