ADINA Publications

Page 38

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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Modeling Skid Resistance of Commercial Trucks on Highways

G. P. Ong,1 and T. F. Fwa2

1 School of Civil Engineering, Purdue Univ., 550 Stadium Mall Drive, West Lafayette, IN 47907-2051
2 Dept. of Civil Engineering, National Univ. of Singapore, 10 Kent Ridge Crescent, Republic of Singapore, 119260

Journal of Transportation Engineering, 136(6):510-517, 2010

Abstract: One aspect of commercial truck safety on highways is the risk of skidding. Skidding accidents involving commercial trucks risk injury or death not only to their own occupants but also to other motorists and road users. Past research on truck skidding has been largely limited to empirical accident data analyses or experiments. Few analytical or numerical studies on the mechanisms of truck skidding on highways have been performed. This paper describes the development of a numerical simulation model that can evaluate the skid resistance available to commercial trucks on wet pavements. The model is developed using fundamental structural mechanics and fluid dynamics theories with the consideration of tire-pavement contact and tire-fluid interaction. A validation of the model was performed against experimental data found in the literature. A parametric analysis is presented in this paper to evaluate the effects of the following factors on truck skid resistance: truck speed, magnitude of wheel load, thickness of a water film on a pavement surface, and tire inflation pressure. The practical significance of the simulation model is illustrated with an analysis on the different skid resistance characteristics of trucks when unloaded and fully loaded, respectively.

Author keywords: Skid resistance - Trucks - Fluid-structure interaction - Finite-element method -  Pavement.

 

Analysis of strain state during creeping of polymer materials

A. Gnatowski, P. Palutkiewicz, T. Jaruga

Department of Polymer Processing and Production Management, Czestochowa University of Technology, Al. Armii Krajowej 19c, 42-200 Czêstochowa, Poland

Archives of Materials Science and Engineering, (45)1: 48-55, 2010

Abstract:
Purpose: The numerical simulation of creep of polymer sample was the aim of work. Design/methodology/approach: Creep investigation included polypropylene. The test stand allowed to perform the creep process during bending at the 50 MPa stress level. The numerical analysis of creep model with the uniaxial stress-strain data for concrete mathematical model was done.
Findings: The investigation were helpful to the comparison of the experimental model with the mathematical model. The creep materials defined as user-coded materials can be used in numerical simulation. Research limitations/implications: The accuracy and precision of numerical and experimental research model, and difference of numerical and experimental results was a limitation of the work.
Practical implications: The method and results of examinations can be used practically in numerical simluation.
Originality/value: Traditional, mechanical characteristics received as a result of the investigations under tensile, torsion and compression load are insufficient to predict the behaviour of polymeric materials under the extreme usage conditions as well as during the long time. The approximation results of numerical simulations were presented. The viscoelastic properties as a function of time on the basis of empirical data were presented. The model parameters matching to experimental results.

Keywords: Properties - Analysis and modelling - Creep-resistance - Numerical techniques - Computational material science

 

Three-Dimensional Finite Element Modeling of Static Tire–Pavement Interaction

G. Wang and R. Roque

Department of Civil and Coastal Engineering, University of Florida, 365 Weil Hall,
P.O. Box 116580, Gainesville, FL 32611-6580

Transportation Research Record: Journal of the Transportation Research Board, 2155:158–169, 2010

Abstract: A three-dimensional tire–pavement interaction finite element model (FEM) was developed, calibrated, and validated. First, a threedimensional model of a radial truck tire was developed on the basis of tire characteristics reported by tire manufacturers using the finite element program ADINA. Contact groups between tire and pavement surfaces were then created, thus establishing a complete tire–pavement interaction model. Tire model properties were calibrated on the basis of measured load–deflection curves from one radial truck tire. The model was then validated by comparing predicted contact stresses with measured stresses from the actual radial truck tire. Contact stress analysis was conducted to evaluate tire responses under different levels of normal load and inflation pressure. Excellent correspondence between predicted and measured contact stresses was observed. This work appears to indicate that tire structure and geometry information reported by tire manufacturers, along with measured load–deflection data, can be used to develop three-dimensional models to predict tire–pavement interface stresses and their effects on pavement performance.

 

Modeling of Flow in an In Vitro Aneurysm Model: A Fluid-Structure Interaction Approach

Q. Hao

University of Miami, Coral Gables, Florida

University of Miami  Open Access Dissertations. Paper 508, 2010

Abstract: Flow velocity field, vorticity and circulation and wall shear stresses were simulated by FSI approach under conditions of pulsatile flow in a scale model of the rabbit elastininduced aneurysm. The flow pattern inside the aneurysm sac confirmed the in vitro experimental findings that in diastole time period the flow inside the aneurysm sac is a stable circular clock-wise flow, while in systole time period higher velocity enters into the aneurysm sac and during systole and diastole time period an anti-clock circular flow pattern emerged near the distal neck; in the 3-D aneurysm sac, the kinetic energy per point is about 0.0002 (m2/s2); while in the symmetrical plane of the aneurysm sac, the kinetic energy per point is about 0.00024 (m2/s2). In one cycle, the shape of the intraaneurysmal energy profile is in agreement with the experimental data; The shear stress near the proximal neck experienced higher shear stress (peak value 0.35 Pa) than the distal neck (peak value 0.2 Pa), while in the aneurysm dome, the shear stress is always the lowest (0.0065 Pa). The ratio of shear stresses in the proximal neck vs. distal neck is around 1.75, similar to the experimental findings that the wall shear rate ratio of proximal neck vs. distal neck is 1.5 to 2.

 

Influence of power-law rheology on cell injury during microbubble flows

H. L. Dailey1 and S. N. Ghadiali2

1 Mechanical Engineering and Mechanics, Lehigh University, USA
2 Department of Biomedical Engineering, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, The Ohio State University, USA

Biomechanics and Modeling in Mechanobiology, 9(3):263-279, 2010

Abstract: The reopening of fluid-occluded pulmonary airways generates microbubble flows which impart complex hydrodynamic stresses to the epithelial cells lining airway walls. In this study we used boundary element solutions and finite element techniques to investigate how cell rheology influences the deformation and injury of cells during microbubble flows. An optimized Prony–Dirichlet series was used to model the cells’ power-law rheology (PLR) and results were compared with a Maxwell fluid model. Results indicate that membrane strain and the risk for cell injury decreases with increasing channel height and bubble speed. In addition, the Maxwell and PLR models both indicate that increased viscous damping results in less cellular deformation/injury. However, only the PLR model was consistent with the experimental observation that cell injury is not a function of stress exposure duration. Correlation of our models with experimental observations therefore highlights the importance of using PLR in computational models of cell mechanics/deformation. These computational models also indicate that altering the cell’s viscoelastic properties may be a clinically relevant way to mitigate microbubble-induced cell injury.

Keywords: Power-law cell mechanics - Airway reopening - Ventilator-associated lung injury - Finite element modeling – ADINA


Patterns of Height Changes in Anterior and Posterior Cervical Disc Regions Affects the Contact Loading at Posterior Facets During Moderate and Severe Disc Degeneration: A Poroelastic C5-C6 Finite Element Model Study

Hussain, Mozammil; Natarajan, Raghu N.; An, Howard S.; Andersson, Gunnar B.J.

Spine, Volume 35(18):E873-E881, 2010

Abstract:
Study Design. Biomechanical roles of anterior and posterior portions of the disc (AD and PD, respectively) in governing posterior facets (PF) behavior of a C5-C6 motion segment.
Objective. To understand how height patterns (loss and gain) at AD and PD affects the PF contact loading during moderate and severe grades of cervical disc degeneration (DD).
Summary of Background Data. PF overloading and degeneration after degenerative disc height loss is a clinical concern. This may occur because of a decrease in facet joints space, causing elevated PF contact forces. During a physiologic motion, axial disc height patterns at AD and PD affects the spacing and overlapping of articulating PF surfaces. The question arises as to what percentage of deformation and/or elongation at AD and PD is contributing to a corresponding increase and/or decrease in PF contact loading.
Methods. A poroelastic, three-dimensional finite element model of a C5-C6 segment with a normal (grade I) disc was used after validation. Two degenerated disc models were developed from the normal disc model: moderate (combined effect of Thompson disc grades II and III) and severe (combined effect of Thompson disc grades IV and V). The models were analyzed under compression, flexion, and extension. Height patterns (loss and gain) at AD and PD, and PF loading were calculated for each model.
Results. PF loading increased with PD height loss, and further increased with AD height gain. In moderate DD, PF loading was more affected by PD height loss than AD height gain, whereas in severe DD, it was more affected by AD height gain than PD height loss.
Conclusion. The current study conclusions suggest a possible mechanism for PF loading through loss and gain in the AD and PD heights during moderate and severe grades of DD. Further cervical spine based biomechanical investigations are suggested to verify our findings.

 

Modeling of the fluid structure interaction of a human trachea under different ventilation conditions

M. Malvè1,2, A. Pérez del Palomar1,2, O. Trabelsi1,2, J.L. López-Villalobos2, A. Ginel2, M. Doblaré1,2

1 Universidad de Zaragoza, Spain; CIBER-BBN, Spain and Instituto de Salud Carlos III, Spain
2 Hospital Virgen del Rocío, Seville, Spain

International Communications in Heat and Mass Transfer, In press 2010.

Abstract: This work is focused on the analysis of the response of the tracheal wall to different ventilation conditions. Thus, a finite element model of a human trachea is developed and used to analyze its deformability under normal breathing and mechanical ventilation. The geometry of the trachea is obtained from computed tomography (CT) images of a healthy man. A fluid structure interaction approach is used to analyze the deformation of the wall when the fluid (in this case, air) moves inside the trachea. A structured hexahedral-based grid for the tracheal walls and an unstructured tetrahedral-based mesh with coincident nodes for the fluid are used to perform the simulations with the finite element-based commercial software code (ADINA R & D Inc.). The tracheal wall is modeled as a fiber reinforced hyperelastic solid material in which the anisotropy due to the orientation of the fibers is introduced. Deformation of the tracheal walls is analyzed under different conditions. Normal breathing is performed assuming a sinus shape of the pressure at the inlet and air speed at the outlet based on real data which represent the inspiration and the expiration processes respectively. Mechanical ventilation is simulated as smooth square shape velocity airflow considering positive values of pressure using data from a mechanical ventilation machine. Deformations of the tracheal cartilage rings and of the muscle membrane, as well as the maximum principal stresses in the wall, are analyzed. The results show that, although the deformation and stresses are quite small for both conditions, forced ventilation does not exactly imitate the physiological response of the trachea, since with always positive pressure values the trachea does not collapse during mechanical breathing.

Keywords: Trachea — Finite element method — Fluid–solid interaction — Breath — Mechanical ventilation — Fiber reinforced material


Numerical Modelling of a Shaking Table Test for Soil-Foundation-Superstructure Interaction by Means of a Soil Constitutive Model Implemented in a FEM Code

G. Abate1, M. R. Massimino1, M. Maugeri1, D. Muir Wood2

1 Department of Civil and Environmental Engineering, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
2 Department of Civil Engineering, University of Bristol, Bristol, UK

Geotech Geol Eng, 28:37–59, 2010.

Abstract Dynamic soil-structure interaction (DSSI) plays a fundamental role in many geotechnical and/or structural design situations, as clearly shown by the damage which occurred during several recent earthquakes (Kobe 1995; Koaceli 1999; Chi-Chi 1999; L’Aquila 2009). For a long time civil engineering researchers have devoted increasing attention to this subject. Thanks to their efforts, several technical regulations, such as EC8 (2003), have taken DSSI into account. However, many steps are still necessary in order to increase our knowledge regarding this complex phenomenon, as well as to make all the results achieved known to academics and practitioners. This paper presents the results of a shaking table test performed on a scaled physical model consisting of a 3-D steel frame resting on a bed of sand. The experimental results are compared with the numerical ones obtained using a sophisticated elasto-plastic constitutive model recently implemented in the FEM code utilised. The solution of geotechnical problems requires the use of appropriate constitutive models. Many interesting constitutive models have been developed, but only a few of these have been implemented into commercial numerical codes; which is particularly so when dynamic analyses are required. The described experimental results, as well as the comparison between them and the numerical results, allow interesting considerations to be drawn on dynamic soil-structure interaction and on its numerical simulation.

Keywords: Soil dynamics - Shaking table tests - Finite element analysis - Constitutive models - Soil-structure interaction


3D Finite Element Analyses of Multilayer Dielectric Elastomer Actuators With Metallic Compliant Electrodes for Space Applications

Luca Lampani and Paolo Gaudenzi

University of Rome - La Sapienza, Department of Aerospace and Astronautical Engineering, Via Eudossiana 16/18 00184 Rome, Italy

Journal of Intelligent Material Systems and Structures, 0:1-12, 2010

ABSTRACT: A special actuator device with passive sensing capability based on dielectric elastomer was studied and specialized to be used in space applications. The work illustrates the research project modeling procedure adopted to simulate the mechanical behavior of this material based on a finite-element theory approach. The Mooney-Rivlin’s hyperelastic and Maxwell’s electrostatic models provide the theoretical basis to describe its electromechanic behavior. The validation of the procedure is performed through a numerical-experimental correlation between the response of a prototype of actuator developed by the Risø Danish research center and the 3D finite-element model simulations. An investigation concerning a possible application in the space environment of dielectric elastomer actuators is also presented.

Keywords: EAP – DEA - Dielectric elastomer - Metallic compliant electrode – Actuator - Finite element


Finite Element Analysis of PZT Piezoelectric Ceramics Based on ADINA 

Zhang, C.-S., Guo, C.-J.,  Gao, S.-Q.

Piezoelectricity and Acousto-optics, 32(1): 59-62, 2010

Abstract: Using traditional experiment means on piezoelectric ceramic device has certain limitations due to the complicated boundary conditions and stress situation. In this paper, the finite element model of piezoelectric ceramics in line with the experiment results was established according to piezoelectric structure field and the coupling of the electric field. Deformation of representative PZT piezoelectric ceramics under the voltage was analyzed using finite element analysis software ADINA according to establishing geometric model, defining boundary conditions and materials, coupling calculation. Consistency between simulation results and experimental results was improved and laid the foundation for the realization of the piezoelectric ceramic shapes and vibration control.

Keywords: Boundary conditions - Finite element method - Joining - Lead zirconate titanates - Mathematical analysis - Mathematical models - Piezoelectric ceramics – Piezoelectricity


The Steady-State Temperature Field Analysis of the 3D Rolling Tire Based on Adina FEA Software

Lianxiang Ma, Chuangsheng Wang and Weimin Yang

Faculty of Mechanical and Electrical Engineering, Qingdao University of Science and Technology, China

Advanced Materials Research, (87-88):518-523, 2010

Abstract: Based on the Adina finite element analysis software, 3D axisymmetric finite element analysis model of the 205/75R15 PCR tire was established, the steady temperature field of rolling tire was simulated, and the thermal distribution colored cloud diagram of steady-state temperature field of 3D rolling tire which directly shows the temperature distribution of each section of tire was analyzed to offer certain guidance to the improvement of tire structure and rubber formula.

Keywords:  PCR tire – ADINA finite element analysis software – Temperature field


Motion Changes in Adjacent Segments due to Moderate and Severe Degeneration in C5-C6 Disc: A Poroelastic C3-T1 Finite Element Model Study

Hussain, Mozammil, Natarajan, Raghu N., An, Howard S., Andersson, Gunnar B.J.

Spine, 35(9):939-947, 2010

Abstract:
Study Design. Biomechanics of normal vertebral segments adjacent to a degenerated segment in the cervical spine.
Objective. To test the hypothesis of higher motion changes in the segment immediately inferior to a degenerated segment.
Summary of Background Data. Past research has shown how disc degeneration (DD) affects adjacent segments; however, these studies are conducted only on the lumbar spine or the experimental protocols used are characterized by the presence of degeneration in adjacent segments. The question arises as to how much of the degenerative effect in a particular segment is internal to degeneration at that segment and how much is caused by degeneration at adjacent segments. It would be clinically relevant to analyze biomechanical changes in adjacent segments in the cervical spine by considering DD at only one segment, where adjacent segments remain normal.
Methods. A poroelastic, 3-dimensional finite element model of a normal C3–T1 segment was validated and then used for the degenerative study. Two additional C3–T1 models were developed with moderate and severe degenerative C5–C6 disc grades. Disc geometry and tissue material properties were modified to simulate C5–C6 DD. Intersegmental rotational motions (C4–C5, C5–C6, and C6–C7) for the 3 C3–T1 models were computed under moment loads.
Results. With progressive C5–C6 DD, motion decreased at that segment. At adjacent segments, higher motion changes were observed mainly in flexion/extension. Inferior C6–C7 motion changes were higher than superior C4–C5 motion changes. The inferior C6–C7 motion was affected even when C5–C6 DD was moderate, and it was further affected by severe C5–C6 DD. The superior C4–C7 motion, however, was mostly affected by severe C5–C6 DD.
Conclusion. The hypothesis of higher motion changes in the normal C6–C7 segment immediately inferior to a degenerated C5–C6 segment was found to be true. Future experiments on multisegmental cervical spines are recommended to verify the current data.


Three-Dimensional Finite Element Modeling of Static Tire-Pavement Interaction

Guangming Wang, Reynaldo Roque

Department of Civil and Coastal Engineering, University of Florida, 365 Weil Hall, P. O. Box 116580, Gainesville, FL 32611-6580

Journal of the Transportation Research Board, 2155: 158-169, 2010

Abstract: A three-dimensional tire-pavement interaction finite element model (FEM) was developed, calibrated, and validated. First, a threedimensional model of a radial truck tire was developed on the basis of tire characteristics reported by tire manufacturers using the finite element program ADINA. Contact groups between tire and pavement surfaces were then created, thus establishing a complete tire-pavement interaction model. Tire model properties were calibrated on the basis of measured load-deflection curves from one radial truck tire. The model was then validated by comparing predicted contact stresses with measured stresses from the actual radial truck tire. Contact stress analysis was conducted to evaluate tire responses under different levels of normal load and inflation pressure. Excellent correspondence between predicted and measured contact stresses was observed. This work appears to indicate that tire structure and geometry information reported by tire manufacturers, along with measured load-deflection data, can be used to develop three-dimensional models to predict tire-pavement interface stresses and their effects on pavement performance.


Finite Element Analysis of Eustachian Tube Function in Cleft Palate Infants Based on Histological Reconstructions

Francis Sheer1, J. Douglas Swarts2, and Samir Ghadiali3

1 The Ohio State University
2 Children's Hosptial of Pittsburgh
3 The Ohio State University

The Cleft Palate-Craniofacial Journal, In press, 2010

Abstract: Introduction: The prevalence of otitis media with effusion approaches 100% in infants with Cleft Palate (CP) and disease pathogenesis is believed to be caused by Eustachian tube (ET) dysfunction. Objective: Quantify the functional consequences of ET anatomy in infant CP specimens and identify the relative importance of various tissue biomechanical properties on ET function in CP infants. Methods: Finite element models of the ET's anatomy and physiology were developed using image analysis and 3D reconstruction techniques. Models were developed using histological images of ET structures obtained from 5 infant CP specimens. The models were parameterized and the effect of varying model parameters that included tensor veli palatini and levator veli palatini force, ET cartilage and periluminal mucosal compliance and hamular position on the resistance to airflow through the tubal lumen was determined. Results: Of the evaluated parameters, only the applied tensor veli palatini muscle force and the compliance of the periluminal mucosa and cartilage tissues were significant predictors of the resistance to airflow through the ET during muscle assisted opening. Conclusions: Finite element models of ET function in the CP infant identified tensor veli palatini muscle force as a direct predictor and mucosal/cartilage compliance as an indirect predictor of ET opening during muscle assisted lumen dilations. Hamular position and levator veli palatini force were not found to have an effect on ET function in CP infants.

Keywords: Finite Element Models - Eustachian Tube function - Cleft Palate Infants


Study on Complex Dynamic Pressure Metal Seal in Rotary Vane Steering Gear Based on Fluid Structure Interaction

Su Wenhai

School of Engineering, Northeast Agricultural University, Harbin,150030, China

Advanced Materials Research, (113-116):1606-1609, 2010

Abstract: Cast-iron sealing devices using springs are commonly used in rotary vane steering gear. These devices have good wear resistance, long service life and maintenance-free. Finite Element Analysis of cast-iron sealing device includes contact analysis of metal materials effecting of fluid action. ADINA was used to carry on sealing mechanism of cast-iron sealing device based on taking Fluid-Structure Interaction(FSI) and contact analysis into consideration and the complex dynamic pressure metal seal with ability of automatic compensation is proposed and verified that it can enhance the sealing ability of rotary vane steering gear up to 10MPa and improve power density of steering gear which has important significance to improving controllability of ship.

Keywords: Rotary vane steering gear – Complex seal – Press seal – Fluid-structure interaction - ADINA


The Relationship Between Keloid Growth Pattern and Stretching Tension-Visual Analysis Using the Finite Element Method

Akaishi, S; Akimoto, M; Hyakusoku, H; Ogawa, R

Plastic & Reconstructive Surgery, Volume 125(6):6, 2010

Abstract:
Background: Keloids grow and spread horizontally, like malignant tumors, for reasons that remain unknown. Yet, stretching tension is clearly associated with keloid generation, as keloids tend to occur on high tension sites such as the anterior chest and scapular region. Thus, we analyzed the relationship between keloid growth patterns and stretching tension using a visualized finite element study.
Materials and Methods: Keloids, normal skin, and fat structures were reproduced using DISCUS software. The contours were transferred to ADINA analytical software to rebuild and mesh volumes.
Results: (1) High tension was observed at the edges, and not in the entire region, of stretched keloids. (2) Keloid centers were regions of low tension, which helps to explain the healing that generally occurs in the central regions of keloids. (3) Expansion of a keloid occurred in the direction in which it was pulled. (4) The crab's claw-shaped invasion occurred in response to increased stretching tension. (5) Skin stiffness in the circumference of a keloid was associated with greatly increased tension. (6) Fat hardness and thickness did not influence the amount of tension. (7) Adhesion with subcutaneous hard tissue greatly increased the tension in the keloid.
Conclusion: These stretching results have advanced understanding of keloid formation under various conditions. Our results suggest that stretching tension is an important condition associated with keloid growth.


Pressure Field Analysis of Continuous Rotary Electro-Hydraulic Servo Motor Based on ADINA

Xiao Jing Wang1, Xiao Dong Yang1, Jun Peng Shao1, Ji Hai Jiang2

1 Harbin University of Science and Technology, Mechanical Power Engineering Institute, Harbin 150080, China
2 Harbin Institute of Technology, Institute of Fluid Power Transmission and Control, Harbin 150080, China

Advanced Materials Research, (129-131):1351-1355, 2010

Abstract:In order to improve the low speed stationary of continuous rotary electro-hydraulic servo motor and avoid the pressure impact in the sealed cavity during the oil distribution, based on fluid and solid interaction theory, this paper adopted ADINA to analyze the pressure field distribution of sealed cavity in certain radial and axial gap, the computed model of the motor was established, and the pressure change of sealed cavity under the given dimension of the buffer groove was analyzed. The result shows that the pressure changes stably and buffer groove’s dimension is reasonable, which lays foundation for the structure design and experimental research of large displacement servo motor and improve the low speed performance of continuous rotary electro-hydraulic servo motor.

Keywords: Continuous rotary motor – Low speed – Pressure field analysis – ADINA


Three Dimension Fluid Field of Mixer with Synchronous Rotors

Huiguang Bian1, Cuiwen Fu2 and Dewei Zhang1

1 College of Mechanical Engineering, Qingdao University of Science and Technology
2 Qingdao Brewery Co., Ltd

Advanced Materials Research, (87-88):323-328, 2010

Abstract: The flow field analyzed method about mixer flow in chamber has been introduced, Synchronous rotor three dimension flow field simulation rubber with the Finite Element Analysis is reported. The physical and three dimension Finite Element Method models for synchronous rotors flow field has been built for the first time. Isothermal flow field simulation with synchronous rotor has been made, the pressure field, velocity field and viscosity field had been obtained from numerical simulation. The results showed flow field’s change rule in a circle clearly, which are useful to improve mixer rotor’s structure.

Keywords: Synchronous rotor – Flow field – Boundary conditions – Finite element meshing


Transport-Reaction Model of Mural Thrombogenesis: Comparisons of Mathematical Model Predictions and Results from Baboon Models

Sandra Rugonyi, Erik Tucker, Ulla Marzec, Andras Gruber, and Stephen Hanson

Biomedical Engineering Division, Oregon Health & Science University, M/C CH13B, 3303 SW Bond Ave., Portland, OR 97239, USA

Annals of Biomedical Engineering, 38(8):2660–2675, 2010

Abstract: Thrombogenesis depends on biochemical reactions affected by blood flow dynamics. While mathematical models of mural thrombogenesis provide a means of understanding how blood flow affects thrombus growth, comparisons to experimental data are needed to validate the models and enable prediction of thrombus growth under diverse conditions. In this paper, we present mathematical models of mural thrombogenesis under flow and validation of the models with experimental data collected from a thrombogenic vascular graft segment. The grafts were placed in exteriorized high-flow arteriovenous (AV) shunts in baboons. Radio labeled platelet deposition onto the thrombogenic segment, a marker of thrombus size, and plasma thrombin-antithrombin (TAT) concentration downstream of the graft, a marker of local thrombin generation, were monitored over time. The mathematical model of mural thrombogenesis consisted of transport-reaction equations in which platelets and thrombin were explicitly considered. We found that the transport-reaction model captured the order of magnitude of TAT sampled levels, while calculated rates of platelet deposition agreed well with radioimaging results. Analysis of experimental and modeling data indicates that, at least during part of thrombus growth progression, thrombin generation is in excess and platelet adhesion rates would be sustained even at lower local thrombin concentrations.

Keywords: Thrombus growth - Platelet deposition - Diffusionadvection-reaction - Thrombin generation.


Design of a Pressure Measuring Syringe

Alexander H. Slocum, Jr.1, Samuel C. Duffley1, Jaime Moreu Gamazo1, Adrienne Watral1, Joan E. Spiegel2, Alexander H. Slocum1

1 Department of Mechanical Engineering, MIT, Cambridge, MA 02139
2 Department of Anesthesiology, Beth Israel Deaconess Medical Center, Boston, MA 02215

Proceedings of the 2010 Design of Medical Devices Conference, DMD2010-3891, 2010

Abstract: It is known that excessive pressures within endotracheal tube cuffs and tracheostomy tubes are correlated with serious complications such as tracheal erosions, tracheo-esophageal fistulae and tracheal stenosis. Proper inflation of an endotracheal tube cuff relies upon the use of a manometer to ensure safe pressures. Conventional methods of measuring intra-cuff pressure include the use of a 3-way stopcock and an aneroid manometer, or by simple pilot balloon palpation. Because the former method is cumbersome and expensive, and the latter inaccurate, we have devised an integrated syringe-manometer that allows for simultaneous cuff inflation and visual indication of intra-cuff pressure. The design maintains the feel and look of a traditional syringe with only the internal components altered to accommodate a silicone rubber bellows, of which the load-deflection relationship has been modeled using finite element analysis, and also verified experimentally. A pressure-measuring syringe has been designed, tested, and verified to meet the health-care professional (customer) requirements: the data show a close correlation to the finite-element bellows model (to within +/- 5 percent up to 50% elongation), and the syringe presented here can be used to accurately measure endotracheal tube intra-cuff pressures up to 50 cm H20.


Young’s modulus and density measurements of thin atomic layer deposited films using resonant nanomechanics

B. Ilic,1 S. Krylov,2 and H. G. Craighead1

1 School of Applied and Engineering Physics, Nanobiotechnology Center and Cornell Nanoscale Facility, Cornell University, 212 Clark Hall, Ithaca, New York 14853, USA
2 School of Mechanical Engineering, Tel Aviv University, 69978 Ramat Aviv, Israel

Journal Of Applied Physics, 108, 044317, 2010

Abstract: Material properties of atomic layer deposited (ALD) thin films are of interest for applications ranging from wear resistance to high-k dielectrics in electronic circuits. We demonstrate the ability to simultaneously measure Young’s modulus (E) and density of 21.2–21.5 nanometer ALD hafnia, alumina, and aluminum nitride ultrathin films by observing vibrations of nanomechanical cantilever beams. The nanomechanical structures were fabricated from a 250 nanometer thick single crystal silicon layer with varying length and width ranging from 6 micrometers to 10 micrometers and 45 nanometers to 1 micrometer, respectively. Our approach is based on an optical excitation and interferometric detection of in-plane and out-of plane vibrational spectra of single crystal silicon cantilevers before and after a conformal coating deposition of an ALD thin film. In conjunction with three-dimensional numerical finite element analysis, measurements of resonance carried out prior to the ALD revealed that while the influence of clamping compliance arising from the undercut of the sacrificial layer is significant for wider beams, the effect is less pronounced for both, narrower cantilevers and the in-plane vibrational response. Following the deposition, higher stiffness alumina films (E<ESi) showed an increase in the resonant frequency whereas lower stiffness (E<ESi) hafnia and aluminum nitride films decreased the natural frequency. From the measured spectral response, material properties were extracted using simple expressions for E and the density in terms of measured in-plane and out-of-plane frequencies shifts. The derived model was based on an ideally clamped Euler–Bernoulli beam with effective bending stiffness and effective mass per unit length. In-plane and out-of-plane frequency measurements provided two equations that enabled simultaneous extraction of E and the density. Three-dimensional finite element analysis showed that residual stress, nonideal clamping conditions, and the mismatch in the Poisson’s ratio between the deposited film and the nanomechanical oscillator have minor influence on the determined material properties. Experimental results obtained for the measured films were in excellent agreement with finite element simulations incorporating the geometric undercut caused by release of the suspended structures.


Impact of Wide-Base Single Tires on Pavement Damage

James Greene1, Ulas Toros2, Sungho Kim3, Tom Byron1, and Bouzid Choubane1

1 Florida Department of Transportation, Materials Research Park
2 Applied Research Associates, Inc.
3 University of North Florida; 5007 Northeast 39th Avenue, Gainesville, FL 32609

Transportation Research Record: Journal of the Transportation Research Board, 2155:2–90, 2010.

Abstract: Dual tires have traditionally been used to limit pavement damage by efficiently distributing axle loads over a larger contact area than single tires. However, in recent years, the trucking industry, stating economic and safety benefits, has promoted the use of wide-base single tires. The Super Single tire, an early type of wide-base tire, proved inadequate and induced excessive pavement damage. By contrast, the new generation wide-base tires have contact areas that approach those of dual tires and offer the potential for improved performance. The Florida Department of Transportation investigated the pavement damage potential of four tire types, including a conventional dual tire (11R22.5), a Super Single (425/65R22.5), and two newly designed wide-base single tires (445/50R22.5 and 455/55R22.5 respectively). A controlled accelerated pavement testing program, in addition to theoretical modeling, was performed to determine critical pavement response parameters. Pavement damage was measured in terms of rutting and fatigue cracking (bottom-up or top-down), the predominant distresses in Florida. The investigation revealed that the 455-mm wide-base tire performed as well as the dual tire. By comparison, the 445-mm wide-base tire was shown to create more rut damage on a dense-graded pavement surface and was predicted to create more bottom-up cracking than a dual tire. As expected, the Super Single induced the most damage to the pavement.


Finite Element Analysis for Concrete Damage under Freeze-Thaw Action

M.H Aliabadi, S. Abela, S. Baragetti, M. Guagliano and Han-Seung Lee

College of Engineering, Harbin University, Harbin 150001, China

Key Engineering Materials, Vol. 47-418, pp. 133-136, 2010

Abstract: Freeze-thaw damage is one of the most representative damages in concrete durability. Commonly, freezing and thawing tests are conducted to investigate the freeze-thaw resistance of concrete, and the loss of dynamic modulus of concrete is regarded as the failure criterion. However, the research on the evolution of concrete strength during the damage process is still not enough when subjected to freezing and thawing. In this study, the concrete freeze-thaw deterioration was considered as isotropic elastic damage, and relative variation functions of dynamic modulus and Poisson’s ratio with freeze-thaw cycles were set up. Based on damage mechanics, the Ottosen failure surface model with four parameters was established to indicate the relationship between the concrete freeze-thaw failure surface and freeze-thaw cycles. Then the four-parameter failure surface model was set into ADINA finite element software program for secondary development to investigate the strength properties of concrete component under freeze-thaw action. The relationship between load and deflection of concrete was analyzed and simulated after 0, 25 and 50 freeze-thaw cycles. The simulated and experimental results are basically identical, which demonstrates that this finite element simulation is a feasible way to analyze and evaluate the performance of concrete structures in cold regions.

Keywords: Concrete - Damage Mechanic -  Failure Surface - Finite Element Analysis (FEA) -  Freeze-Thaw


Rolling Control Analysis of Baohua Ro-Ro Ship

Rujian Ma, Meihua Dong, Guixi Li, Menghua Xu

Proc. Second International Conference on Computer Modeling and Simulation, vol. 2, pp.457-460, 2010.

Abstract: A three dimensional solid model of Baohua ro-ro ship in Bohai Bay is built using three dimensional modeling software. The model is then imported into Adina finite element analysis software. In this way, the problem that the finite element model can not approach the actual profile of the ships is solved satisfactory. The modal analysis of the ro-ro ship in Bohai Bay was performed in this paper using Adina finite element analysis software. The rolling modes and the modal frequencies are obtained by the analysis. The cargoes on the ro-ro ship were used for construction of the anti-rolling device to control the rolling movement of the ship. The simulation results indicated that good rolling control effects have been achieved.

Keywords: ro-ro ships -  modal analysis - anti-rolling device - rolling control


Calculation of leakage and friction of combined dynamic seals based on ADINA

Cui, Xiao; Dong, Yan-Liang; Zhao, Ke-Ding

Journal of South China University of Technology, 38(2):95-100, 2010.

Abstract: In order to quantitatively analyze the internal leakage of high-precision electrohydraulic servomotor, a numerical method to solve the oil-film control equation is proposed based on the finite element method. In this method, the contact stress on the seal surface is calculated with the finite element software ADINA; the oil film thickness is obtained by solving the one-dimension Reynolds equation with the inverse method; and the leakage and the friction are also calculated. Then, in order to overcome the difficulty in determining the inflection point of the two-order derivative pressure function, a cubic polynomial is used to fit the pressure at the inlet. Moreover, the effects of O-ring pre-compression ratio, medium pressure, rotor radius, motor velocity and temperature on the leakage and the friction are analyzed. The results indicate that the proposed numerical method is more stable and effective than the conventional iterative method. It is applicable for the calculation of leakage and friction of electrohydraulic servomotor, and it lays a theoretical foundation for the design of elastomeric seals.

Keywords: Electrohydraulic - Finite element method - Friction - Leakage - Mathematical analysis - Mathematical models - Numerical analysis – Seals

 



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