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- Hilding, D., et al.
(author)
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A computational methodology for shape optimization of structures in frictionless contact
- 2001
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In: Computer Methods in Applied Mechanics and Engineering. - 0045-7825 .- 1879-2138. ; 190:31, s. 4043-4060
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Journal article (peer-reviewed)abstract
- This paper presents a computational methodology for shape optimization of structures in frictionless contact, which provides a basis for developing user-friendly and efficient shape optimization software. For evaluation it has been implemented as a subsystem of a general finite element software. The overall design and main principles of operation of this software are outlined. The parts connected to shape optimization are described in more detail. The key building blocks are: analytic sensitivity analysis, an adaptive finite element method, an accurate contact solver, and a sequential convex programing optimization algorithm. Results for three model application examples are presented, in which the contact pressure and the effective stress are optimized. cr 2001 Elsevier Science B.V. All rights reserved.
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| 2. |
- Klarbring, Anders, et al.
(author)
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Topology optimization of flow networks
- 2003
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In: Computer Methods in Applied Mechanics and Engineering. - 0045-7825 .- 1879-2138. ; 192:35-36, s. 3909-3932
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Journal article (peer-reviewed)abstract
- The field of topology optimization is well developed for load carrying trusses, but so far not for other similar network problems. The present paper is a first study in the direction of topology optimization of flow networks. A linear network flow model based on Hagen-Poiseuille's equation is used. Cross-section areas of pipes are design variables and the objective of the optimization is to minimize a measure, which in special cases represents dissipation or pressure drop, subject to a constraint on the available (generalized) volume. A ground structure approach where cross-section areas may approach zero is used, whereby the optimal topology (and size) of the network is found.A substantial set of examples is presented: Small examples are used to illustrate difficulties related to non-convexity of the optimization problem, larger arterial tree-type networks, with bio-mechanics interpretations, illustrate basic properties of optimal networks, the effect of volume forces is exemplified.We derive optimality conditions which turns out to contain Murray's law, thereby, presenting a new derivation of this well known physiological law. Both our numerical algorithm and the derivation of optimality conditions are based on an e-perturbation where cross-section areas may become small but stay finite. An indication of the correctness of this approach is given by a theorem, the proof of which is presented in an appendix. © 2003 Elsevier B.V. All rights reserved.
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| 4. |
- Selskog, Pernilla, et al.
(author)
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Kinematics of the Heart : Finite Element and 3D Time-Resolved Phase Contrast Magnetic resonance Imaging
- 2002
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In: Proceedings of 9th Workshop on The Finite Element Method in Biomedical Engineering, Biomechanics and Related Fields.
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Conference paper (peer-reviewed)abstract
- The complex three-dimensional structure of the heart muscle (myocardium) has anisotropic, non-linear and time-dependent mechanical properties. During the cardiac cycle, the myocardium undergoes large elastic deformations as a consequence of the active muscle contraction along the muscle fibers and their relaxation, respectively. A four-dimensional (4D) description (three spatial dimensions + time) of the mechanical properties of the myocardium would be of interest in the assessment of myocardial function. Time-resolved 3D phase contrast MRI makes it possible to quantify all three velocity components, which is necessary to as accurately as possible describe the velocities in the heart. The velocity data may be used for investigation of the deformation of the heart and calculation of strain in the myocardial wall. We present a method for estimation of myocardial kinematics using finite elements and 3D time-resolved phase contrast MRI.
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