The Automatic Generation of Finite Element Models for Different Analysis Levels

Most of researches for large-scale parallel structural analysis using finite element method have focused on iterative solution methods since direct solution methods generally have many difficulties and disadvantages for large-scale problems. However, due to the numerical robustness of direct methods that guarantees the solution to be obtained within estimated time, direct methods are much more desirable for general application of large-scale structural analysis, as well as due to ease of use which makes most of structural engineers prefer direct methods. In this research, we propose a parallel direct solver for large-scale finite element analysis that can overcome most of difficulties and disadvantages of direct methods by using domain-wise approach for direct methods. By using the proposed solver with our own structural analysis code, we can show good scalability as a direct method and can solve the largest problem ever solved by direct solvers.

Summary form only given. Time-domain electric field integral equations (TD-EFIE) are widely used for analyzing transient scattering from perfect electrically conducting surfaces. These equations often are solved via marching-on-in-time (MOT) methods. Unfortunately, the computational cost of classically formulated MOT-based TD-EFIE solvers scales as O(N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) where N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> are the number of time steps and spatial surface unknowns, respectively. This cost prevents these solvers from being used to study high-frequency phenomena involving large-scale structures.In the past, a variety of methods for accelerating MOT-based TD-EFIE solvers have been developed; they include, but are not limited to, hybrid TD-EFIE and time domain physical optics (TDPO) methods, and fast summation schemes such as the time-domain adaptive integral method (TD-AIM). In the hybrid TD-EFIE-PO method, structures are partitioned into EFIE and PO regions. In the EFIE region, surface currents are updated by MOT; incident fields comprise those produced by external sources and currents in the PO region. In the PO region, currents are updated using incident fields produced by external sources and currents in the EFIE region (W. Luo, W. Y. Yin, M. D. Zhu, J. Y. Zhao, and J. F. Mao, IEEE Trans. Electromagn. Compat., 54, 1006-1016, 2012). The asymptotic computational complexity of the TD-EFIE-PO scheme scales like that of the TD-EFIE scheme albeit with a far smaller leading constant, enabling the solution of much larger problems. The TD-AIM constitutes the extension of the frequency domain adaptive integral method to the time domain, and reduces the computational complexity of a TD-EFIE solver from O(NtNs ) to 2 O ( N t N s log N s ) without any (high-frequency) 3/2 2 assumptions on the current (A. E. Yılmaz, J. M. Jin, and E. Michielssen, IEEE Trans. Antennas Propag., 52, 2692-2708, 2004). This paper presents a solver that hybridizes the TD-EFIE-PO and TD-AIM methods. In the hybrid scheme, the TD-AIM is used to propagate fields within the EFIE region as well as from the EFIE to the PO region, and back. The hybrid scheme is computationally far more efficient than its standalone constituents. Depending on the nature of the structure considered, the TD-AIM method uses a single grid that covers both the EFIE and PO regions, or separate and nonoverlapping grids for both regions. We apply the proposed scheme to the analysis of interactions of high-power electromagnetic pulses (HP-EMP) with large-scale platforms. Numerical results demonstrate the efficiency, accuracy, and stability of the proposed method.

&lt;p&gt;The analysis of the new football stadium roof raised a bunch of analytical problems mainly connected with the large volume of information to be processed rather than the scale of the structure itself. The paper discusses some of those problems, methods of their solution as well as some tricks aimed at decreasing the amount of data and improving the analytical performance for the structural analysis of large scale structures.&lt;/p&gt;

Long-tailed distributions and non-uniform expansion in the analysis of large-scale structure

In the last decade, parallel processing has come to be widely used in the analysis of large-scale structures. This chapter is devoted to the optimal decomposition of structural models using graph theory approaches. First, efficient graph theory methods are presented for the optimal decomposition of space structures. The subdomaining approaches are then presented for partitioning of finite element models. A substructuring technique for the force method of structural analysis is discussed.

Evaluation of the Plio-Quaternary tectonic stress regime from fault kinematic analysis in the lake Van Basin (Eastern Anatolia)

The analysis of large-scale structures from highly refined unsteady simulations becomes challenging as the mesh resolution increases, and some new tools must be developed in order to perform their identification and extraction. A solution is to use filters to remove the smallest flow motions. High-order filters, characterized by their good selectivity properties, were implemented in an unstructured finite-volume solver for large-eddy simulation, and their ability to extract structures of a given scale was tested on canonical flows. Then, these filters were applied on an aeronautical swirl burner with a complex geometry. The results show that novel high-order filters are able to extract the precessing vortex core from this realistic turbulent flow. High-order filtering enables to study in detail this large-scale structure and to gain insight into the dynamic of swirl flows.

Distributed parallel computing, which uses general purpose workstations connected by a network as a large parallel computing resource, is one of the most promising trends in parallel computing. With this technique, existing computing resources can be utilized effectively and the supercomputing power can be achieved through the networked workstations without additional expenditures to buy the expensive supercomputers. The parallel finite element method using domain decomposition has been adapted to the distributed parallel environment of networked workstations. Using the developed code, several model problems have been solved and the parallel performances have been tested on the network of eight IBM RS/6000 230 workstations. Finally, a very large size structural analysis problem with over 368,000 DOFs has been solved using 36 IBM RS/6000 380 workstations connected by a network.

A smart component model replacement approach for refined simulation of large nonlinear RC structures

Simple and efficient finite element modeling of reinforced concrete columns confined with fiber-reinforced polymers

ABSTRACTRecent works have shown that weak lensing magnification must be included in upcoming large-scale structure analyses, such as for the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), to avoid biasing the cosmological results. In this work, we investigate whether including magnification has a positive impact on the precision of the cosmological constraints, as well as being necessary to avoid bias. We forecast this using an LSST mock catalogue and a halo model to calculate the galaxy power spectra. We find that including magnification has little effect on the precision of the cosmological parameter constraints for an LSST galaxy clustering analysis, where the halo model parameters are additionally constrained by the galaxy luminosity function. In particular, we find that for the LSST gold sample (i &amp;lt; 25.3) including weak lensing magnification only improves the galaxy clustering constraint on Ωm by a factor of 1.03, and when using a very deep LSST mock sample (i &amp;lt; 26.5) by a factor of 1.3. Since magnification predominantly contributes to the clustering measurement and provides similar information to that of cosmic shear, this improvement would be reduced for a combined galaxy clustering and shear analysis. We also confirm that not modelling weak lensing magnification will catastrophically bias the cosmological results from LSST. Magnification must therefore be included in LSST large-scale structure analyses even though it does not significantly enhance the precision of the cosmological constraints.

Base on the underground central business district project in the south economic development zone of Changchun, this research studied seismic performance of a large-scale complex underground commercial space structure under the severe earthquake action. A three-dimensio nal dynamic model was established with the finite element program MIDAS/GTS. The response of the main structure was obtained using time history analysis method, including the storey relative displacement and storey drift angle between adjacent structures. The numerical results show that the structure can satisfy the requirements of the seismic performance under the severe earthquake action. The results could be regarded as a valuable reference in design practice.

In the development of industrial machines, trial production is very expensive in terms of cost and man-hour. For this reason, the reworking to the design which occurs at the time of trial production is minimized, and no trial production by calculation is demanded. On the other hand, at the mold clamping device of the injection molding machine, complicated contact by the link mechanism is dynamically and statically intertwined, and it is considered that evaluation by static analysis of conventional parts alone is difficult. Therefore, we applied a mechanism-structure simulator that can take into consideration the many-body contact developed by our company to clamping device analysis. In this paper, we report on the comparison between analysis value and measured value of the dynamical displacement at stationary platen and axial force of ball screw.

A global–local approach for progressive damage analysis of fiber-reinforced composite laminates

A simplified formulation of a plate/shell element for geometrically nonlinear analysis of moderately large deflections with small rotations