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Implicit Algorithm (implicit + algorithm)

Distribution by Scientific Domains

Engineering	60%

Selected Abstracts

Interactive animation of cloth-like objects in virtual reality

COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 1 2001
Mark Meyer
Abstract Modeling and animation of cloth have experienced important developments in recent years. As a consequence, complex textile models can be used to realistically drape objects or human characters in a fairly efficient way. However, real-time realistic simulation remains a major challenge, even if applications are numerous, from rapid prototyping to e-commerce. In this paper, we present a stable, real-time algorithm for animating cloth-like materials. Using a hybrid explicit/implicit algorithm, we perform fast and stable time integration of a physically based model with rapid collision detection and response, as well as wind or liquid drag effects to enhance realism. We demonstrate our approach through a series of examples in virtual reality environments, proving that real-time animation of cloth, even on low-end computers, is now achievable. Copyright © 2001 John Wiley & Sons, Ltd. [source]

A unified approach to the implicit integration of standard, non-standard and viscous plasticity models

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 11 2002
René de Borst
Abstract It is shown how modern concepts to integrate the elasto-plastic rate equations of standard plasticity via an implicit algorithm can be generalized to plasticity without an explicitly defined yield surface and to overstress-type models of viscoplasticity, where the stress point can be located outside the loading surface. For completeness, a tangent operator is derived that is consistent with the update algorithm. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Improvement of a frictional contact algorithm for strongly curved contact problems

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2003
M. C. Oliveira
Abstract One of the challenges in contact problems is the prediction of the actual contact surface and the kind of contact that is established in each region. In numerical simulation of deep drawing problems the contact conditions change continuously during the forming process, increasing the importance of a correct evaluation of these parameters at each load step. In this work a new contact search algorithm devoted to contact between a deformable and a rigid body is presented. The rigid body is modelled by parametric Bézier surfaces, whereas the deformable body is discretized with finite elements. The numerical schemes followed rely on a frictional contact algorithm that operates directly on the parametric Bézier surfaces. The algorithm is implemented in the deep drawing implicit finite element code DD3IMP. This code uses a mechanical model that takes into account the large elastoplastic strains and rotations. The Coulomb classical law models the frictional contact problem, which is treated with an augmented Lagrangian approach. A fully implicit algorithm of Newton,Raphson type is used to solve within a single iterative loop the non-linearities related with the frictional contact problem and the elastoplastic behaviour of the deformable body. The numerical simulations presented demonstrate the performance of the contact search algorithm in an example with complex tools geometry. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Implicit J2 -bounding surface plasticity using Prager's translation rule

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 10 2002
Francisco J. Montáns
Abstract A bounding surface J2 -plasticity model that uses Prager's translation rule is presented. The model preserves Masing's rules and is developed from the same ideas as classical infinitesimal J2 -plasticity, resulting in the same formulation with the exception of the algorithm for the computation of the hardening function. Instead of utilizing a loading surface as in a previous formulation, hardening surfaces are introduced; the formulation is similar to that of multilayer plasticity using Prager's rule, presented in previous work. An implicit algorithm based on the radial return concept is used, and the consistent elastoplastic tangent is also developed in closed form. Examples illustrating anisotropic behaviour are presented and compared to that predicted by a multilayer J2 -plasticity model. The model is also applied to a soil dynamics problem to show the robustness of the algorithm and its applicability to complex loading. Copyright © 2002 John Wiley & Sons, Ltd. [source]

One-level Newton,Krylov,Schwarz algorithm for unsteady non-linear radiation diffusion problem

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 10 2004
Serguei Ovtchinnikov
Abstract In this paper, we present a parallel Newton,Krylov,Schwarz (NKS)-based non-linearly implicit algorithm for the numerical solution of the unsteady non-linear multimaterial radiation diffusion problem in two-dimensional space. A robust solver technology is required for handling the high non-linearity and large jumps in material coefficients typically associated with simulations of radiation diffusion phenomena. We show numerically that NKS converges well even with rather large inflow flux boundary conditions. We observe that the approach is non-linearly scalable, but not linearly scalable in terms of iteration numbers. However, CPU time is more important than the iteration numbers, and our numerical experiments show that the algorithm is CPU-time-scalable even without a coarse space given that the mesh is fine enough. This makes the algorithm potentially more attractive than multilevel methods, especially on unstructured grids, where course grids are often not easy to construct. Copyright © 2004 John Wiley & Sons, Ltd. [source]