ADINA Publications

Page 33

The Theory used in ADINA is richly documented in the following books by K.J. Bathe and co-authors


Finite Element Procedures
 

Finite Element Procedures in Engineering Analysis

Numerical Methods in Finite Element Analysis
 


The Mechanics of Solids and Structures — Hierarchical ...


The Finite Element Analysis of Shells — Fundamentals


Inelastic Analysis of Solids and Structures

 
 
To Enrich Life
(Sample pages here)
 

 

Following are more than 700 publications — that we know of — with reference to the use of ADINA. The pages give the Abstracts of some papers published since 1986 referring to ADINA. The most recent papers are listed first. All these papers may be searched using the box:

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In Vivo IVUS-Based 3-D Fluid–Structure Interaction Models With Cyclic Bending and Anisotropic Vessel Properties for Human Atherosclerotic Coronary Plaque Mechanical Analysis

C. Yang1, R.G. Bach2, J. Zheng3, I. Ei Naqa4, P.K. Woodard5, Z. Teng6, K. Billiar7, D. Tang8

1 School of Mathematics, Beijing Normal University, Beijing 100875, China
2 Division of Cardiovascular Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA, and also with the Cardiac Intensive Care Unit, Barnes-Jewish Hospital, St. Louis, MO 63108, USA
3 Mallinkcrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
4 Department of Radiation Oncology, Washington University, St. Louis, MO 63110, USA
5 Mallinkcrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
6 Department of Mathematical Sciences, Worcester Polytechnic Institute, Worcester, MA 01609, USA
7 Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA
8 Department of Mathematical Sciences, Worcester Polytechnic Institute, Worcester, MA 01609, USA

IEEE Trans Biomed Eng., 56(10): 2420–2428, 2009

Abstract: In this paper, a modeling approach combining in vivo intravascular ultrasound (IVUS) imaging, computational modeling, angiography, and mechanical testing is proposed to perform mechanical analysis for human coronary atherosclerotic plaques for potential more accurate plaque vulnerability assessment. A 44-slice in vivo IVUS dataset of a coronary plaque was acquired from one patient, and four 3-D models with fluid–structure interactions (FSIs) based on the data were constructed to quantify effects of anisotropic vessel properties and cyclic bending of the coronary plaque on flow and plaque stress/strain conditions. Compared to the isotropic model (model 1, no bending, no axial stretch), (maximum principal stress) values on the cut surface with maximum bending (where applicable) from model 2 (anisotropic, no bending, no stretch), model 3 (anisotropic, with bending, no stretch), and model 4 (anisotropic with bending and stretch) were, respectively, 63%, 126%, and 345% higher than that from model 1. Effects of cyclic bending on flow behaviors were modest (5%–15%). Our preliminary results indicated that in vivo IVUS-based FSI models with cyclic bending and anisotropic material properties could improve the accuracies of plaque stress/strain predictions and plaque vulnerability assessment. Large-scale patient studies are needed to further validate our findings.

Keywords: Atherosclerotic plaque rupture - cardiovascular - coronary artery - fluid-structure interaction (FSI) - intravascular ultrasound (IVUS)

 

Finite Element Model of the Patched Human Carotid

A.V. Kamenskiy1, I.I. Pipinos1, A.S. Desyatova1, Y.E. Salkovskiy1, L.Y. Kossovich2, I.V. Kirillova2, L.A. Bockeria3, Konstantin M. Morozov3, V.O. Polyaev4, T.G. Lynch1, Y.A. Dzenis1

1 Department of Engineering Mechanics, University of Nebraska-Lincoln, Lincoln, Nebraska, Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska, VA Nebraska-Western Iowa, Omaha, Nebraska
2 Department of Mathematical Theory of Elasticity and Biomechanics, Saratov State University, Saratov, Russia
3 Bakulev Scientific Center for Cardiovascular Surgery RA, Moscow, Russia
4 Department of Surgery and Pathology, Saratov State Medical University, Saratov, Russia

Vasc Endovascular Surg, 43(6):533-541, 2009

Abstract: The hemodynamic effects of carotid artery patching are not well known. Our objective was to develop a fluid-solid finite element model of the endarterectomized and patched carotid artery. Methods: Hyperelastic materials parameters were determined from studies of 8 cadaveric carotids. Blood flow characteristics were based on intraoperative data from a patient undergoing endarterectomy. Wall shear stress, cyclic strain and effective stress were computed as hemodynamic parameters with known association with endothelial injury, neointimal hyperplasia abd atherogenesis. Results: Low wall shear stress, high cyclic strain and high effective stress were identified diffusely in the carotid bulb, at the margins around the patch and in the flow divider. Conclusion: Endarterectomy and Polytetrafluoroethylene patching produce considerable abnormalities in the hemodynamics of the repaired carotid. Advanced mechanical modeling can be used to evaluate different carotid revascularization approaches to obtain optimized biomechanical and hemodynamic results for the care of patients with carotid bifurcation disease.

Keywords:    finite element model – endarterectomy – patching - carotid disease

 

Numerical modelling of the opening process of the three-coating aortic valve

M. Kopernik, J. Nowak

AGH University of Science and Technology, Kraków, Poland

Arch. Mech., 61(3–4):171–193, 2009

Abstract: Numerical modelling of the three-coating human aortic valve is the objective of the paper. The proposed approach is used to select the material properties and the thickness of outer coating of the valve, which are required to obtain the proper work of the valve, which in the present paper is considered as the opening process. Following the previously developed model of the monocoating leaflet of the natural human aortic valve, the model of three-coating valve is prepared. Finite element method (FEM) and sensitivity analysis are used to solve the formulated and selected problems. Two methods of estimation of the valve opening process in numerical models are elaborated on the basis of experimental studies.

Key words: finite element method - aortic valve - sensitivity analysis - opening process - buckling pressure - three-coating leaflet

 

Modeling Upper Airway Collapse by a Finite Element Model with Regional Tissue Properties

C. Xu1, M.J. Brennick2,  L. Dougherty3, D.M. Wootton4

1 Department of Surgery University of Pennsylvania, Philadelphia, PA 19104
2 Center for Sleep and Respiratory Neurobiology Department of
Medicine University of Pennsylvania, Philadelphia, PA 19104
3 Department of Radiology University of Pennsylvania, Philadelphia, PA 19104
4 Department of Mechanical Engineering, The Cooper Union, New York, NY
10003

Med Eng Phys., 31(10): 1343–1348, 2009

Abstract: This study presents a new computational system for modeling the upper airway in rats that combines tagged magnetic resonance imaging (MRI) with tissue material properties to predict threedimensional (3D) airway motion. The model is capable of predicting airway wall and tissue deformation under airway pressure loading up to airway collapse. The model demonstrates that oropharynx collapse pressure depends primarily on ventral wall (tongue muscle) elastic modulus and airway architecture. An iterative approach that involves substituting alternative possible tissue elastic moduli was used to improve model precision. The proposed 3D model accounts for stress-strain relationships in the complex upper airway that should present new opportunities for understanding pathogenesis of airway collapse, improving diagnosis and developing treatments.

 

Finite element analysis of blood flow characteristics in a Ventricular Assist Device (VAD)

M.-H. Moosavi, N. Fatouraee, H. Katoozian

Biological Fluid Mechanics Research Laboratory, Biomedical Engineering Faculty, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15914, Iran

Simulation Modelling Practice and Theory 17 (2009) 654–663

Abstract: The replacement or augmentation of failing human organs with artificial devices and systems has been an important element in health care for several decades. There are a lot of geometrical and flow considerations in the artificial organs that are developed to perform in contact with the blood particles. For example, preventing the stagnation, high pressure and shear regions is an important consideration in artificial organ design. In this paper, the geometrical and boundary conditions for the blood flow in the HeartSaver Ventricular Assist Device (VAD) are studied using the numerical solution of the governing equations. In order to provide the interaction between the blood and the elastic diaphragm and between the blood and the inlet/outlet valves, the Fluid-Structural Interaction (FSI) approach is used in this study. Arbitrary Lagrangian–Eulerian (ALE) Finite Element Method (FEM) formulation is used for the numerical solution of the flow domain. Blood and the driving fluid are assumed as isothermal, Newtonian, viscose and incompressible fluids. The numerical solution has provided the required characteristics for the evaluation of the performance of the VAD in contact with the realistic flow conditions. Although they present the formation of wakes in the blood chamber, no stagnation points and high shear rate zones are detected in the blood chamber.

Keywords: Heart valve - Blood flow - Elastic diaphragm - Heart failure - Fluid-Structure Interaction

 

Tunnels And Penstocks of The Nam Theun 2 Hydroelectric Project

N.N. Heidstra

Klohn Crippen Berger Ltd., Vancouver, B.C., Canada

Proc. CDA 2009 Annual Conference, 2009

Abstract: The 1,070 MW Nam Theun 2 Hydroelectric Project is located in central Lao PDR. The tunnels and penstocks convey the power flow from the reservoir impounded by the Nakai Dam, down to the surface powerhouse located at the base of the escarpment on the Nam Kathang River. The gross head of the project is 360 m. The maximum power flow is conveyed through a concrete-lined headrace tunnel, down a concrete-lined pressure shaft, through a steel-lined high pressure tunnel to steel-lined bifurcations where the water is conveyed to four Francis turbines, each 250 MW, and two Pelton turbines, each 35 MW. The headrace tunnel, 1,500m long, was excavated through near horizontally bedded sandstone and siltstone rock at the upstream end which then gradually transformed to steeply dipping sandstone and siltstone rocks. The 270 m deep vertical pressure shaft and the 1,000m long near horizontal, high-pressure steel-lined tunnel were excavated through these steeply dipping sandstone and siltstone rocks. The bifurcations and penstocks are designed for a peak transient pressure of 4.9 MPa. A concrete-lined surge shaft at the downstream end of the headrace tunnel limits the maximum transient pressures in the high-pressure tunnel. The project presented some unique design challenges for the design of the steel-lined high-pressure tunnels, bifurcations, tunnel plugs, hydraulic throttle in the surge shaft and an access door for maintenance in the downstream end of the headrace tunnel.

 

Simulation Analysis for the Engineering of Soft Soil Foundation on the Based of ADINA

D. Meng, Z. Li, Y. Li, J. Huang

Dept of Civil Engineering Hebei Normal University of Science & Technology (HBNUST), Qinhuangdao, 066004, China

Proc. 2009 International Forum on Computer Science-Technology and Applications, 2009

Abstract: It is important geotechnical problem to consolidation of soft soil foundation. Three-dimensional finite element model is established on the based of Biot consolidation theory, the model is loaded and calculated on the based of considering lateral deformation and spatial seepage, elasticplasticity character of soil, construction stage loading progress etc. case study is analyzed to obtain the regular of settlement, lateral displacement and excess hydrostatic pore pressure. The calculation value of finite element method is reasonable to compare with measured data. The finite element method is used to simulate truly every position and step settlement, later displacement and excess hydrostatic pore pressure, feedback calculation value can instruct information construction, control and adjust fill rate of construction, and then settlement of embankment is controlled better. The method can forecast final settlement of embankment more exactly to supply reference of design and construction.

Keywords: soft soil foundation — embankment — finite element method — settlement — lateral displacement

 

Some Experiences from HDR V31.1 and Applied LOCA Analyses on BWR and PWR

K. Nilsson

Onsala Ingenjörsbyrå AB, Kungsbacka, Sweden

Proc. 20th International Conference on Structural Mechanics in Reactor Technology (SMiRT 20), 2009

Abstract: There has been several papers and presentations made about HDR V31.1 simulations the last decade. We performed this simulation the first time in 2001, using ADINA-FSI. ADINA-FSI is the package that includes ADINA(FE), ADINA-CFD and the coupling code. Due to acceptable agreement with experimental data it opened up possibilities to perform applied LOCA analyses using commercial software. In this paper we present three methods to perform simulation of the HDR V31.1 test. The original ADINA-FSI method is companied with the linear acousto-elastic method and a sequential method, that is a combination of the two. From the calculated results none of the methods seems superior to the others, but the computational cost varies greatly. We also present experiences from some of the applied projects that we have performed. The difference between the HDR V31.1 simulation and applied projects is that the latter involves much more sophisticated structural models. In the HDR V31.1 case the structural response was linear. In the applied projects nonlinearities must be included in the structural model. Since the solver time has been increased for the structure, it has forced us to simplify where possible to keep the computational cost at an acceptable level.

 

Estimation of Containment Loads on a 230kV Steel Transmission Line Using Finite Element Model

A. Haldar, M. Veitch, and T. Andrews

Engineering Services Division, Newfoundland and Labrador Hydro, Nalcor Energy, 500 Columbus Drive, St. John’s NL, A1B 4K7, Canada

Proc. ASCE Electrical Transmission and Substation Structures Conference, 20-32, 2009

Abstract: Overhead transmission lines are designed to withstand meteorological loads such as wind, ice, combined wind and ice and static residual loads due to broken conductor and/or ice shedding. A line could be subjected to dynamic overloading when a triggering event is caused by a component failure. In this situation, a shock wave propagates through the system and a redistribution of the force takes place. If the capacity of the remaining system can not support this force redistribution, the line may experience a cascade failure. This paper presents a systematic methodology to model both the static and dynamic behaviors of a line due to conductor breakage using the ADINA (Automatic Dynamic Incremental Nonlinear Analysis) program. Based on the analysis, the extent of a cascade damage/failure zone is estimated and a mitigation approach for correcting the situation is provided.

 

Numerical Simulation of the Aerothermostructural Response of a Composite Solid Rocket Nozzle During Motor Ignition

J.-F. Pitot de la Beaujardiere1, E.V. Morozov2, and Glen Bright1

1 University of KwaZulu-Natal, Durban, KwaZulu-Natal, 4041, South Africa
2 The University of New South Wales, University College, Australian Defence Force Academy, Canberra, ACT, 2600, Australia

Proc. 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2009

Abstract: This paper describes the numerical simulation of the ignition period structural response of a prototype composite solid rocket motor nozzle to a combination of pressure and thermal loading, using a multiphysics finite element approach. Loading conditions characterized by high spatial and temporal resolution were generated by a pair of transient nozzle flow models and applied to associated structural and thermostructural models to obtain individual responses to pressure and thermal loading. To obtain the combined aerothermostructural response of the nozzle, the pressure and thermal stress responses were superimposed. The combined response exhibited quasi-static qualities, with no significant vibratory effects being observed. Hoop and axial stresses were found to be particularly severe in the sub- and transonic nozzle regions, being confined to the highly localized zone of heat penetration, while stresses in the radial direction were generally found to be negligible.

 

Numerical Investigation of the Hemodynamics in Anatomically Realistic Lateral Cerebral Aneurysms

A. Valencia1, J. Munizaga1, R. Rivera2, and E. Bravo2

1 Department of Mechanical Engineering, Universidad de Chile, Santiago, Chile
2 Neuroradiology Department, Instituto de Neurocirugía Asenjo Jose Manuel Infante 553, Santiago, Chile

Proc. 32nd Annual International Conference of the IEEE EMBS, pp. 2616-2621, 2009

Abstract: Hemodynamically induced stress plays an important role in the progression and rupture of cerebral aneurysms. The current work describes computational fluid dynamics (CFD) simulations in anatomically realistic models of cerebral aneurysms. Twenty lateral aneurysms models were investigated. The models were obtained from three-dimensional rotational angiographic imaging data and CFD were studied under the same physiologically representative waveform of inflow. The flow was assumed to be laminar, non-Newtonian, and incompressible. The CFD models were solved with the finite elements package ADINA. Predictions of velocity field and wall shear stress (WSS) on the aneurysms were compared for the different cases. Linear correlations between the WSS on the aneurysm fundus at peak systole for lateral aneurysms with an area index were found.

 

Numerical Simulation of Fluid-Structure Interaction for Wind-induced Dynamic Response of Jinan Yellow River Cable-stayed Bridge in Cantilever State

Y. Zhou1, Q.-L. Zhang1, and Z.-H. Liu2

1 Department of Building Engineering, Tongji University, Shanghai, P.R. China
2 School of Civil Engineering, Shandong University, Jinan, P.R. China

Proc. International Conference on Engineering Computation, DOI 10.1109/ICEC.2009.49:51-54, 2009

Abstract: Long-span bridges are slender, light and flexible large-scale structures. Bridges in the cantilever state are found more susceptible to wind load compared to the bridges in the completed state. The wind-induced dynamic response numerical simulation of fluid-structure interaction of the long span bridge in cantilever state used ADINA is carried out in this paper. The wind-induced dynamic coefficients and the wind pressure distribution coefficients which can be used in the design are also calculated. These analysis provides the evidences for the incremental launching method.

Keywords: long-span bridge — cantilever state — numerical simulation —  incremental launching method — wind induced dynamic response — fluid-structure interaction

 

The Effects of Ice Shedding on a 500 kV Line

A.B. Peabody1 and R. Carrington2

1 Construction Management Department, University of Alaska Anchorage, 3211, Providence Drive, Anchorage AK 99508-4614
2 Power Engineers, Inc., 3900 S. Wadsworth Blvd. Suite 700, Lakewood, CO 80235

Proc. ASCE Electrical Transmission and Substation Structures Conference, 233-244, 2009

Abstract: Ice shedding and the subsequent conductor jump have been of interest to transmission and distribution designers since the early 1900’s. Some of the factors that affect the height of the jump and the transverse movement of the conductor are ice thickness, ice density, phase to phase and span to span patterns of ice loading, the pattern of ice shedding within the span, the wind speed, conductor size and stranding, line angle, structure type, span, and elevation differences between supports. This paper reports the results of finite element dynamic modeling of ice shedding from a 500 kV single circuit tubular steel transmission line. Ten spans of line were modeled including all three phases and two shield wires. The structures and insulators and shield wire hardware were also modeled. All simulations were performed using the commercial finite element program ADINA.

 

Cantilever Dynamics and Nonlinear Effects in Atomic Force Microscopy

A. Raman, R. Reifenberger, J. Melcher, and R. Tung

Noncontact Atomic Force Microscopy, S. Morita et al. (eds.), NanoScience and Technology, 361-395, 2009

Abstract: With increasing efforts to improve resolution and material contrast in dynamic atomic force microscopy (dAFM), it has become important to precisely understand and exploit the mechanical dynamics of the AFM probe as it interacts with samples. Here we provide a broad overview of several topics in this area relevant to both amplitude and frequency modulated (AM and FM) AFM. We discuss threedimensional eigenmodes of cantilever probes and tuning forks, and summarize their nonlinear dynamical interactions with the sample and their operation in liquids. An emphasis is placed on experimental implications of these physical phenomena. We conclude with an outlook of the relevance of these new developments for atomic resolution dAFM and for low-force biological applications.

 

MRI-based biomechanical imaging: initial study on early plaque progression and vessel remodeling

J. Zhenga, D.R. Abendscheina, R. J. Okamotoa, D. Yanga, K.S. McCommisa, B. Misselwitzb, R.J. Groplera, D. Tangc

aMallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63131, USA
bBayer Schering Pharma AG, 13353 Berlin, Germany
cWorcester Polytechnic Institute, MA 01609, USA

Magnetic Resonance Imaging (2009, in press)

Abstract:
The goal of the study is to develop a noninvasive magnetic resonance imaging (MRI)-based biomechanical imaging technique to address biomechanical pathways of atherosclerotic progression and regression in vivo using a 3D fluid-structure interaction (FSI) model. Initial in vivo study was carried out in an early plaque model in pigs that underwent balloon-overstretch injury to the left carotid arteries. Consecutive MRI scans were performed while the pigs were maintained on high cholesterol (progression) or normal chow (regression), with an injection of a plaque-targeted contrast agent, Gadofluorine M. At the end of study, the specimens of carotid arterial segments were dissected and underwent dedicated mechanical testing to determine their material properties. 3D FSI computational model was applied to calculate structure stress and strain distribution. The plaque structure resembles early plaque with thickened intima. Lower maximal flow shear stress correlates with the growth of plaque volume during progression, but not during regression. In contrast, maximal principle structure stress/stain (stress-P1 and strain-P1) were shown to correlate strongly with the change in the plaque dimension during regression, but moderately during progression. This MRI-based biomechanical imaging method may allow for noninvasive dynamic assessment of local hemodynamic forces on the development of atherosclerotic plaques in vivo.

Keywords: MR - Atherosclerosis - Biomechanics - Stress - Stain - Contrast agent

 

Control rod drop analysis by finite element method using fluid–structureinteraction for a pressurized water reactor power plant

K.H. Yoon., J.Y. Kim, K.H. Lee, Y.H. Lee, H.K. Kim

Korea Atomic Energy Research Institute, Daedukdaero 1045 Dukjin-Dong, Yusong-Ku, Daejeon 305-353, Republic of Korea

Nuclear Engineering and Design 239 (2009) 1857–1861

Abstract: The control rod drop analysis is very important for safety analysis. For seismic and loss of coolant accident event, the control rod assemblies shall be capable of traveling from a fully withdrawn position to 90% insertion without any blockage and within specified time and displacement limits. The analysis has been executed by analytical method using in-house code. In this method, several field data are needed. These data are obtained from nuclear, thermal–hydraulic and mechanical design groups, peculiar codes, those work groups need to cooperate together. Following the enhancement of a computer and development of the multi-physics analysis code, a new method for the control rod drop analysis is proposed by finite element method. This analysis model incorporates the structure and fluid parts, termed as a fluid and structure interaction (FSI). Because a control rod is submerged inside a guide tube of a fuel assembly, the FSI boundary condition is applied. In this model, it is assumed that the fluid is incompressible laminar flow. The structures are modeled with the solid elements because there is no deformation due to the fluid flow. The analysis two-dimensional plane model is created in the analysis with considering an axi-symmetric geometry. Therefore, the proposed analysis model will be very simple and the design data from other fields will be unnecessary. The analysis results are compared with those of the in-house code, which have been used for a commercial design. After validation, it is found that the present analysis gives a useful tool in the design of the control rod and fuel assembly.

 

In situ thermal imaging and three-dimensional finite element modeling of tungsten carbide–cobalt during laser deposition

Y. Xionga, W.H. Hofmeisterb, Z. Chengc, J.E. Smugereskyd, E.J. Laverniaa, J.M. Schoenunga

aDepartment of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA
bCenter for Laser Applications, University of Tennessee Space Institute, Tullahoma, TN 37388, USA
cEarth Mechanics Inc., Oakland, CA 94621, USA
dSandia National Laboratories, Livermore, CA 94551, USA

Acta Materialia 57 (2009) 5419–5429

Abstract: Laser deposition is being used for the fabrication of net shapes from a broad range of materials, including tungsten carbide–cobalt (WC–Co) cermets (composites composed of a metallic phase and a hard refractory phase). During deposition, an unusual thermal condition is created for cermets, resulting in rather complex microstructures. To provide a fundamental insight into the evolution of such microstructures, we studied the thermal behavior of WC–Co cermets during laser deposition involving complementary results from in situ high-speed thermal imaging and three-dimensional finite element modeling. The former allowed for the characterization of temperature gradients and cooling rates in the vicinity of the molten pool, whereas the latter allowed for simulation of the entire sample. By combining the two methods, a more robust analysis of the thermal behavior was achieved. The model and the imaging results correlate well with each other and with the alternating sublayers observed in the microstructure.

Keywords: Thermal imaging - Finite element modeling - WC–Co - Laser engineered net shaping

 

Analysis of blood turbulent flow in carotid artery including the effects of mural thrombosis using finite element modeling

1M.Arab-Ghanbari, 2M.M. Khani, 1A. Arefmanesh, 1F.Tabatabai-Ghomshe

1 Islamic Azad University Science and Research Branch, Tehran, Iran
2 Academic Centre for Education, Culture and Research (ACECR), Shaheed Beheshti Medical University Branch (SBMU), Biomedical Engineering Department, Tehran, Iran

American Journal of Applied Sciences 6(2): 337-344, 2009

Abstract: Arterial thrombosis is an extremely significant health problem. As a result of numerous factors involved in such problem, describing the role of hemodynamics in thrombogenesis has been asserted to be one of the most demanding and complicated challenges in biomechanics. An axisymmetric model considering fluid-structure interactions (FSI) was introduced and numerically solved for an artery with a thrombosis to perform flow and stress-strain analysis and investigate the probability of thrombus ruptures leading to embolization. Three models with different thrombus heights were considered and the Navier-Stokes equations were solved for the blood flow as the fluid domain. Results indicated that there are recirculation regions after thrombus bulk, which are susceptible to rethrombosis and stenosis. It was also shown that when the thrombus height increases, the shear stress magnitude on FSI boundary increases and the area near the thrombus peak is too susceptible to rupture. Besides, stress-strain distribution analysis demonstrated that by increasing the thrombus height, the region with high shear stress on the wall declines while the shear stress magnitude of the region under the peak increases up to 4 times. When the thrombus height is low enough (34% of artery diameter), its deformation is larger at the peak and a large area of its downstream side. However, by increasing the thrombus height, there are two sites of large deformation in thrombus at the peak and a small area at the leading edge (in compression site) of thrombus. These regions are vulnerable because of rupture probability.

Keywords: Thrombus - embolism - shear stress - FSI - hemodynamics

 

Theoretical And Experimental Analysis Of The Sheet-Titanium Forming Process

J. Adamus

Czestochowa University of Technology, Institute of Metal Forming, Quality Engineering and Bioengineering, 21, Armii Krajowej Ave, 42-200 Czestochowa, Poland

Archives of Metallurgy and Materials,  54(3):705-709, 2009

Abstract: In the paper sheet-metal forming process, the essential part of modern industry, which enable us to produce the applied drawpiece e.g. in the aircraft, car or building industry, was discussed. Advantages and disadvantages of application of titanium and its alloys in the drawpieces were presented. The numerical simulation results of the stamping process of CP 2 titanium cylindrical cup were given. Material data needed for the numerical simulation, such as: Re, Rm, r-value, hardening coefficient n, forming limit diagram (FLD), were determined experimentally. A special attention was paid to the impact of such parameters as: friction coefficient, tool geometry (corner radius of the die and punch) and holding-down force on the strain distribution in the drawpiece. The simulation results were compared with the experimental ones. The numerical simulation was carried out with the ADINA System based on the finite element methods (MES).

Keywords: sheet-metal forming process – titanium - numerical simulation

 

Analysis Of FIV Characteristics On A Coaxial Double-Tube Type Hot Gas Duct For The VHTR

K. Song1, Y. Kim1, S-C. Park2

1 Korea Atomic Energy Research Institute(KAERI), Daejon, Korea
2 AbleMAX, Inc., Korea

Proc.16th International Conference on Nuclear Engineering (ICONE17), July 12-16, Brussels, Belgium , ICONE17-75007, 2009

Abstract: The Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source of the order of 950Ž for nuclear hydrogen generation, which can produce hydrogen from water or natural gas. A primary hot gas duct (HGD) as a coaxial double-tube type cross vessel is a key component connecting the reactor pressure vessel and the intermediate heat exchanger in a VHTR. In this study, a structural sizing methodology for the primary HGD of a VHTR is suggested in order to modulate a flow-induced vibration (FIV). And as an example, a structural sizing of a horizontal HGD with a coaxial double-tube structure was carried out using the suggested method. These activities include a decision of the geometric dimensions, a selection of the material, and a evaluation of the strength of the coaxial double-tube type cross vessel components. Also in order to compare the FIV characteristics of the proposed design cases, a fluid-structure interaction (FSI) analysis on a quarter carried out using the ADINA code.

Keywords: Nuclear Hydrogen System - Coaxial double-tube type cross vessel - VHTR - Hot Gas Duct (HGD) - Flow-induced Vibration (FIV) - Fluid-structure Interaction (FSI)

 

Experimental and Numerical Investigation of Beetle Flight

T.Q. Le1, D. Byun1, Y.H. Yoo1, J.H. Ko1, H.C. Park2

1 Department of Aerospace and Information Engineering, Konkuk University, Seoul, Korea
2 Department of Technology Fusion, Konkuk University, Seoul, Korea

Proceedings of the 2008 IEEE International Conference on Robotics and Biomimetics, 234-239, 2009

Abstract: We investigate the flight characteristics of the beetle (Allomyrina dichotoma), which has hind wings and elytra, based on the numerical simulation. Flapping kinematics of both the hind wings and the elytra are obtained by visualization in a wind tunnel. One can observe veins and membrane on the hind wings, which allow corrugated patterns on the cross section of the wing along streamwise direction. Therefore, we investigate details of the vein and membrane structures, which is able to be used for modelling the wing for the numerical simulation. The veins thickness ranges from 100 to 1000 micrometers, meanwhile, the thickness of the membrane is around 5 micrometers. Numerical results show that the corrugated cross section wing allows higher aerodynamic performance than the elliptic wing for the same flapping kinematics. The elytra have the positive contribution of vertical force during forward flight, while its effect is not significant when there is no income flow.

Keywords: beetle wing - corrugated section - elytron effect

 

A Study of 2D+ Airfoil FSI Models with Different FSI Approaches

X. Wang1, R. Gordnier2, S. Ji3, and K.J. Bathe4

1 Dept. of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ 07102
2 Air Vehicle Directory, Air Force Research Laboratory, WPAFB, OH 45433
3 ADINA R&D, 71 Elton Ave, Watertown, MA 02472
4 Dept. of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139

Proc. 50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, AIAA 2009-2573, 2009

Abstract: In this paper, we present a study of fully coupled 2D+ FSI model of a deformable airfoil supported at a few points by translational springs. These translational springs represent the third dimension (wing span) structural rigidities (bending and torsion). This 2D+ FSI model is more sophisticated than traditional two-dimensional (2D) model with rigid airfoil and is a simplified version of full fledged three-dimensional (3D) FSI models. The results derived from explicit and implicit immersed methods are compared with those of FSI modeling with adaptive meshing techniques. Although the fluid flow setting is that of a wind tunnel, it is anticipated that with this 2D+ model and proper radiation boundary conditions, it is possible and computational feasible to explore parametric and phase spaces for various design options for external flow environment.

 

Effect of baffles on a partially filled cubic tank: Numerical simulation and experimental validation

M. Eswaran1, U.K. Saha1, D. Maity2

1Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam, India
2Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721 302, West Bengal, India

Computers and Structures,  87:198–205, 2009

Abstract: In this paper, sloshing waves have been analyzed for baffled and un-baffled tanks. Numerical simulations were carried out based on volume of fluid (VOF) techniques with arbitrary-Lagrangian–Eulerian (ALE) formulation which adopts the displacement of solid, the pressure and displacement in the fluid as variables to model the coupled system. The response of the coupled system is obtained by using the well known software ADINA, which offers efficient fully coupled fluid–structure interaction capabilities by finite element method. The results obtained are compared with the available experimental data to demonstrate the reduction of sloshing effects in fluid model.

Keywords: Sloshing - Baffles - Pressure - Displacement - Arbitrary-Lagrangian-Eulerian formulation - Fluid–structure interaction

 

Fluid effects on structural integrity of pipes with an orifice and elbows with a wall-thinned part

Y.-S. Chang1, S.-H. Kim1, H.-So. Chang1, S.-M. Lee1, J.-B. Choi1, Y.-J. Kim1, Y.-H. Choi2

1 School of Mechanical Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Kyonggi-do 440-746, Republic of Korea
2 Korea Institute of Nuclear Safety, 19 Gusong-dong, Yuseong-gu, Daejeon 305-338, Republic of Korea

Journal of Loss Prevention in the Process Industries,  22:854–859, 2009

Abstract: A wall thinning phenomenon caused by erosion, corrosion and flow accelerated corrosion is one of critical issues that should be resolved to assure the structural integrity of nuclear piping systems. The wall thinning is occasionally detected around geometry discontinuities and its excessive amount of volume loss may reach an unanticipated rupture of a piping system. In this research, fluid effects on typical piping components are investigated and a methodology to assess the structural integrity of which has a wall-thinned part is introduced. Parametric three-dimensional fluid–structure interaction and limit load analyses are carried out and, thereby, a new analytical equation reflecting the effects of assorted fluid flow and defect geometry is developed.

Keywords: Computational fluid dynamics analysis - Finite element method - Flow rate – Fluid-structure Interaction analysis - Piping System - Wall Thinning

 

MRI-based biomechanical imaging: initial study on early plaque progression and vessel remodeling

J. Zheng1, D.R. Abendschein1, R.J. Okamoto1, D. Yang1, K.S. McCommis1, B. Misselwitz2, R.J. Gropler1, D. Tang3

1 Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63131, USA
2 Bayer Schering Pharma AG, 13353 Berlin, Germany
3 Worcester Polytechnic Institute, MA 01609, USA

Magnetic Resonance Imaging,  27:1309-1318, 2009

Abstract: The goal of the study is to develop a noninvasive magnetic resonance imaging (MRI)-based biomechanical imaging technique to address biomechanical pathways of atherosclerotic progression and regression in vivo using a 3D fluid-structure interaction (FSI) model. Initial in vivo study was carried out in an early plaque model in pigs that underwent balloon-overstretch injury to the left carotid arteries. Consecutive MRI scans were performed while the pigs were maintained on high cholesterol (progression) or normal chow (regression), with an injection of a plaque-targeted contrast agent, Gadofluorine M. At the end of study, the specimens of carotid arterial segments were dissected and underwent dedicated mechanical testing to determine their material properties. 3D FSI computational model was applied to calculate structure stress and strain distribution. The plaque structure resembles early plaque with thickened intima. Lower maximal flow shear stress correlates with the growth of plaque volume during progression, but not during regression. In contrast, maximal principle structure stress/stain (stress-P1 and strain-P1) were shown to correlate strongly with the change in the plaque dimension during regression, but moderately during progression. This MRI-based biomechanical imaging method may allow for noninvasive dynamic assessment of local hemodynamic forces on the development of atherosclerotic plaques in vivo.

 

Normal and hydrocephalic brain dynamics: the role of reduced cerebrospinal fluid reabsorption in ventricular enlargement

A.A. Linninger,1,3 B. Sweetman,1 and R. Penn2

1 Laboratory for Product and Process Design (LPPD), Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA;
2 Department of Neurosurgery, University of Chicago, Chicago, IL, USA;
3 Department of Bioengineering, University of Illinois at Chicago, Science and Engineering Of.ces (SEO), Room 218 (M/C 063), 851 S Morgan St, Chicago, IL 60607-7052, USA

Annals of Biomedical Engineering, Vol. 37, No. 7, July 2009, pp. 1434–1447

Abstract: CINE phase-contrast MRI (CINE-MRI) was used to measure cerebrospinal fluid (CSF) velocities and flow rates in the brain of six normal subjects and five patients with communicating hydrocephalus. Mathematical brain models were created using the MRI images of normal subjects and hydrocephalic patients. In our model, the effect of pulsatile vascular expansion is responsible for pulsatile CSF flow between the cranial and the spinal subarachnoidal spaces. Simulation results include intracranial pressure gradients, solid stresses and strains, and fluid velocities throughout the cranio-spinal system. Computed velocities agree closely with our in vivo CINE-MRI CSF flow measurements. In addition to normal intracranial dynamics, our model captures the transition to acute communicating hydrocephalus. By increasing the value for reabsorption resistance in the subarachnoid villi, our model predicts that the poroelastic parenchyma matrix will be drained and the ventricles enlarge despite small transmantle pressure gradients during the transitional phase. The poroelastic simulation thus provides a plausible explanation on how reabsorption changes could be responsible for enlargement of the ventricles without large transmantle pressure gradients.

Keywords: Cerebrospinal fluid - Computational fluid dynamics - Fluid–structure interaction - Communicating hydrocephalus - Intracranial pressure

 

Biomechanical comparison of traditional and minimally invasive intradural tumor exposures using finite element analysis

A.T. Ogden1, L. Bresnahan2, J.S. Smith3, R. Natarajan4, R.G. Fessler2

1 Department of Neurological Surgery, Columbia University, The Neurological Institute, 710 W. 168th Street, New York, NY 10032, USA
2 Neurosurgery Academic Offices, Northwestern Memorial Faculty Foundation, Northwestern University, 676 N. St. Clair St. Chicago, IL 60611, USA
3 Department of Neurosurgery, University of Virginia, PO Box 800212, Charlottesville, VA 22908, USA
4 Department of Orthopedic Surgery, Rush University Medical Center, 1653 West Congress Parkway, Suite 764 A, Armour Academic Facility, Chicago, Illinois 60612-3833, USA

Clinical Biomechanics, 24:143–147, 2009

Abstract:
Background: Minimally invasive approaches to intradural pathology have evolved in part in an effort to reduce approach related destabilization of the spine. No biomechanical data exist however evaluating the effects of traditional and minimally invasive exposures.
Methods: A finite element model of the lumbar spine was generated, and a simulated open laminectomy and a modified hemilaminectomy at L4 were performed. Forces were applied to assess changes in flexion, extension, axial rotation, and lateral bending.
Findings: Open laminectomy produced much greater changes in extension, .exion, and axial rotation than the modified hemilaminectomy from the intact. Lateral bending was similarly unaffected for both exposures.
Interpretation: The results suggest that a minimally invasive hemilaminar exposure preserves the structural integrity of the lumbar spine and minimizes alterations to segmental motion postoperatively.

Keywords: Finite element - Laminectomy - Minimally invasive - Spine - Intradural

 

Vibration modes and natural frequencies of saddle form cable nets

I. Vassilopouloua, C.J. Gantesb

aLaboratory of Metal Structures, School of Civil Engineering, National Technical University of Athens, 12, Irinis Avenue, 15121 Pefki, Greece
bLaboratory of Metal Structures, School of Civil Engineering, National Technical University of Athens, 9 Heroon Polytechniou Street, GR-15780 Zografou, Athens, Greece

Computers and Structures (in press, 2009)

Abstract: The objective of this paper is to investigate the dynamic behaviour of cable networks, in terms of their natural frequencies and the corresponding vibration modes. A multi-degree-of-freedom cable net model is assumed, having circular plan view and the shape of a hyperbolic paraboloid surface. The cable supports are considered either rigid or flexible, thus accounting for the deformability of the edge ring. On the basis of numerical analyses, empirical formulae are proposed for the estimation of the linear natural frequencies, taking into account the mechanical and geometrical characteristics of the cable net and the ring, expressed in the form of appropriate non-dimensional parameters. The sequence of the symmetric and antisymmetric modes of the network and the occurrence of modal transition can be predicted in relation to one of these parameters, in analogy to single cables. The differences between a network with rigid cable supports and one with boundary ring, concerning the eigenmodes and the corresponding eigenfrequencies are identified.

Keywords: Cable net - Vibration modes - Modal transition - Deformable edge ring

 



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