Physically Realistic Virtual Surgery Using the Point-Associated Finite Field (PAFF) Approach

2006 ◽  
Vol 15 (3) ◽  
pp. 294-308 ◽  
Author(s):  
Suvranu De ◽  
Yi-Je Lim ◽  
Muniyandi Manivannan ◽  
Mandayam A Srinivasan
Keyword(s):  
Finite Element ◽  
Finite Field ◽  
Equations Of Motion ◽  
Biological Tissues ◽  
Virtual Surgery ◽  
Element Analysis ◽  
Surgical Incision ◽  
Levels Of Detail ◽  
Digital Surgery ◽  
Different Levels

The generation of multimodal virtual environments for surgical training is complicated by the necessity to develop heterogeneous simulation scenarios such as surgical incision, cauterization, bleeding, and smoke generation involving the interaction of surgical tools with soft biological tissues in real time. While several techniques ranging from rapid but nonphysical geometry-based procedures to complex but computationally inefficient finite element analysis schemes have been proposed, none is uniquely suited to solve the digital surgery problem. In this paper we discuss the challenges facing the field of realistic surgery simulation and present a novel point-associated finite field (PAFF) approach, developed specifically to cope with these challenges. Based upon the equations of motion dictated by physics, this technique is independent of the state of matter, geometry and material properties and permits different levels of detail. We propose several specializations of this scheme for various operational complexities. The accuracy and efficiency of this technique is compared with solutions using traditional finite element methods and simulation results are reported on segmented models obtained from the Visible Human Project.

Thermal stresses in multilevel interconnections: Aluminum lines at different levels

1997 ◽  
Vol 12 (9) ◽  
pp. 2219-2222 ◽  
Author(s):  
Y-L. Shen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stresses ◽  
Element Analysis ◽  
Future Studies ◽  
Level Lines ◽  
The Finite Element Analysis ◽  
Staggered Arrangement ◽  
Upper Level ◽  
Different Levels

Numerical results on the evolution of thermal stresses in multilevel interconnects are presented. Two levels of aluminum lines with an aspect ratio of unity, aligned vertically or arranged in a staggered manner, are considered by recourse to the finite element analysis. The stresses are found to be significantly higher in the lower-level lines than in the upper-level lines, for both the aligned and staggered arrangements. The stress magnitudes are generally smaller in lines of staggered arrangement, compared to the case of aligned lines. Implications of the present findings are discussed, with directions of future studies highlighted.

scholarly journals Finite Element Analysis of the Multilayered Honeycomb Composite Material Subjected to Impact Loading

2017 ◽  
Vol 54 (1) ◽  
pp. 180-179 ◽  
Author(s):  
Raul Cormos ◽  
Horia Petrescu ◽  
Anton Hadar ◽  
Gorge Mihail Adir ◽  
Horia Gheorghiu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Composite Material ◽  
Experimental Testing ◽  
Finite Element Models ◽  
The Finite Element Method ◽  
Low Velocity ◽  
Element Analysis ◽  
Element Simulation ◽  
Different Levels

The main purpose of this paper is the study the behavior of four multilayered composite material configurations subjected to different levels of low velocity impacts, in the linear elastc domain of the materials, using experimental testing and finite element simulation. The experimental results obtained after testing, are used to validate the finite element models of the four composite multilayered honeycomb structures, which makes possible the study, using only the finite element method, of these composite materials for a give application.

scholarly journals Nonlinear Structural Dynamic Finite Element Analysis Using Ritz Vector Reduced Basis Method

1996 ◽  
Vol 3 (4) ◽  
pp. 259-268 ◽  
Author(s):  
M.S. Yao
Keyword(s):  
Finite Element ◽  
Equations Of Motion ◽  
Computational Cost ◽  
Finite Amplitude ◽  
Basis Vector ◽  
Reduced Basis ◽  
Ritz Vector ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Nonlinear Equations Of Motion

The large number of unknown variables in a finite element idealization for dynamic structural analysis is represented by a very small number of generalized variables, each associating with a generalized Ritz vector known as a basis vector. The large system of equations of motion is thereby reduced to a very small set by this transformation and computational cost of the analysis can be greatly reduced. In this article nonlinear equations of motion and their transformation are formulated in detail. A convenient way of selection of the generalized basis vector and its limitations are described. Some illustrative examples are given to demonstrate the speed and validity of the method. The method, within its limitations, may be applied to dynamic problems where the response is global in nature with finite amplitude.

scholarly journals New Analytical Model Used in Finite Element Analysis of Solids Mechanics

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1401 ◽  
Author(s):  
Sorin Vlase ◽  
Adrian Eracle Nicolescu ◽  
Marin Marin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Equations Of Motion ◽  
Classical Mechanics ◽  
Three Dimensional ◽  
Elastic Solid ◽  
The Finite Element Method ◽  
Governing Equations ◽  
Element Analysis ◽  
Elastic Multibody System

In classical mechanics, determining the governing equations of motion using finite element analysis (FEA) of an elastic multibody system (MBS) leads to a system of second order differential equations. To integrate this, it must be transformed into a system of first-order equations. However, this can also be achieved directly and naturally if Hamilton’s equations are used. The paper presents this useful alternative formalism used in conjunction with the finite element method for MBSs. The motion equations in the very general case of a three-dimensional motion of an elastic solid are obtained. To illustrate the method, two examples are presented. A comparison between the integration times in the two cases presents another possible advantage of applying this method.

Redesign of Structural Vibration Modes by Finite-Element Inverse Perturbation

1981 ◽  
Vol 103 (2) ◽  
pp. 319-325 ◽  
Author(s):  
K. A. Stetson ◽  
I. R. Harrison
Keyword(s):  
Finite Element ◽  
Equations Of Motion ◽  
Structural Vibration ◽  
Vibration Modes ◽  
Element Analysis ◽  
Jet Engine ◽  
First Order ◽  
Plate Elements ◽  
Plates And Shells ◽  
First Order Perturbation

A previously developed technique for redesigning the vibrational properties of structures, by inverting the first-order perturbation analysis of the equations of motion, has been applied to a NASTRAN finite element analysis for plates and shells. The program finds the minimal changes to the thicknesses of the plate elements necessary to effect a given set of changes in the modal frequencies and shapes. Results have been obtained for a flat cantilever plate, a cantilever segment of a cylinder, and for a compressor blade for a jet engine.

Analysis of a High-Speed Flexible Four-Bar Linkage: Part I—Formulation and Solution

1989 ◽  
Vol 111 (1) ◽  
pp. 35-41 ◽  
Author(s):  
F. W. Liou ◽  
A. G. Erdman
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Equations Of Motion ◽  
Computer Code ◽  
Element Analysis ◽  
Virtual Displacement ◽  
Axial Forces ◽  
Direct Integration Method ◽  
Analysis Computer ◽  
Four Bar Linkage

Derived from the principle of virtual displacement, a general finite element analysis computer code (FEMAP) of the flexible four-bar linkage is developed on the Apollo computer. In this part, virtual displacement method is presented as a basic theory for the general formulation of the equations of motion. Based on these results, a general finite element computer code of planar four-bar linkage is developed. All the links of the mechanism are considered to be flexible. The nonlinear terms such as coupling between the rigid body and elastic deformation terms and the effect of the axial forces are included. The Newmark direct integration method is used as solution scheme.

scholarly journals Biomechanical study on the changes of stress in temporomandibular joints after the orthognathic surgery in patients with mandibular prognathism: a 3D finite element study

2020 ◽  
Vol 22 (2) ◽  
Author(s):  
Jingheng Shu ◽  
Quanyi Wang ◽  
Hedi Ma ◽  
Haidong Teng ◽  
Tinghui Zheng ◽  
...  
Keyword(s):  
Finite Element ◽  
Biomechanical Study ◽  
Control Group ◽  
Virtual Surgery ◽  
Stress Distributions ◽  
Element Analysis ◽  
Mandibular Prognathism ◽  
Computed Tomography Images ◽  
Temporomandibular Joints ◽  
Asymptomatic Individuals

Purpose: This study aimed to analyze the changes of the stress distributions in TMJs for the pre- and postoperative patients with mandibular prognathism under unilateral occlusions, a frequent occlusion in mastication. Methods: Pre- and six-mouth postoperative cone-beam computed tomography images of thirteen patients diagnosed with mandibular prognathism were scanned and used to construct complete maxillofacial models, assigned as the Pre and Post group, respectively. Another ten asymptomatic individuals were defined as the Control group. The inhomogeneous properties were assigned to the models. The muscle forces and boundary conditions corresponding to left and right unilateral occlusions were applied on the models. The analysis of variation (ANOVA) was chosen for the comparison among the groups. Results: The results showed that the Pre group had abnormal stress distributions ang higher stress level in TMJs, compared with those of the Post and Control groups. Moreover, from clinical cases, symptoms of temporomandibular disorders (TMDs) always followed with increased stresses. Conclusion: Generally, orthognathic surgeries could improve the stress distribution in TMJs of the patients with mandibular prognathism under the unilateral occlusions. However, the postoperative complications, especially symptoms of TMD, were closely related to changes of stress for patients with mandibular prognathism after orthognathic surgeries. Individual virtual surgery and finite element analysis should be conducted to prevent complications in TMJ.

A Refined Model for a Piezoelectric Transformer

2001 ◽  
Author(s):  
Wolfgang E. Seemann ◽  
Rainer Gausmann
Keyword(s):  
Finite Element ◽  
Equations Of Motion ◽  
Wave Length ◽  
Analytical Models ◽  
Piezoelectric Transformer ◽  
Element Analysis ◽  
Load Impedance ◽  
Inertia Effects ◽  
Rod Theory ◽  
University Of Technology

Abstract This paper is dedicated to Prof. Peter Hagedorn, Darmstadt University of Technology, Germany, on the occasion of his 60th birthday. Usually piezoelectric actuators are nowadays simulated with the help of finite element codes. Analytical models are only used for very simple geometries like beams and plates or in those cases where piezoelectric patches are bonded to a beam or plate. Examples can be found in literature. However, it has to be kept in mind that there are still some problems for which standard finite element codes like ANSYS might get difficulties. One such problem is a piezoelectric transformer with an arbitrary load impedance connected to the electrodes of one of the piezoceramics. Such a system is investigated in this paper. To obtain results which are still valid if the diameter of the rod is not small compared to the wave length, a refined rod theory is used which takes into consideration also the inertia effects due to transverse contraction. To derive the equations of motion and the boundary conditions for such a system Hamilton’s principle for electromechanical systems is used. The equations of motion are solved and compared with experimental results. A comparison with results of a finite element analysis is also given for one special case which could be handled by ANSYS.

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