Integration of Microstructural Architecture of the Mitral Valve Into an Anatomically Accurate Finite Element Mesh

2012 ◽  
Author(s):  
Rouzbeh Amini ◽  
Inge van Loosdregt ◽  
Kevin Koomalsingh ◽  
Robert C. Gorman ◽  
Joseph H. Gorman ◽  
...  
Keyword(s):  
Finite Element ◽  
Mitral Valve ◽  
Constitutive Models ◽  
Geometrical Model ◽  
Finite Element Models ◽  
Element Mesh ◽  
Microstructural Alterations ◽  
Organ Level ◽  
Collagenous Tissues

Although mitral valve (MV) repair initially restores normal leaflets coaptation and stops MV regurgitation, in long term it can also dramatically change the leaflet geometry and stress distribution that may be in part responsible for limited repair durability. As shown for other collagenous tissues, such changes in geometry and loading reorganize the fiber architecture. In addition, MV interstitial cells respond to the altered stress by undergoing alterations in biosynthetic function, which would affect the load-bearing capabilities of MV and its long-term durability. Thus, investigating the repair-induced MV stress and the concomitant microstructural alterations is a key step in assessing the repaired valve durability. Finite element models have been widely used for stress analysis of the mitral valve [1–3]. Most of these models, however, have employed only basic constitutive models and utilized simplified valve geometry. Above all, they have ignored the complex microstructure of the MV, which is the critical physical link between organ level stresses and cellular function. Thus, in this work we developed an initial method to develop an accurate geometrical model of the ovine MV and map the fiber structure for the purposes of developing high fidelity computational meshes of the MV.

Integration of Microstructural Architecture of the Mitral Valve into an Anatomically Accurate Finite Element Mesh

2012 ◽  
Vol 2012 (4) ◽  
pp. 40
Author(s):  
Rouzbeh Amini ◽  
Inge van Loosdregt ◽  
Kevin Koomalsingh ◽  
Robert C. Gorman ◽  
Joseph H. Gorman ◽  
...  
Keyword(s):  
Finite Element ◽  
Mitral Valve ◽  
Finite Element Mesh ◽  
Element Mesh

Geometrical Comparison between Chinese and European-American Cervical Vertebrae

2012 ◽  
Vol 630 ◽  
pp. 425-430
Author(s):  
Hai Bin Chen ◽  
Li Ying Zhang ◽  
Li Wen Tan ◽  
Shao Xiang Zhang ◽  
Xue Mei Cheng ◽  
...  
Keyword(s):  
Finite Element ◽  
Cervical Vertebrae ◽  
Geometrical Model ◽  
European American ◽  
Finite Element Models ◽  
Western Model ◽  
Significant Difference ◽  
Geometrical Scaling ◽  
Male Cadaver ◽  
Geometrical Difference

Neck finite element models have been extensively applied to design and validate the artificial biomaterials. To date, many finite element models of European-American neck have been proposed. However, the issue that using the geometrical scaling to convert a western model into a Chinese neck model is highly controversial. A Chinese neck model, based on MRI/CT scan images and frozen slice images from a 35-year old male cadaver, was established in this paper to examine the geometrical difference between Chinese and European-American cervical vertebrae. Results showed that at every level of all cervical vertebrae except C2, a significant difference between the geometrical model of the Chinese and European-American cervical vertebrae was revealed. The authors suggested that there might be a significant difference between the Chinese and European-American cervical vertebrae.

A Novel Micro-CT Based Anatomically Accurate Finite Element Model for Simulation-Aided Assessment of Mitral Valve Repairs

2013 ◽  
Author(s):  
Chung-Hao Lee ◽  
Robert C. Gorman ◽  
Joseph H. Gorman ◽  
Rouzbeh Aimini ◽  
Michael S. Sacks
Keyword(s):  
Finite Element ◽  
Mitral Valve ◽  
Mitral Regurgitation ◽  
Constitutive Models ◽  
Element Model ◽  
Tissue Level ◽  
Cellular Level ◽  
Fe Model ◽  
Mitral Valves ◽  
Mechanical Responses

Many surgeons have come to view mitral valve (MV) repair as the treatment of choice in patients with mitral regurgitation (MR) [1]. According to recent long-term studies, the recurrence of significant MR after repair may be much higher than previously believed, particularly in patients with (ischemic mitral regurgitation) IMR [2]. We hypothesize that the restoration of homeostatic normal MV leaflet tissue stress in IMR repair techniques ultimately leads to improved repair durability. Therefore, the objective of this study is to develop a novel micro-anatomically accurate 3D finite element (FE) model that incorporates detailed collagen fiber architecture, accurate constitutive models, and micro-anatomically realistic valvular geometry to investigate the functional mitral valve and to aid in the assessment of the mitral valve repairs, especially the linking between the interstitial cellular deformations at the cellular level, the mechanobiological behaviors at the tissue level and the organ level mechanical responses as normal and repaired mitral valves maintaining their homeostatic state.

Improving finite element results in modeling heart valve mechanics

2018 ◽  
Vol 232 (7) ◽  
pp. 718-725 ◽  
Author(s):  
Emily Earl ◽  
Hadi Mohammadi
Keyword(s):  
Finite Element ◽  
Heart Valve ◽  
Numerical Technique ◽  
Strain Tensor ◽  
Computational Cost ◽  
Constitutive Models ◽  
Least Square ◽  
Computational Time ◽  
Finite Element Models ◽  
Fine Mesh

Finite element analysis is a well-established computational tool which can be used for the analysis of soft tissue mechanics. Due to the structural complexity of the leaflet tissue of the heart valve, the currently available finite element models do not adequately represent the leaflet tissue. A method of addressing this issue is to implement computationally expensive finite element models, characterized by precise constitutive models including high-order and high-density mesh techniques. In this study, we introduce a novel numerical technique that enhances the results obtained from coarse mesh finite element models to provide accuracy comparable to that of fine mesh finite element models while maintaining a relatively low computational cost. Introduced in this study is a method by which the computational expense required to solve linear and nonlinear constitutive models, commonly used in heart valve mechanics simulations, is reduced while continuing to account for large and infinitesimal deformations. This continuum model is developed based on the least square algorithm procedure coupled with the finite difference method adhering to the assumption that the components of the strain tensor are available at all nodes of the finite element mesh model. The suggested numerical technique is easy to implement, practically efficient, and requires less computational time compared to currently available commercial finite element packages such as ANSYS and/or ABAQUS.

Automated Finite Element Modeling of Tube Frame Structure Parametric Design

2002 ◽  
Author(s):  
Robert R. Mayer ◽  
Ashok Vaishnav
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Model Building ◽  
Parametric Design ◽  
Finite Element Mesh ◽  
Frame Structure ◽  
Finite Element Models ◽  
Element Mesh ◽  
Element Modeling ◽  
Finite Element Meshes

This research was intended to address the last step in the development of a tube-frame (termed B2B) parametric crashworthiness model - automated finite element modeling of the parametric design. We have added the generation of finite element models to the previously built Unigraphics Version 16 (UG V16) parametric model, so that finite element models could be quickly built. UG/WAVE was used to design the vehicle parametrically and UG/SCENARIO, a pre- and post-processor integrated in UG, was used to automatically construct the finite element mesh. We established the quality of the finite element meshes, generated for two new designs, which were created by changing overall dimensions of the vehicle. This was done using objective criteria for the finite element mesh. The component data was added to the automatically generated mesh, and the results from the crashworthiness analysis of this model compared favorably with the ‘hand-built’ model using traditional model building techniques. The results from this work will be useful in the development of the parametric design process. The use of automatically generated finite element meshes will also be useful for the automated evaluation of these parametric designs.

Structural Analysis of Light Aircraft Wing Components

2012 ◽  
Vol 225 ◽  
pp. 201-206
Author(s):  
Abdelmunem Bushra ◽  
Mohammed Mahdi ◽  
Mohammed A. Elhadi
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Safety Margin ◽  
Element Model ◽  
Geometrical Model ◽  
Aerodynamic Load ◽  
Element Mesh ◽  
Root Edge ◽  
Safety Margins ◽  
The Finite Element Model

This paper aims to demonstrate the structure analysis of strut-braced wing of a typical manufactured Light-Aircraft by using FEM software (MSC PATRAN/NASTRAN) and determine the safety margin in all of its components, which are useful to determine the structure strength requirements. The geometrical model of the wing was created in CATIA and then exported to PATRAN, which is the modeler to build the finite element model. PATRAN model geometry was modified and prepared to create the mesh. The structural components have various functions and shapes, thus different element mesh was created. After creating the finite element model for all parts, the elements and material properties were assigned and the model was fixed at the spar root edge and strut-braced end, and loaded by distributing the inertia load and aerodynamic load, calculated using (CFD), acting on the rib edge. Then the model was submitted to NASTRAN for linear static analysis. The obtained Stress Results and Safety Margins of each part were calculated and found to be acceptable.

Some Useful Tests for the Finite Element Meshes of Polycrystals With Explicit Account of the Grains and Grain Boundaries

2010 ◽  
Author(s):  
Igor Simonovski ◽  
Leon Cizelj
Keyword(s):  
Finite Element ◽  
Grain Boundaries ◽  
Element Model ◽  
Finite Element Mesh ◽  
Finite Element Models ◽  
Mesh Quality ◽  
Intergranular Cracking ◽  
Element Mesh ◽  
Random Lattice ◽  
Consistency Model

A growing number of computational material science and computational mechanics research is currently devoted to the explicit modeling of microstructures at various length and time scales. The finite element models of grains and grain boundaries in polycrystals include discretization of the grain interior. In addition, grain boundaries are explicitly discretized as cohesive zones with appropriate damage properties to facilitate the simulation of intergranular cracking. Such finite element models may easily involve hundreds of grains and millions of finite elements. They may also be combined with advanced lattice orientation dependent constitutive models, such as for example anisotropic elasticity and crystal plasticity. The complexity of the model, including the random lattice orientations, may therefore represent a serious difficulty in detecting possible issues in the finite element model and the interpretation of the results. A number of self-consistency model-checks are therefore needed to verify the model. Two tests are proposed and demonstrated in the paper. The first is aiming at the assessment of the finite element mesh quality within the grains in terms of the results. The second is primarily aiming at the verification of the consistent modeling of the cohesive layer at the grain boundaries. In addition, some useful information about the finite element mesh quality in terms of results is also given.

scholarly journals Characterization of Exercise-Induced Myocardium Growth Using Finite Element Modeling and Bayesian Optimization

2021 ◽  
Vol 12 ◽  
Author(s):  
Yiling Fan ◽  
Jaume Coll-Font ◽  
Maaike van den Boomen ◽  
Joan H. Kim ◽  
Shi Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Growth Parameters ◽  
Constitutive Models ◽  
Left Ventricular ◽  
Bayesian Optimization ◽  
Fe Model ◽  
Imaging Data ◽  
Growth And Remodeling ◽  
Organ Level ◽  
Exercise Induced

Cardiomyocyte growth can occur in both physiological (exercised-induced) and pathological (e.g., volume overload and pressure overload) conditions leading to left ventricular (LV) hypertrophy. Studies using animal models and histology have demonstrated the growth and remodeling process at the organ level and tissue–cellular level, respectively. However, the driving factors of growth and the mechanistic link between organ, tissue, and cellular growth remains poorly understood. Computational models have the potential to bridge this gap by using constitutive models that describe the growth and remodeling process of the myocardium coupled with finite element (FE) analysis to model the biomechanics of the heart at the organ level. Using subject-specific imaging data of the LV geometry at two different time points, an FE model can be created with the inverse method to characterize the growth parameters of each subject. In this study, we developed a framework that takes in vivo cardiac magnetic resonance (CMR) imaging data of exercised porcine model and uses FE and Bayesian optimization to characterize myocardium growth in the transverse and longitudinal directions. The efficacy of this framework was demonstrated by successfully predicting growth parameters of 18 synthetic LV targeted masks which were generated from three LV porcine geometries. The framework was further used to characterize growth parameters in 4 swine subjects that had been exercised. The study suggested that exercise-induced growth in swine is prone to longitudinal cardiomyocyte growth (58.0 ± 19.6% after 6 weeks and 79.3 ± 15.6% after 12 weeks) compared to transverse growth (4.0 ± 8.0% after 6 weeks and 7.8 ± 9.4% after 12 weeks). This framework can be used to characterize myocardial growth in different phenotypes of LV hypertrophy and can be incorporated with other growth constitutive models to study different hypothetical growth mechanisms.

A High Fidelity, Micro-Structural and Anatomically Accurate 3D Finite Element Model for Functioning Heart Mitral Valve

2013 ◽  
Author(s):  
Chung-Hao Lee ◽  
Pim J. A. Oomen ◽  
Jean Pierre Rabbah ◽  
Neela Saikrishnan ◽  
Ajit Yoganathan ◽  
...  
Keyword(s):  
Finite Element ◽  
Mitral Valve ◽  
Mitral Regurgitation ◽  
Constitutive Models ◽  
Element Model ◽  
Suture Line ◽  
High Fidelity ◽  
Fe Model ◽  
3D Finite Element ◽  
Mechanical Responses

Many surgeons have come to view mitral valve (MV) repair as the treatment of choice in patients with mitral regurgitation (MR) [1]. However, recent long-term studies have indicated that the recurrence of significant MR after repair may be much higher than previously believed, particularly in patients with (ischemic mitral regurgitation) IMR [2]. Since a significant number of these failures result from chordal, leaflet and suture line disruption, it has been suggested that excessive tissue stress and the resulting strain-induced tissue damage are important etiologic factors. We thus hypothesize that the restoration of homeostatic normal MV leaflet tissue stress levels in IMR repair techniques ultimately leads to improved repair durability through restoration of normal MV responses. Therefore, the objective of this study is to develop a novel high-fidelity and micro-anatomically accurate 3D finite element (FE) model that incorporates detailed collagen fiber architecture, realistic constitutive models, and micro-anatomically accurate valvular geometry to connect the cellular function of the MV tissues with the organ level mechanical responses, and to aid in the design of MV repair procedures.

Sign in / Sign up

Export Citation Format

Share Document