A novel predictor–corrector algorithm for sub‐structure pseudo‐dynamic testing

Two heterogeneous algorithms for partitioned analysis of nuclear power plants considering soil-structure interaction

Performance of the quadrilateral overlapping elements combined with implicit time integration method in solving the transient wave propagations

A study on the bi-directional springback of sheet metal stamping

In spite of important differences in structural response to near‐fault and far‐fault ground motions, this paper aims at extending well‐known concepts and results, based on elastic and inelastic response spectra for far‐fault motions, to near‐fault motions. Compared are certain aspects of the response of elastic and inelastic SDF systems to the two types of motions in the context of the acceleration‐, velocity‐, and displacement‐sensitive regions of the response spectrum, leading to the following conclusions. (1) The velocity‐sensitive region for near‐fault motions is much narrower, and the acceleration‐sensitive and displacement‐sensitive regions are much wider, compared to far‐fault motions; the narrower velocity‐sensitive region is shifted to longer periods. (2) Although, for the same ductility factor, near‐fault ground motions impose a larger strength demand than far‐fault motions—both demands expressed as a fraction of their respective elastic demands—the strength reduction factors Ry for the two types of motions are similar over corresponding spectral regions. (3) Similarly, the ratio um/u0 of deformations of inelastic and elastic systems are similar for the two types of motions over corresponding spectral regions. (4) Design equations for Ry (and for um/u0) should explicitly recognize spectral regions so that the same equations apply to various classes of ground motions as long as the appropriate values of Ta, Tb and Tc are used. (5) The Veletsos–Newmark design equations with Ta=0.04 s, Tb=0.35 s, and Tc=0.79 s are equally valid for the fault‐normal component of near‐fault ground motions. Copyright © 2001 John Wiley & Sons, Ltd.

A procedure for calculating sensitivity coefficients of one-dimensional parabolic mixed initial-boundary value problems is developed. The method is based upon the use of implicit time integration and Newton's method in solving the governing equations. The link between the sensitivity coefficients and the solution method is studied with particular emphasis on the use of adaptive gridding and variable time stepping. The method is employed in the analysis of two model freely propagating premixed laminar flames. The numerical accuracy of the sensitivities is verified and their values are utilized for interpretation of the model results.

In molecular dynamics simulations, the limited time step size has been a barrier to simulating long-time behaviors. Implicit time integration methods allow markedly larger time steps than the standard explicit time method, although they have major drawbacks such as overheads solving linear systems and instability of Newton iterations. To overcome these issues, we propose a semi-implicit time integration scheme, the semi-implicit Hessian correction (SimHec) scheme, for overdamped Langevin dynamics. The method focuses on the Hessian matrices of bonded and nonbonded interactions, where components with large negative Hessian eigenvalues are cut off in the linear approximation of momentum equations to avoid instability. The narrow band Hessian matrix enables an efficient parallelized linear solution with an overlapping approximation. We tested SimHec for the interdomain fluctuations in adenylate kinase and the powerstroke transition of myosin II using a coarse-grained protein model. SimHec reproduced the same dynamics as the explicit method, although the transition dynamics tended to be accelerated and fluctuations in bonded potentials were slightly reduced. These deviations were corrected using a hybrid method, SimHec-H, which adds explicit time steps after the semi-implicit time step. The proposed scheme allowed us to use time steps 50-200 times larger than those in explicit time integration, which resulted in a speedup factor of 7-30 taking the overhead into account.

SummaryTo improve the computational efficiency of the numerical manifold method for discontinuous deformation simulations, a spatial‐domain coupled explicit‐implicit time integration algorithm is proposed. A subdomain partition algorithm based on a super manifold element is developed for the numerical manifold method to simulate dynamic motions of blocky rock mass. In different subdomains, explicit or implicit time integration method is employed respectively based on its contact and motion status. These subdomains interact through assembling the corresponding explicit or implicit time integration‐based matrices of different rock blocks. The computational efficiency of the discontinuity system under dynamic loading is improved by partially diagonalizing the global matrices. Two verification examples of a sliding block along an inclined plane under a horizontal acceleration excitation and a multiblock system acted on by dynamic forces are studied to examine the accuracy of the proposed numerical method, respectively. A highly fractured rock mass situated on an inclined slope subjected to seismic excitations is then studied to show the computational efficiency of the developed algorithm. The simulated results are in good agreement with those from the versions using purely implicit or explicit time integration algorithm for the numerical manifold method. The computational efficiency is shown to be higher using the proposed algorithm, which demonstrates its potential for application in dynamic analysis of highly fractured rock masses.

Implicit time integration methods have been used extensively in numerical modelling of slowly varying phenomena in systems that also support rapid variation. Examples include diffusion, hydrodynamics and reaction kinetics. This article discusses implementation of implicit time integration in plasma codes of the “particle-in-ce1l” family, and the benefits to be gained.KeywordsPolarization MotionSpatial SmoothingParticle EquationFluctuation SpectrumPlasma SlabThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

A hybrid Newton/time-integration procedure for the solution of steady, laminar, one-dimensional, premixed flames

In The present work the method of Higher Order Finite Strip, based on Auxiliary Nodular Line (ANL) technique, was utilized to analyze the forced vibration of the Simply Supported Box Girder Bridges with cross intermediate diaphragms, Also to find out the dynamic response under moving vehicles loads by means of Newmark's method which falls within the Implicit Time Integration methods. The Bridge Mass Matrix and the Consistent Mass Matrix was used for both bending and in plane actions. While the Guyan Reduction method was used for reducing the Bridge System Matrix through omitting the Freedom Degrees belonging to the Auxiliary Nodular Line for both bending and in plane actions, In order to enable the Higher Order Finite Strip method for analyzing the box girder with cross intermediate diaphragms. vehicle model were used in the analysis is the Moving Force (MF) where the vehicle represents a no. of moving force with a value equal to the weight of the vehicle wheel.

A combined finite element and finite difference scheme for computer simulation of microstructure evolution and its application to pore–boundary separation during sintering

An efficient thin layer equivalent technique of SETD method for thermo-mechanical multi-physics analysis of electronic devices

The numerical solution of neutral functional differential equations by Adams predictor- corrector methods

AIAA, Aerospace Sciences Meeting and Exhibit, 34th, Reno, NV, Jan. 15-18, 1996 An efficient computational approach for the analysis of unsteady internal planar viscous airflows with geometry in relative rigid-body motion is presented. The efficiency of the computational approach is obtained through the use of a data-input structure based on a geometry model, a deforming multiblock structured grid, an automated localized dynamic grid generation method, and an explicit or implicit time-integration method. The approach has been coded into the programs DGNS2D and NPARC2D-DG. The features of the codes are described, and test cases are presented to demonstrate the accuracy and application of the codes. The application of interest is the analysis of the airflow through variable-geometry inlets for high-speed aircraft. Included is the analysis of the inviscid airflow during the unstart/restart operation of the NASA Variable Diameter Centerbody inlet. (Author)

Purpose The purpose of this paper is to develop a block method of order five for the general solution of the first-order initial value problems for Volterra integro-differential equations (VIDEs). Design/methodology/approach A collocation approximation method is adopted using the shifted Legendre polynomial as the basis function, and the developed method is applied as simultaneous integrators on the first-order VIDEs. Findings The new block method possessed the desirable feature of the Runge–Kutta method of being self-starting, hence eliminating the use of predictors. Originality/value In this paper, some information about solving VIDEs is provided. The authors have presented and illustrated the collocation approximation method using the shifted Legendre polynomial as the basis function to investigate solving an initial value problem in the class of VIDEs, which are very difficult, if not impossible, to solve analytically. With the block approach, the non-self-starting nature associated with the predictor corrector method has been eliminated. Unlike the approach in the predictor corrector method where additional equations are supplied from a different formulation, all the additional equations are from the same continuous formulation which shows the beauty of the method. However, the absolute stability region showed that the method is A-stable, and the application of this method to practical problems revealed that the method is more accurate than earlier methods.