Finite element modeling of the vocal folds with deformable interface tracking

Alba Granados, Jonas Brunskog, Marek Krzysztof Misztal, Vincent Visseq, and Kenny Erleben

Continuous and prolonged use of the speaking voice may lead to functional speech disorders that are not apparent for voice clinicians from high-speed imaging of the vocal folds’ vibration. However, it is hypothesized that time dependent tissue properties provide some insight into the injury process. To infer material parameters via an inverse optimization problem from recorded deformation, a self sustained theoretical model of the vocal folds is needed. With this purpose, a transversely isotropic three-dimensional nite element model is proposed and investigated. Special attention is paid to the collision and time integration schemes. Accuracy in the deformation process is introduced by means of a topology-adaptive method for deformable interface tracking, called the Deformable Simplicial Complex, which has been previously applied to immiscible uids. For computational reasons, aerodynamic driving forces are derived from Bernoulli’s principle.

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SCA 2014: Symposium on Computer Animation, Copenhagen 21st-23rd July

Conference chairs
Kenny Erleben, University of Copenhagen, Denmark
Julien Pettré, Inria, France
Program chairs
Vladlen Koltun, Adobe Research, U.S.A.
Eftychios Sifakis, University of Wisconsin-Madison, U.S.A.
Poster chair
Jack Wang, University of Hong Kong, China

The ACM SIGGRAPH / Eurographics Symposium on Computer Animation (SCA) is the premier forum for innovations in the software and technology of computer animation. The 13rd annual event unites researchers and practitioners working on all aspects of time-based phenomena. Our focused, intimate gathering, with single track program and emphasis on community interaction, makes SCA the best venue to exchange research results, get inspired, and set up collaborations. We invite submission of original, high-quality work in the form of technical papers and posters. All details can be found in the For Submitters section.

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Photon Differential Splatting for Rendering Caustics

Jeppe Revall Frisvad, Lars Schjøth, Kenny Erleben, and Jon Sporring

We present a photon splatting technique which reduces noise and blur in the rendering of caustics. Blurring of illumination edges is an inherent problem in photon splatting, as each photon is unaware of its neighbours when being splatted. This means that the splat size is usually based on heuristics rather than knowledge of the local flux density. We use photon differentials to determine the size and shape of the splats such that we achieve adaptive anisotropic flux density estimation in photon splatting. As compared to previous work that uses photon differentials, we present the first method where no photons or beams or differentials need to be stored in a map. We also present improvements in the theory of photon differentials, which give more accurate results and a faster implementation. Our technique has good potential for GPU acceleration, and we limit the number of parameters requiring user adjustment to an overall smoothing parameter and the number of photons to be traced.

Computer Graphics Forum early view

Moving Conforming Contact Manifolds and related Numerical Problems

Kenny Erleben

Talk at BIRS workshop on “Computational Contact Mechanics: Advances and Frontiers in Modeling Contact”

Video watch

Slides download

Workshop link

Conforming Contact Manifolds for Multibody Simulations

Vincent Visseq, Ulrik Bonde, Marek K. Misztal and Kenny Erleben

Computer simulation of physical phenomena involving contact mechanics is of great in- terest to many fields of research and industries. New applications, such as biomedical simulations, are appealing for the modelling of soft materials and sliding contact. Several different approaches have been developed over the last four decades to formulate con- tact constraints for numerical simulation methods. In the finite element method, mortar meshes, Lagrange multipliers and penalty approaches are widely used to handle con- tact constraints. We propose to develop a new simulation framework providing conform- ing contact manifolds for deformable multibody dynamics, based on the Moving Meshes framework.

Abstract download

Disjoint Domains Interactions Framework for Hyperelastic Simulations

Ulrik Bonde, Marek K. Misztal, Vincent Visseq and Kenny Erleben

Contact interactions in the modeling of biomechanical systems are often simplified as Dirichlet or Neumann boundary conditions. The aim of this work is to propose a generic framework for the simulation of biomechanical disjoint domains and large transformations.

Abstract download

RPI-MATLAB-Simulator: A tool for efficient research and practical teaching in multibody dynamics

Jedediyah Williams, Ying Lu, Sarah Niebe, Michael Andersen, Kenny Erleben, and Jeff C. Trinkle

We present the RPI-MATLAB-Simulator (RPIsim) as an open source tool for research and education in multibody dynamics. RPIsim is designed and organized to be extended. Its modular design allows users to edit or add new components without worrying about extra implementation details. RPIsim has two main goals: 1. Provide an intuitive and easily extendable platform for research and education in multibody dynamics; 2. Maintain an evolving code base of useful algorithms and analysis tools for multibody dynamics problems. Although research often focuses on a specific subset of problems, work too often begins with developing software in a broader scope simply to realize a test bed for research to begin. It is our hope that RPIsim alleviates some of this burden by decreasing development time, thusly increasing efficiency in research. Further, we aim to provide a practical teaching tool. Because it is a fully working simulator, and since it offers the instant gratification of visualized contact dynamics, RPIsim offers students the opportunity to experiment and explore dynamics in the powerful environment of MATLAB. With multiple built-in simulation methods, and support for a simulation data convention, RPIsim facilitates the fair comparison of methods, including those being developed with RPIsim.

Paper download
RPI MATLAB Simulator here


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