ADINA Publications

Page 28

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:

(latest on Page 43)
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A Finite Element Analysis of Local Oscillometric Blood Pressure Measurements

P.A. Shaltis1, A.T. Reisner2, H. H. Asada1

1 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
2 Massachusetts General Hospital Boston, MA 02114, USA

Proc 29th Annual Int Conf IEEE EMBS, 355-358, 2007

Abstract: Traditional circumferential oscillometric blood pressure measurements are based on a complex interplay between the perturbed underlying artery and the surrounding tissue. When there is a balance in pressures acting across the arterial wall, the pulsation amplitude is expected to be a maximum. The purpose of this study was to examine the change in pulsation amplitude for a given pressure resulting from a focally applied compression. A non-linear, twodimensional finite element analysis of an average fingerbase was used to determine the overall pressure distributions within the finger as well as to compare the feasibility of the focally applied oscillometric approach for blood pressure (BP) measurements. We found that the focally applied pressure appears to lead to only a slight underestimation of the BP (1.5 mmHg). Furthermore, it does not significantly inhibit global bloodflow and should therefore be an acceptable method for long-term blood pressure monitoring.

 

Residual stress effect on degradation of polyimide under simulated hypervelocity space debris and atomic oxygen

R. Verke1,2, E. Grossman1, I. Gouzman1, N. Eliaz2

1 Space Environment Section, Soreq NRC, Yavne 81800, Israel
2 Department of Solid Mechanics, Materials and Systems, Tel-Aviv University, Ramat Aviv, Tel-Aviv 69978, Israel

Polymer, 48:19-24, 2007

Abstract: Polyimides are used as the outer layer of thermal control insulation blankets covering most of the external spacecraft surfaces that are exposed to space environment. The combined effect of ground simulated hypervelocity space debris impacts and atomic oxygen (AO) on the fracture of polyimide films was studied. A laser-driven flyer system was used to accelerate aluminum flyers to impact velocities of up to 3 km/s. The impacted films were exposed to an RF plasma source, which was used to simulate the effect of AO in the low Earth orbit. Scanning electron microscopy and atomic force microscopy were used to characterize the fracture and surface morphology. When exposed to oxygen RF plasma, the impacted polyimide film revealed a large increase in the erosion rate, the damage being characterized mainly by the formation of new holes. This effect is explained by the formation of residual stresses due to the impact and enhancement of oxygen diffusivity and accumulation. A complementary experiment, in which a stressed polyimide was exposed to RF plasma, supports this model. This study demonstrates a synergistic effect of the space environment components on polymers’ degradation, which is essential for understanding the potential hazards of ultrahigh velocity impacts and AO erosion for completing a successful spacecraft mission.

Keywords: Polyimide - Atomic oxygen - Space debris

 

Utilizing Pushover Analysis for Seismic Performance of Steel Bridge Structures

T.A. Ballard, A.Krimotat, R. Mutobe

SC Solutions, Inc., 3211 Scott Blvd., Santa Clara, CA 95050, 2007

Abstract: Seismic retrofit of steel bridges requires more advanced analysis techniques to determine capacities and predict inelastic performance parameters. Normal engineering analysis practice assumes linear-elastic behavior for structural members, which fails to reliably account for re-distribution of forces due to member non-linear behavior and dissipation of energy due to material yielding. The performance criteria for the 1958 Carquinez Strait Bridges is “no-collapse” which implies that structural members may yield, exhibiting both material and geometric nonlinear behavior, provided that sufficient reserve strength and ductility remains to prevent the structure from collapsing. With increasing construction costs and tighter budgets, a key component in removing overconservatism in the final retrofit design and effecting a cost-efficient, yet sound design solution, is to take a more rigorous approach to the structural analysis. Advances in technology for computer hardware and software permitted the 1958 Carquinez Strait Bridge seismic retrofit project team to perform a non-linear dynamic analysis for the main span structure in order to better characterize the behavior of the bridge and quantify the damage the structure might sustain during a large seismic event. This paper discusses the non-linear pushover analysis, which was a key component of the non-linear dynamic analysis and of the overall retrofit design effort for the bridge. The development of the material properties for the steel members is discussed and results of the as-built, prototype retrofit and final retrofit pushover analyses for one of the bridge towers is used to examine the procedures and rationale implemented to perform a performance based analysis and design.

 

Wet-Pavement Hydroplaning Risk and Skid Resistance: Modeling

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, 133(10):590-598, 2007

Abstract: The risk of hydroplaning and reduction of skid resistance are two major safety concerns in wet weathering traffic operations on highways and runways. The writers earlier developed an analytical computer model to simulate the phenomenon of hydroplaning. The simulation of wet-pavement skid resistance is analytically a more complex problem to handle than hydroplaning simulation. The present paper adopts a more elaborate theoretical approach and proposes an improved analytical computer model to simulate hydroplaning as well as the reduction of wet-pavement skid resistance as the sliding wheel speed increases. The theoretical formulation and development of a three-dimensional finite-element model based on solid mechanics and fluid dynamics is presented. The computed hydroplaning speeds by the proposed model were analyzed and verified against the well-known experimentally derived NASA hydroplaning-speed equation. The analysis confirmed that the NASA equation is a special case of a general solution, and that it is applicable only to a specific range of tire footprint aspect ratios. An analysis of the decreasing trend of wet-pavement skid resistance with vehicle speed and its validation against measured experimental data will be the subject of another paper.

Keywords: Computational fluid dynamics technique - Finite elements - Fluid-structure interaction - Skid resistance -  Pavements – Risk

 

Skid Resistance And Hydroplaning Analysis Of Rib Truck Tires

C. Cao

Department Of Civil And Environmental Engineering, National University Of Singapore

Master’s Thesis, 2007

Abstract: The scope of the thesis consists of the following parts: to develop a FSI numerical model suitable for hydroplaning and skid resistance of rib truck tires; to evaluate the hydroplaning performance of wide-base truck tires under different operation conditions; and to simulate and predict skid resistance of rib truck tires under different operation conditions.

Compliant biomechanics of abdominal aortic aneurysms: A fluid–structure interaction study

Christine M. Scotti, Ender A. Finol

Biomedical Engineering Department, Institute for Complex Engineered Systems, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA, 15213, USA

Computers and Structures 85 (2007) 1097–1113

Abstract: Abdominal aortic aneurysm (AAA) rupture is believed to represent the culmination of a complex mechanism partially driven by the forces exerted along the lumen. In the present investigation, partially and fully coupled fluid–structure interaction (FSI) computations of three patient-specific AAA models are presented. This work advances previous FSI studies by including the iliac bifurcation and localized intraluminal thrombus. Among the patient models analyzed in this investigation, the FSI resulted in a maximum wall stress that varied 3–25% from the stress obtained with computational solid stress methods, demonstrating the importance of modeling blood flow for the assessment of AAA wall mechanics.

Keywords: Abdominal aortic aneurysm - Fluid–structure interaction - Wall stress - Intraluminal thrombus

 

Burj Dubai: Engineering The World’s Tallest Building

W.F. Baker, D.S. Korista and L.C. Novak

Skidmore, Owings & Merrill LLP, Chicago, Illinois, USA

Struct. Design Tall Spec. Build., 16:361-375, 2007

Abstract: As with all super-tall projects, diffi cult structural engineering problems needed to be addressed and resolved. This paper presents the approach to the structural system for the Burj Dubai Tower.

 

Monitoring Of Long-Term Deformations Of Ataturk Rockfill Dam By Calibrated Finite Element Model

S. Malla, M. Wieland and R. Straubhaar

Pöyry Energy Ltd., Hardturmstrasse 161, CH-8037 Zurich, Switzerland

Proc. ICOLD International Commission on Large Dams 75th Annual Meeting, St. Petersburg 2007, 2007

Abstract: The 170 m high Ataturk rockfill dam was completed in 1990 and dam safety has been monitored continuously since then. The monitoring system comprises visual inspections, comprehensive geodetic surveys, and various types of sensors and instruments. For the safety monitoring, a detailed finite element (FE) model of a representative section of the dam was created, in which slip movements were allowed at the core-filter and filter-rockfill interfaces. The elasto-plastic model was assumed for the main dam materials. The material properties were determined based on laboratory tests, published data, and engineering judgment. Two basic load cases were considered, i.e. (i) dead load and (ii) water load. The geodetically measured dam displacements could be fitted satisfactorily with a linear combination, with time-dependent coefficients, of the computed displacements due to the gravity and water loads obtained from the FE analysis. It was further shown that the history of the timedependent coefficients, which represented the creep-type post-construction deformations of the dam, could be fitted with asymptotic exponential trends. This model was calibrated based on displacements measured until the year 2000. The calibrated model was used to predict the dam displacements for a period of ten years. The dam displacements measured since 2001 show good agreement with the predicted values. This comparison of measured and predicted displacements is most beneficial for the safety monitoring of the Ataturk dam. The calibrated dam model allows an insight into the processes in the dam body that lead to the observed deformations of the dam surface. The possible effect of the increase of the reservoir water level on the dam deformations could also be estimated using the calibrated dam model.

 

Stability analysis of a borehole wall during horizontal directional drilling

J.X. Wang and R.L. Sterling

Trenchless Technology Center, Louisiana Tech University, Ruston, LA 71272, United States

Tunnelling and Underground Space Technology, 22:5-6:620-632, 2007

Abstract: In this paper, numerical simulation strategies are proposed and numerical analyses are performed to investigate the stability of a borehole wall during horizontal directional drilling in loose sand with an emphasis on the role of the filter cake in borehole stability. Two computational scenarios, one in the absence of a filter cake and one with the presence of a filter cake in a borehole wall, are investigated by considering both deep and shallow borehole situations. In the case where no filter cake is formed, the soil–drilling fluid interaction analysis shows that the effective pressure on soil particles will quickly decrease to zero even at a low drilling fluid pressure because of the rapid drainage of the drilling fluids into the loose sands. This conforms to the classical liquefaction criterion, indicating that static (flow) liquefaction-based soil crumbling and sloughing will occur even at a very low drilling fluid pressure if an effective filter cake is not formed. Soil’s permeability effect on pore pressure and the transition to a steady flow are also studied. In the second scenario in which a filter cake is formed, the hydraulic fracture failures around the bores are investigated, which are caused by the expansion of the yielding zones. The yield zone sizes and critical drilling fluid pressures at the moment of hydraulic fracturing failure are calculated from the finite element analyses and the closed-form solution, which is based on classical plasticity theories. The critical fluid pressures from the finite element analyses and the closed-form solutions are very close, but there is a large discrepancy between the yield zone sizes.

Keywords: Stability analysis — Horizontal directional drilling — Finite element method — Filter cake — Soil and drilling fluid coupling — Critical drilling fluid pressure

 

Hydrodynamics of torsional probes for atomic force microscopy in liquids

S. Basak1, A. Beyder2, C. Spagnoli,2 A. Raman3, and F.Sachs4

1 School of Mechanical Engineering and the Birck Nanotechnology Center, Purdue University, 585 Purdue Mall, West Lafayette, Indiana 47907, USA
2 Department of Physiology and Biophysics, University at Buffalo, State University of New York, 3535 Main Street, Buffalo, New York 14214, USA
3 School of Mechanical Engineering and the Birck Nanotechnology Center, Purdue University, 585 Purdue Mall, West Lafayette, Indiana 47907, USA
4 Department of Physiology and Biophysics, University

Journal Of Applied Physics, 102:024914-1 to 024914-7, 2007

Abstract: Improving the force resolution of atomic force microscopy for soft samples in liquid requires soft cantilevers with reduced hydrodynamic cross section. Single and dual axis torsion levers (Beyder and Sachs, 2006) are an attractive technology. They have reduced area and reduced drift due to the symmetric support (Beyder et al., 2006) can add a second dimension using two independent axes. Here we investigate the hydrodynamics of these probes using three-dimensional transient fluid-structure interaction models with comparison to the experimental data. The computed Q factors and wet/dry resonance frequencies of different modes compare well with experimental measurements indicating that continuum viscous hydrodynamics can be used effectively to predict probe performance. The modeling further explores cross-axis hydrodynamic coupling and the influence of a nearby sample plane to provide guidance on approach algorithms and the possibilities of parametric detection.

 

Wet-pavement hydroplaning risk and skid resistance: Modeling

G. P. Ong1 and T. F. Fwa2

1Postdoctoral Research Associate, School of Civil Engineering, Purdue Univ., 550 Stadium Mall Dr., West Lafayette, IN 47907-2051

2Professor, Dept. of Civil Engineering, National Univ. of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Republic of Singapore

Journal Of Transportation Engineering, October 2007

Abstract: The risk of hydroplaning and reduction of skid resistance are two major safety concerns in wet weathering traffic operations on highways and runways. The writers earlier developed an analytical computer model to simulate the phenomenon of hydroplaning. The simulation of wet-pavement skid resistance is analytically a more complex problem to handle than hydroplaning simulation. The present paper adopts a more elaborate theoretical approach and proposes an improved analytical computer model to simulate hydroplaning as well as the reduction of wet-pavement skid resistance as the sliding wheel speed increases. The theoretical formulation and development of a three-dimensional finite-element model based on solid mechanics and fluid dynamics is presented. The computed hydroplaning speeds by the proposed model were analyzed and verified against the well-known experimentally derived NASA hydroplaning-speed equation. The analysis confirmed that the NASA equation is a special case of a general solution, and that it is applicable only to a specific range of tire footprint aspect ratios. An analysis of the decreasing trend of wet-pavement skid resistance with vehicle speed and its validation against measured experimental data will be the subject of another paper.

Keywords: Computational fluid dynamics technique - Finite elements - Fluid-structure interaction – Skid resistance - Pavements - Risk

 

Dynamics of the human upper airway: On the development of a three-dimensional computational model

J. Wang1, G.A. Tetlow1, A.D. Lucey1, J.J. Armstrong2, M.S. Leigh2, A. Paduch2, D.D. Sampson2, J.H.Walsh3, P.R. Eastwood3, D.R. Hillman3, S. Harrison4

1 Fluid Dynamics Research Group, Curtin University of Technology, Australia
2 Optical+Biomedical Engineering Laboratory, University of Western Australia, Australia
3 West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Australia,
4 Mechanical Engineering, University of Western Australia, Australia

IFMBE Proceedings, Vol. 14/5:3442-3452, 2007

Abstract: The advances reported herein form part of a larger project that has as its objective the development of a full flow-structure-interaction model of the human upper airway. Here we first briefly report on a two-dimensional (saggital section) model built using published CT-scan geometric data. For the development of our three-dimensional capability, we use the unique data captured in vivo by an endoscopic optical technique that we have developed. This measurement system, described as anatomical optical coherence tomography (aOCT), allows quantitative real-time imaging of the internal anatomy of the human upper airway with minimal invasiveness. Moreover, the system permits motions of the internal geometry at a fixed location to be recorded. The aOCT data set is insufficient by itself to construct a complete geometry because only the polar coordinates are obtained in a local reference frame. Accordingly, the locus described by the endoscope, in which the aOCT is housed, is obtained by orthogonal CT scans. The combination of CT scans and aOCT measurements then provides the required geometric information for the construction of the computational model. Results of a twodimensional model show how the soft palate responds to the mean-flow variations of the breathing cycle. For the threedimensional work, the key results of this paper rest in the reconstruction of the time-dependent geometry of the upper airway, the first time that this has been accomplished using direct internally-based measurement.

Keywords: Upper-airway anatomy — Sleep apnea — Upperairway modeling — CAD modeling — Image processing

 

 

Drag Reduction on Micro-Structured Super-hydrophobic Surface

Doyoung Byun1, Saputra2 and Hoon Cheol Park2

1Artificial Muscle Research Center, Department of Aerospace Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, 143-701 Seoul, Korea
2Artificial Muscle Research Center, Department of Advanced Technology Fusion, Konkuk University,1 Hwayang-dong, Gwangjin-gu, 143-701 Seoul, Korea

Proceedings of the 2006 IEEE International Conference on Robotics and Biomimetics

Abstract: This paper presents numerical and experimental investigation of drag reduction on the micro-engineered surface, which is inspired by nature. Computational simulation has been performed to examine the flow characteristics on both smooth and rough surfaces, and an experimental investigation is conducted by using artificial super-hydrophobic surface fabricated by MEMS fabrication technique. The artificial surface is made of silicon wafer, where micro-structured with hydrophobic properties has been successfully mimicked. Effect of rough surface has been numerically examined by measuring the velocity profile and skin friction coefficient (cf) at grooves wall, which are compared with those of smooth surface. Unlike smooth surface, it is verified that the vortices flow are generated inside the valley of groove and affected the skin friction coefficient along the grooves wall to be small inside grooves valley region. Because of this small skin friction, the total drag may be reduced by the rough surface. The effect of grooves structure is also demonstrated by varying the shape and aspect ratio of grooves. This effect shows that high aspect ratio of groove generates different vortex shape inside the grooves valley and sudden increment of velocity profile near the wall was existed. The local skin friction value of grooves with aspect ratio 1 and 2 shows almost the same level, meanwhile the grooves with aspect ratio 8 gives lower skin friction value.

Keywords: Drag reduction - super-hydrophobic surface - MEMS fabrication - CFD simulation

 

Analysis of changes in bone cement damping factor and its effect on bone load

P. Postawaa, A. Szarek b

aDepartment of Polymer Processing and Production Management, Czestochowa University of Technology, Al. Armii Krajowej 19c, 42-200 Czestochowa, Poland
bInstitute of Metal Working and Forming, Quality Engineering and Bioengineering, Czestochowa University of Technology, Al. Armii Krajowej 21, 42-200 Czestochowa, Poland

AMME Journal of Achievements in Materials and Manufacturing Engineering, Vol. 23, No. 1, July 2007

Abstract: The article presents the results of simulations and material-related investigations for bone cement used for alloplasty of hip joint. Mechanical properties of bone cements are of key importance for a successful surgery and further use of the joint as well as its behaviour during complex load which appears during patient’s walk.

Keywords: Biomaterials - Mechanical properties - Numerical techniques - DMTA method

 

Experimental and numerical evaluation of the impact of folds on the pressure rating of CIPP liners

A. Jaganathana, E. Alloucha, M. Baumertb

aTrenchless Technology Center, Ruston, LA, USA
bDepartment of Civil Engineering, Louisiana Tech University, USA

Tunnelling and Underground Space Technology 22 (2007) 666–678

Abstract: A cast-iron water main rehabilitated with a thermoplastic structural liner can be viewed as a hybrid pipe. Depending on the degree of corrosion of the host pipe, stress levels carried by the liner may vary signi.cantly. Several limit states can be developed for a liner-pipe structural system. One such state is related to the presence of a longitudinal fold in a cured-in-place-pipe (CIPP) liner that coincides with gaps in the host pipe’s wall. This paper reports the results of an experimental testing and numerical modeling study undertaken to evaluate the impact of a longitudinal fold on the ability of a CIPP liner to resist internal pressures when there are signi.cant gaps present in the host pipe’s wall. Two 3-D numerical models were constructed and validated using physical testing and the analytical solutions provided in ASTM F 2207-02. The results of a parametric study performed to estimate the stress concentration in the fold as a function of the fold’s geometry and level of applied internal pressure are also reported. An empirical approach is proposed as a basis for a guideline regarding the maximum allowable oversizing of CIPP liners in pressure pipes.

Keywords: Water pipes - Longitudinal fold - CIPP liner - Geometric imperfection - QC criteria

 

Linear isolation of stainless steel legged thin-walled tanks

Jose L. Almazan, Fernando A. Cerda, Juan C. De la Llera, Diego Lopez-Garcia

Department of Structural and Geotechnical Engineering, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, Santiago, Chile

Engineering Structures 29 (2007) 1596–1611

Abstract: Because of the booming wine industry in some seismic countries such as the US, Chile and Argentina, seismic protection of wine storage systems is of practical importance. In this study, the dynamic response of thin-walled legged wine tanks with seismic isolation is investigated. Linear fluid–structure interaction has been considered in the analyses performed with SAT-LAB and ADINA and two choices for the seismic isolation system have been evaluated: (i) a traditional lateral isolation system (LAI), and (ii) a vertical-rocking isolation system (VRI). As far as the authors know, the latter has not been considered in previous studies, and results show that it is a viable alternative for legged tanks. Moreover, all isolation devices have been designed considering the space limitations that are inherent to the implementation of these systems in practice. Results obtained for a suite of records and different structures have shown that both types of isolation lead to response reductions of the tank stresses. The reduction ranges from 20% to 79% for the LAI models and 31%–91% for the VRI, relative to the case without isolation. These promising results have implications in the selection of the thickness of the wall and the overall dimensions of the tank.

Keywords: Stainless-steel tanks - Wine tanks - Thin-walled tanks - Fluid–structure interaction - Seismic isolation - Lateral and vertical-rocking isolation - Response reduction

 

Experimental and numerical study on tuned liquid dampers for controlling earthquake response of jacket offshore platform

Qiao Jina, Xin Lia, Ning Suna, Jing Zhoua, Jiong Guanb

aState Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China
bIKM Ocean Design, Postboks 99, 4064 Stavanger, Norway

Marine Structures 20 (2007) 238–254

Abstract: Earthquake loading has to be considered when the offshore platform is constructed in active fault zone. Tuned liquid dampers (TLD) have been proposed to control the dynamic response of structures. Liquid sloshing experiments on cylinder tank show the sloshing happens more seriously when the frequency of external excitation is close to the fundamental sloshing frequency of liquid. Lumped mass method is employed to numerically analyze the controlling earthquake effect on TLD. Based on TLDs the feasibility to control earthquake response of jacket platform is studied and applied to CB32A oil tank platform. Using extra TLDs in CB32A to control the seismic response of the platform is researched by the model test and numerical simulation. Lumped mass method can simulate the behavior of TLD during earthquake very well and gives close numerical results compared with those from model experiments. It has been found that the ratio of the fundamental sloshing frequency of liquid to the natural frequency of platform is the key factor to control earthquake response. The larger ratio of water-mass to platform-mass is also useful to reduce vibration as well.

Keywords: Jacket platform - Tuned liquid dampers - Sloshing - Earthquake response - Vibration control - Model test - Numerical simulation

 

Stability analysis of a borehole wall during horizontal directional drilling

X. Wang, R.L. Sterling

Trenchless Technology Center, Louisiana Tech University, Ruston, LA 71272, United States

Tunnelling and Underground Space Technology 22 (2007) 620–632

Abstract: In this paper, numerical simulation strategies are proposed and numerical analyses are performed to investigate the stability of a borehole wall during horizontal directional drilling in loose sand with an emphasis on the role of the filter cake in borehole stability. Two computational scenarios, one in the absence of a filter cake and one with the presence of a filter cake in a borehole wall, are investigated
by considering both deep and shallow borehole situations. In the case where no filter cake is formed, the soil–drilling fluid interaction analysis shows that the effective pressure on soil particles will quickly decrease to zero even at a low drilling fluid pressure because of the rapid drainage of the drilling fluids into the loose sands. This conforms to the classical liquefaction criterion, indicating that static (flow) liquefaction-based soil crumbling and sloughing will occur even at a very low drilling fluid pressure if an effective filter cake is not formed. Soil’s permeability effect on pore pressure and the transition to a steady flow are also studied. In the second scenario in which a filter cake is formed, the hydraulic fracture failures around the bores are investigated, which are caused by the expansion of the yielding zones. The yield zone sizes and critical drilling fluid pressures at the moment of hydraulic fracturing failure are calculated from the finite element analyses and the closed-form solution, which is based on classical plasticity theories. The critical fluid pressures from the finite element analyses and the closed-form solutions are very close, but there is a large discrepancy between the yield zone sizes.

Keywords: Stability analysis - Horizontal directional drilling - Finite element method - Filter cake - Soil and drilling fluid coupling - Critical drilling fluid pressure

 

Fabric-formed concrete

Robert Schmitz

R.P Schmitz Consulting Engineers, Brookfield, WI

Structure Magazine, July 2007

Abstract: Concrete members have traditionally been cast using a rigid framework. Although recently, ACI Committee 334 has introduced construction of shells using inflated forms. Straightforward methods of analysis and design are available for the traditionally cast concrete member — be it a concrete floor, beam, wall or column member. To date, no design procedures or methods to predict the deflected shape of a fabric cast concrete member have been developed. This article, adapted from a paper presented at the 17th Analysis & Computation Specialty Conference held in conjunction with the 2006 Structures Congress, introduces a design procedure that allows one to design a fabric cast concrete wall panel.

 

Finite element modeling of blood flow-induced mechanical forces in the outflow tract of chick embryonic hearts

Aiping Liua, Sandra Rugonyia, Jeffrey O. Pentecostb, Kent L. Thornburgb

aDepartment of Biomedical Engineering, Oregon Health & Science University, 3303 SW Bond Avenue, Mail Code: CH13B, Portland, OR 97239, United States
bHeart Research Center, Oregon Health & Science University, Portland, OR 97239, United States

Computers and Structures 85 (2007) 727–738

Abstract: Forces exerted by the flow of blood on the walls of the embryonic heart, such as pressures and shear stresses, in.uence heart development; and deviations from normal flow conditions lead to structural defects. To better understand the effect of blood flow on the development of the heart, it is important to characterize the hemodynamic forces that act on the heart walls. Other studies have attempted to
quantify such forces. However, shear stresses on the heart walls cannot be measured directly, and quanti.cations using in vivo velocity measurements are not yet accurate due to the challenges of obtaining velocity profiles near the moving walls of a beating heart. The objective of this work is to quantify hemodynamic forces on the heart wall of chick embryos that are about 3.5 days of incubation (stage HH21), using a combination of physiological data and finite element (FE) models. We focused on the heart outflow tract (OFT) since at this stage the development of the OFT is very sensitive to hemodynamic forces. In this paper, we present a three-dimensional dynamic FE model that is based on a series of ultrasound images of the OFT. Simulations of the FE model, performed for the ventricular ejection phase of the cardiac cycle, showed a complex blood flow pattern within the OFT and gave temporal and spatial distributions of shear stresses and pressures at the inner surface of the OFT wall.

Keywords: Heart development - Heart outflow tract (OFT) - Embryonic heart - Congenital heart disease - Hemodynamic forces - Biomechanical model - Embryology

 

Effects of implant design parameters on fluid convection, potentiating third-body debris ingress into the bearing surface during THA impingement /subluxation

Hannah J. Lundberga,b, Douglas R. Pedersena,b, Thomas E. Baera, Marian Mustec, John J. Callaghana,b,d, Thomas D. Browna,b

aDepartment of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA 52242, USA
bBiomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
cIIHR-Hydroscience and Engineering, University of Iowa, Iowa City, IA 52242, USA
dVeterans Administration Medical Center, Iowa City, IA 52242, USA

Journal of Biomechanics 40 (2007) 1676–1685

Abstract: Aseptic loosening from polyethylene wear debris is the leading cause of failure for metal-on-polyethylene total hip implants. Third-body debris ingress to the bearing space results in femoral head roughening and acceleration of polyethylene wear. How third-body particles manage to enter the bearing space between the closely conforming articulating surfaces of the joint is not well understood. We hypothesize that one such mechanism is from convective fluid transport during subluxation of the total hip joint. To test this hypothesis, a three-dimensional (3D) computational fluid dynamics (CFD) model was developed and validated, to quantify fluid ingress into the bearing space during a leg-cross subluxation event. The results indicated that extra-articular joint fluid could be drawn nearly to the pole of the cup with even very small separations of the femoral head (<0.60 mm). Debris suspended near the equator of the cup at the site of maximum fluid velocity just before the subluxation began could be transported to within 11 degrees from the cup pole. Larger head diameters resulted in increased fluid velocity at all sites around the entrance to the gap compared to smaller head sizes, with fluid velocity being greatest along the anterosuperolateral cup edge, for all head sizes. Fluid pathlines indicated that suspended debris would reach similar angular positions in the bearing space regardless of head size. Increased inset of the femoral head into the acetabular cup resulted both in higher fluid velocity and in transport of third-body debris further into the bearing space.

Keywords: Wear - Third body - Total hip arthroplasty - Computational model

 

Investigation of temperature and stress fields in laser cladded coatings

Rafal Jendrzejewski, Gerard Sliwinski

Photophysics and Laser Lab., Polish Academy of Sciences, The Szewalski Institute of Fluid-Flow Machinery, Fiszera 14, 80-231 Gdansk, Poland

Applied Surface Science, 254 (2007) 921–925

Abstract: Temporal and spatial distributions of temperature and strain–stress have been modelled and investigated experimentally for the laser cladding process. The model corresponded to experimental conditions where the multilayer protective coatings were prepared by direct laser cladding of stellite SF6 powder on X10Cr13 chromium steel by means of a 1.2 kW CO2 laser. For calculations the effect of base preheating, temperature dependent material properties, and also influence of time-break between cladding of the consecutive layers were taken into account. The calculated temperature fields indicated good bonding of the substrate and coating, which was in agreement with the micro-analytical test results. A decrease of the number of microcracks in the coating with an increase of substrate preheating temperature was concluded from stress calculations and confirmed in the experiment. Moreover, an increase of the cracking susceptibility with an increase of the time delay between cladding of the consecutive layers was evidenced by modelling. The best technological results were obtained for the case of single-layer coatings prepared on a preheated substrate and for higher coating thickness required the processing of consecutive layers with a possibly short time delay is advisable due

Keywords: Strain–stress field - Laser cladding - Protective coating - Cracking

 

Microcantilever mechanics in flowing viscous fluids

Anirban Jana1,2, Arvind Raman1,2, Babita Dhayal1,3, Steven L. Tripp1,3, and Ronald G. Reifenberger1,3

1School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907
2Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907
3Department of Physics, Purdue University, West Lafayette, Indiana 47907

Appl. Phys. Lett. 90, 114110  (2007)

Abstract: Microcantilevers are often deployed in flowing fluids to measure local flow velocities or to detect rapidly the nanomechanical binding of trace quantities of target analytes. The authors investigate the flow-induced mechanics of microcantilevers by deriving a semianalytical theoretical model for the nanoscale deflections of an elastic microcantilever due to a laminar viscous flow incident upon it. Conversely, the model allows for the estimation of the local flow velocities based on measured microcantilever deflection. Careful experiments performed on silicon microcantilevers in flowing nitrogen confirm the theoretical predictions up to a critical flow rate, beyond which unsteady flow-induced vibrations are seen to occur.

 

Poro-elastic finite element model to predict the failure progression in a lumbar disc due to cyclic loading

R.N. Natarajana,b, J.R. Williamsa, S.A. Lavenderc, G.B.J. Anderssona

aDepartment of Orthopedic Surgery, Rush University Medical Center, 1653 West Congress Parkway, 764A Armour Academic Facility,
Chicago, IL 60612, United States
bDepartment of Bioengineering, Science and Engineering O.ces, Room 218, 851 S. Morgan Street (M/C 063), Chicago, IL 60607, United States
cDepartment of Industrial, Welding and Systems Engineering, 1971 Neil Avenue, Room 210, Columbus, Ohio 43210, United States

Computers and Structures 85 (2007) 1142–1151

Abstract: There is a steady and concentrated e.ort to improve finite element models of the spinal motion segment that can simulate various clinical situations accurately. Recent developments in the area of poro-elastic finite element models including fluid structure interaction with in the disc have made it possible to understand the relationship between disc failure mechanisms and time dependent loading. The development of such a finite element model is presented here and used to predict the failure progression in a lumbar disc due to a physiologically relevant cyclic loading. This will help to understand how repetitive lifting is of importance in the development of back injuries.

Keywords: Finite element model - Cyclic loading - Lumbar motion segment - Circadian variation in height - Poro-elasticity - Disc degeneration

 

Flow-Structure Interaction in the Upper Airway: Motions of a Cantilevered Flexible Plate in Channel Flow with Flexible Walls

J. Wang, G.A. Tetlow and A.D. Lucey

Fluid Dynamics Research Group, Curtin University of Technology, Western Australia, 6845 AUSTRALIA

Proc. 16th Australasian Fluid Mechanics Conference, 2007

Abstract: The present work seeks to elucidate the flow-structure dynamics of the upper airway so that improved clinical strategies for the alleviation of snoring and sleep apnoea can be developed and applied on an evidence basis. Analogue computational modelling, appropriately related to the anatomically correct system, is used. Hitherto, such modelling has been confined to flow in a rigidchannel to study flutter of the soft palate. Clinical evidence suggests that apneic events can involve combined motions and interactions of the soft palate and flexible walls of the pharynx. We model a flexible cantilevered plate (the soft-palate) mounted in a channel of square cross-section (the pharynx), the downstream side walls of which are flexible to capture deformation in airway collapse. Upstream of the flexible plate is a rigid plate (the hard palate) that spans the channel to permit airflow to be drawn from two inlets (oral and nasal). The commercial FSI software ADINA is used to construct the model and undertake the three-dimensional investigation. Results show that motions of the soft-palate have little effect on the deformation of the side walls. However, the amplitude and frequency of soft-palate vibrations are found to be strongly dependent upon side-wall stiffness and, hence, dynamics.

 

Reconstruction and analysis of three-dimensional finite element model of human middle ear

G.P. Zhang, A.X. Wu, P. Dai , D. Y.Han, J.S. Chen, Z.L. Han, Y.Q. Li

Department of Otorhinolaryngology, Head and Neck Surgery, Third Affiliated Hospital of Sun Yet-sen University, Guangzhou 510630, China.

Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi (2007) 42(5):357-361

Abstract:
OBJECTIVE: To reconstruct a finite element model of human middle ear and measure characteristic dimensions of this model and calculate the mass properties of the ossicles.
METHODS: The proposed method starts with the histologic section preparation of human temporal bone. Through tracing outlines of the middle ear components on the sections in AutoCAD2005, a set of exterior contours of the components is obtained. The three-dimensional solid model of middle ear, including tympanic membrane, ossicular bones, middle ear suspensory ligaments/muscles, are reconstructed using these contours in Unigraphics (UG). To prepare for finite element analysis (FEA) of the middle ear, all surfaces of the solid model are translated into ADINA, a commercial FE model package. Based on these surfaces, FE meshes of the middle ear are created, and material properties and boundaries are set up. The characteristic dimensions of this model are measured and the mass properties of the ossicles are calculated to confirm the accuracy of the geometric model constructed following the proposed method.
RESULTS: The three-dimensional finite element model of the human middle ear that included tympanic membrane, ossicular bones and middle ear suspensory ligaments/muscles was reconstructed. The accuracy of this geometric model was confirmed with the outcome of the characteristic dimensions of this model and the mass properties of the ossicles.
CONCLUSIONS: The proposed method not only provides an effective, convenient, economic, accurate way to reconstruct the three dimensional finite element model of human middle, but also provides a detailed knowledge of middle ear geometry that is required for finite element analysis.

 

Seismic response of cement-soil mixing pile composite foundation with time-history analysis

Yang, Zhi-Hua (Institute of Geotechnical Engineering, Dalian University of Technology); Yang, Qing; Kong, Gang-Qiang; Luan, Mao-Tian Source: Yantu Lixue/Rock and Soil Mechanics, v 29, n 3, March, 2008, p 805-810 Language: Chinese

ISSN: 1000-7598

Publisher: Academia Sinica

Abstract: The cement-soil mixing pile composite foundations are getting more and more application to construction engineering. However, the research on their response under dynamic loading, especially under earthquake loading, is quite limited. Now, the seismic response analysis in the time domain is performed with ADINA program, considering the interactions among soil, foundation and the superstructure. Based on these analyses, some conclusions which may be useful for a seismic design of this type composite foundations are drawn. (15 refs.)

Keywords:  Foundations  -  Cements  -  Constitutive models  -  Earthquake resistance  -  Finite element method  -  Mathematical models  -  Seismic response  -  Soil mechanics

Secondary  Keywords:  Cement soil mixing pile  -  Composite foundation  -  Earthquake load  -  Dynamic interaction  -  Time history analysis  -  ADINA  -  Construction engineering




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