• To Download — Second Edition of the Book "Finite Element Procedures" (4th printing)
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Improved versions will be made available here, from time to time, as the 5th printing, and so on.
"Finite Element Procedures", 2nd Edition (.pdf)
Solutions to exercises in the book "Finite Element Procedures", 2nd Edition, 2014 are given in this manual (.pdf)
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:
Real-time dynamic substructuring testing of viscous seismic protective devices for bridge structures
C. Dion1, N. Bouaanani1, R. Tremblay1, C.-P. Lamarche2, M. Leclerc1
1 Group for Research in Structural Engineering, École Polytechnique de Montréal, Montreal, QC, Canada, H3C 3A7
2 Civil Engineering Department, Université de Sherbrooke, Sherbrooke, QC, Canada, J1K 2R1
Engineering Structures, 33(12):3351-3363, 2011
Abstract: This paper presents a real-time dynamic substructuring (RTDS) test program carried out on bridge structures equipped with two innovative viscous seismic protective devices: a seismic damping unit and a shock transmission unit. In the RTDS tests, the seismic protective units were physically tested in the laboratory using a high performance dynamic actuator imposing, in real time, the displacement time histories obtained from numerical simulations being run in parallel. The integration scheme used in the test program was the Rosenbrock-W variant, and the integration was performed using The MathWorks’ Simulink and XPC target computer environment. The numerical counterpart included the bridge columns and the additional energy dissipation properties. The nonlinear response of these components was accounted for in the numerical models. The tests were run under various ground motions, and the influence of modeling assumptions such as damping and initial stiffness was investigated. Finally, the test results are compared to the predictions from nonlinear dynamic time history analyses performed using commercially available computer programs. The results indicate that simple numerical modeling techniques can lead to accurate prediction of the displacement response of bridge structures equipped with the seismic protective systems studied.
Keywords: Real-time dynamic substructuring testing - seismic isolation - seismic protective systems - viscous dampers - bridge engineering - seismic effects - earthquakes - seismic design - finite elements - nonlinear analysis
Can aspect ratio be used to categorize intra-aneurysmal hemodynamics?—A study of elastase induced aneurysms in rabbit
Z. Zeng1, M.J. Durka1, D.F. Kallmes2, Y.Ding2, A.M. Robertson1
1 Department of Mechanical Engineering and Materials Science, University of Pittsburgh, 3700 O'Hara St., Pittsburgh, PA 15261, USA
2 Department of Radiology, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905, USA
Journal of Biomechanics, 44(16): 2809-2816, 2011
Abstract: Clinical studies suggest that aneurysm aspect ratio (AR) is an important indicator of rupture likelihood. The importance of AR is hypothesized to arise from its influence on intra-aneurysmal hemodynamics. It has been conjectured that slower flow in high AR sacs leads to a cascade of biological activities that weaken the aneurysm wall (Ujiie et al.,1999). However, the connection between AR, hemodynamics and wall weakening has never been proven. Animal models of saccular aneurysms provide a venue for evaluating this conjecture. The focus of this work was to evaluate whether a commonly used elastase induced aneurysm model in rabbits is suitable for a study of this kind from a hemodynamic perspective. In particular, to assess whether hemodynamic factors in low and high AR sacs are statistically different. To achieve this objective, saccular aneurysms were created in 51 rabbits and pulsatile computational fluid dynamics (CFD) studies were performed using rabbit specific inflows. Distinct hemodynamics were found in the low AR (AR<1.8, n=25), and high AR (AR>2.2, n=18) models. A single, stable recirculation zone was present in all low AR aneurysms, whereas a second, transient recirculation zone was also found in the superior aspect of the aneurysm dome for all high AR cases. Aneurysms with AR between 1.8 and 2.2 displayed transitional flow patterns. Differences in values and distributions of hemodynamic parameters were found between low and high AR cases including time averaged wall shear stress, oscillatory shear index, relative residence time and non-dimensional inflow rate. This work lays the foundation for future studies of the dependence of growth and remodeling on AR in the rabbit model and provides a motivation for further studies of the coupling between AR and hemodynamics in human aneurysms.
Keywords: Aneurysm - hemodynamics - aspect ratio - CFD - wall shear stress
Practical dynamic analysis of structures laterally vibrating in contact with water
B. Miquel, N. Bouaanani
Department of Civil, Geological and Mining Engineering, École Polytechnique de Montréal, Montréal, QC, Canada H3C 3A7
Computers & Structures, 89:2195-2210, 2011
Abstract: This paper proposes a practical formulation to investigate the dynamic response of structures laterally vibrating in contact with water on one or both sides. The proposed technique accounts for structure’s flexibility, soil flexibility, varying water levels and various boundary conditions. Simplified procedures are developed for practical assessment of the vibration periods, hydrodynamic loads and seismic response of structure-water systems including higher mode effects. The efficiency of the proposed techniques is validated through examples of structure–water systems with different configurations. We show that the proposed methods give excellent results when compared to more advanced finite element solutions including fluid–structure interaction capabilities.
Keywords: Dynamic analysis - fluid–structure interaction - hydrodynamic loads - vibration periods - simplified formulations - finite elements
Wind-Induced Vibration Responses of Prestressed Double-Layered Spherical Latticed Shells
Z. Zhou, Z. Li, S. Meng, and J. Wu
Key laboratory of RC&PC of Ministry of Education, Southeast University, Nanjing, 210096, China
International Journal of Steel Structures, 11(2):191-202, 2011
Abstract: This paper focuses on the wind-induced vibration response of prestressed double-layered spherical latticed shell (PDSLS) structures by adopting time-domain analysis method. Welch spectrum analysis method is used to make precision evaluation of power spectrum of fluctuating wind speed time history simulated by weighted amplitude wavelet superposition (WAWS) method and linear filtering method of auto-regression (AR) model. Results show that the two methods produce little precision difference, but AR method is far more efficient than WAWS and is more suitable for wind speed simulation of PDSLSs. The effect of various parameters on the wind-induced vibration response of PDSLS structures are comprehensively investigated, including rise-span ratio, span, shell thickness, elastic constraint stiffness, prestress value, with or without cables and cable layout scheme. Results show that rise-span ratio and span are the major factors that affect wind-induced vibration response of PDSLSs. When cables are set, the wind vibration coefficient of nodal vertical displacement becomes smaller and more equally distributed, which demonstrates that PDSLSs are less sensitive to fluctuating wind effect than common latticed shell structures without cables. Finally, based on the envelopment concept and with the maximum dynamic and average wind-induced displacement responses as control indicators, the calculating method for global wind vibration coefficient (GWVC) of PDSLSs is proposed and the value with usual design parameters is given. Meanwhile, when the structure is made static analysis by means of the equivalent static wind load obtained from GWVC, the obtained internal member force response is relatively accordant with the actual response got from time-history analysis, and is a little safer.
Keywords: Prestressed double-layered spherical latticed shell (PDSLS) - wind-induced vibration response - global wind vibration coefficient (GWVC) - time-history analysis - equivalent static wind load
Viscoelastic Damping Technologies: Finite Element Modeling and Application
to Circular Saw Blades
C.M.A. Vasques and L.C. Cardoso
INEGI, Universidade do Porto, Campus da FEUP, R. Dr. Roberto Frias 400, 4200-465 Porto, Portugal
C.M.A. Vasques, J. Dias Rodrigues (eds.), Vibration and Structural Acoustics Analysis, 207-264, 2011
Abstract: A great deal of information on viscoelastic damping technologies, comprising surface mounted or embedded viscoelastic damping treatments, is nowadays available for the practical noise reduction of machinery, in general, and circular saw blades, in particular, for woodworking operations. Among the most efficient and appellative noise reduction techniques for low-noise woodworking circular saw blades demonstrated during the last decades, the use of viscoelastic damping technologies is an interesting possibility which did not receive sufficient attention and dissemination so far. These technologies are analyzed in this chapter in order to gain a preliminary insight into the interest of this noise control solution to further continuing developing more refined and efficient viscoelastic-based noise reduction designs towards the widespread use of low-noise circular saw tooling and industrial practices by woodworking companies. For that purpose, a more comprehensive and tutorial approach to the field is presented in this book chapter. Emphasis is put not also on the specific application to circular saws, which is used to illustrate the interest, applicability and design procedures of such technologies, but also on practical engineering aspects related with the use of computational tools and finite element (FE) modeling software for the mathematical modeling, design and assessment of the efficiency of damping treatments. In particular, different configurations of damping treatments, spatial FE modeling and meshing approaches, mathematical descriptions of viscoelastic frequency-dependent material damping and their implementation into FE frameworks and the use of different solution methods and commercial FE software are discussed.
Numerical simulation reaseach on stress field distribution of coal bed fault structure formation and evolution
H. Jun, Z.P. Jie, C.X. Sheng, and J.F. Xing
Henan Polytechnic University, School of Safety Science and Engineering, Jiaozuo
Jiaozuo 454003, China
Proc. ICAIC 2011, Part I, CCIS 224, 734–740, 2011
Abstract: Using finite element numerical simulation software, ADINA, the formation of a fault structures under the action of tectonic stress was simulated. With the formation of coal-bed fault under a modern tectonic stress field, the destruction conditions of coal and the distribution of stress were simulated. Simulation results show that a tectonic fault structures under the action of the formation of coal seam, in the footwall near the fault plane of the seam and near the bottom of the fault plane of the plate at the top, coal vulnerable to damage; fault structure after the formation of lead in different Direct stress and horizontal stress combinations, are in reverse fault footwall fault plane exist in the vicinity of stress concentration phenomena, reverse fault stress field in the direction of maximum stress from the direction of the main decisions, and normal faults only in the level of stress and vertical stress closer, the stress field in the direction of the major decisions by the vertical stress. Conclusion of the study for the coal and gas outburst prevention and control has important theoretical guidance.
Keywords: Fault - tectonic evolution - numerical simulation - gas outburst
Low pulse pressure with high pulsatile external left ventricular power: Inﬂuence of aortic waves
N.M. Pahlevan1, M. Gharib2
1 Option of Bioengineering, Division of Engineering & Applied Sciences, California Institute of Technology, Pasadena, CA, USA
2 Graduate Aerospace Laboratories, Division of Engineering & Applied Sciences, California Institute of Technology, 1200 East California Blvd., Mail code 205-45, Pasadena, CA 91125, USA
Journal of Biomechanics, 44:2083-2089, 2011
Abstract: Elevated pulse pressure (pp) is considered to be a risk factor for adverse cardiovascular events since it is directly related to an elevated myocardial workload. Information about both pressure and ﬂow wave must be provided to assess hemodynamic complexity and true level of external left ventricular power (ELVP). pp value as a single feature of aortic waves cannot identify true level of ELVP. However, it is generally presumed that ELVP (and consequently LV workload) is positively correlated with pp. This study examined this positive correlation. The aim of this study was to test the hypothesis that aortic wave dynamics can create destructive hemodynamic conditions that increase the ELVP even though pp appears to be normal. To test this hypothesis, a computational model of the aorta with physiological properties was used. A Finite Element Method with ﬂuid–structure interaction was employed to solve the equations of the solid and ﬂuid. The aortic wall was assumed to be elastic and isotropic. The blood was assumed to be an incompressible Newtonian ﬂuid. Simulations were performed for various heart rates (HR) and different aortic compliances while keeping the shape of the inlet ﬂow and peripheral resistance constant. As expected, in most of the cases studied here, higher pp was associated with higher LV power demand. However, for a given cardiac output, mean pressure, and location of total reﬂection site, we have found cases where the above-mentioned trend does not hold. Our results suggest that using pp as a single index can result in an underestimation of the LV power demand under certain conditions related to the altered wave dynamics. Hence, in hypertensive patients, a full analysis of aortic wave dynamics is essential for the prevention and management of left ventricular hypertrophy (LVH) and congestive heart failure.
Keywords: Pulse pressure - Aorta - Wave dynamics - Pulsatile load - Wave intensity
Rotordynamic Analysis for a Turbo-Machine with Fluid-Solid Interaction and Rotation Effects
R. Wang,1,2 Y. Wang,1,2 and X. Guo1,2
1 Department of Engineering Mechanics, Dalian University of Technology, Dalian 116024, China
2 Dynamics and Control, State Key Laboratory of Structural Analysis for Industrial Equipment,
Dalian 116024, China
Mathematical Problems in Engineering, Volume 2011, Article ID 921095, 2011
Abstract: The rotordynamics and fluid dynamics of a turbo-machine considering the effect of fluid-solid interaction (FSI) are numerically investigated using finite element software ADINA. The iterative method is adopted in computation of coupled fields of displacement and fluid. What distinguishes the present study fromprevious ones is the use of ADINA’s rotationalmeshes and the FSI interface that separates the rotor surface from its surrounding fluid. The rotor’s center orbit and frequency response as well as the transient fluid dynamics are obtained with various axial flow speeds. By including real rotating motion of the rotor, this paper presents a better way to solve complicated rotordynamic problems of turbo-machines that are operated in FSI circumstances.
Computational Flow Dynamics of the Severe M1 Stenosis Before and After Stenting
D.C.Suh1, Y.B. Ko3,5, S.-T. Park4, K. Yoon3, O.K. Lim1, J.S. Oh1, Y.G. Jeong1, J.S.Kim2
1 Departments of Radiology and Research Institute of Radiology,
2 Neurology, Asan Medical Center, Seoul, Korea
3 Department of Mechanical Engreering, Dankook University, Yongin, Korea
4 Department of Radiology, Soonchunhyang University Hospital, Seoul, Korea
5 Molding & Forming Technology Team, KITECH, 7-47, Incheon, Korea
Neurointervention, 6:13-16, 2011
Purpose: Computational flow dynamic (CFD) study has not been widely applied in intracranial artery stenosis due to requirement of high resolution in identifying the small intracranial artery. We described a process in CFD study applied to symptomatic severe intracranial (M1) stenosis before and after stenting.
Materials and Methods: Reconstructed 3D angiography in STL format was transferred to Magics (Materialise NV, Leuven, Belgium) for smoothing of vessel surface and trimming of branch vessels and to HyperMesh (Altair Engineering Inc., Auckland, New Zealand) for generating tetra volume mesh from triangular surface-meshed 3D angiogram. Computational analysis of blood flow in the blood vessels was performed using the commercial finite element software ADINA Ver 8.5 (ADINA R & D, Inc., MA). The distribution of wall shear stress (WSS), peak velocity and pressure in a patient was analyzed before and after intracranial stenting.
Results: Computer simulation of wall shear stress, flow velocity and wall pressure before and after stenting could be demonstrated three dimensionally by video mode according to flow vs. time dimension. Such flow model was well correlated with angiographic finding related to maximum degree of stenosis. Change of WSS, peak velocity and pressure at the severe stenosis was demonstrated before and after stenting. There was no WSS after stenting in case without residual stenosis.
Conclusion: Our study revealed that CFD analysis before and after intracranial stenting was feasible despite of limited vessel wall dimension and could reveal change of WSS as well as flow velocity and wall pressure.
Key Words : Cerebral artery – Atherosclerosis - Magnetic resonance imaging (MRI) - Plaque rupture - Fluid structure interaction
A Physiologically Relevant, Simple Outﬂow Boundary Model for Truncated Vasculature
N.M. Pahlevan1, F. Amlani1, M.H. Gorji2, F. Hussain3, and M. Gharib1
1 Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, CA, USA;
2 Institute of Fluid Dynamics, ETH Zurich, Zurich, Switzerland; and
3 Department of Mechanical Engineering, University of Houston, Houston, TX, USA
Annals of Biomedical Engineering, 3(5):1470–1481, 2011
Abstract: A realistic outﬂow boundary condition model for pulsatile ﬂow in a compliant vessel is studied by taking into account physiological effects: compliance, resistance, and wave reﬂection of the downstream vasculature. The new model extends the computational domain with an elastic tube terminated in a rigid contraction. The contraction ratio, the length, and elasticity of the terminal tube can be adjusted to represent effects of the truncated vasculature. Using the wave intensity analysis method, we apply the model to the test cases of a straight vessel and the aorta and ﬁnd good agreement with the physiological characteristics of blood ﬂow and pressure. The model is suitable for cardiac transient (non-periodic) events and easily employed using so-called
black box software.
Keywords: Blood ﬂow - Fluid-structure interaction – Arterial wave reﬂection - Computer modeling
High-resolution Magnetic Resonance Imaging-based Biomechanical Stress Analysis of Carotid Atheroma: A Comparison of Single Transient Ischaemic Attack, Recurrent Transient Ischaemic Attacks, Nondisabling Stroke and Asymptomatic Patient Groups
U. Sadat1,2, Z. Teng1, V.E. Young1, M.J. Graves1, M.E. Gaunt2, J.H. Gillard1
1 University Department of Radiology, University of Cambridge, Cambridge, UK
2 Cambridge Vascular Unit, Addenbrooke’s Hospital, Cambridge, UK
Eur J Vasc Endovasc Surg.,41(1):83-90, 2011
Background: Vulnerable carotid plaques are associated with cerebrovascular ischaemic events. High-resolution magnetic resonance (MR) imaging not only allows the morphological assessment of such plaques, but also provides geometrical data, which can be used for biomechanical stress analysis. We assess its utility to assess the plaque stress profiles of symptomatic (transient ischaemic attack (TIA) and non-disabling stroke) and asymptomatic patients.
Methods: A total of 70 consecutive patients with confirmed underlying carotid artery disease underwent carotid MR imaging of their carotid artery in a 1.5-T MR system using a standard carotid atheroma imaging protocol. MR images were manually segmented for different plaque components and used for biomechanical stress analysis. The maximum critical stress (M-CStress) for various clinical groups was determined and compared.
Results: M-CStress of symptomatic plaques (n = 45) was significantly higher than for asymptomatic plaques (n = 25) (median (interquartile range (IQR): 275 kPa (190-390) vs. 165 kPa (120-200), p = 0.0001)). Within the symptomatic group, no M-CStress differences were present between the TIA (n = 30) and stroke (n = 15) patients (260 kPa (190-370) vs. 295 kPa (200-510), p = 0.31). Within the TIA patient cohort, those who had presented with recurrent TIAs (n = 6) had significantly higher stresses than patients who had suffered a single episode (n = 24) (425 kPa (285-580) vs. 250 kPa (180-310), p = 0.001).
Keywords: Carotid plaque - Atherosclerosis - Magnetic resonance imaging - Biomechanical stresses - Stroke - Transient ischaemic attack
Generalised beam theory-based ﬁnite elements for elastoplastic thin-walled metal members
Rodrigo Goncalves1, Dinar Camotim2
1 UNIC, Departamento de Engenharia Civil, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
2 ICIST/IST, Departamento de Engenharia Civil e Arquitectura, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
Thin-Walled Structures, In press 2011
Abstract: This paper addresses the formulation and validation of GBT-based beam ﬁnite elements, intended to analyse the physically non-linear (plastic zone) behaviour of thin-walled metal members. Both stressbased and stress resultant-based elastoplastic formulations are developed. The stress-based formulation is generally more accurate, but the stress resultant-based formulation, which employs the Ilyushin yield function, leads to signiﬁcant computational savings, namely (i) numeric integration in the through-thickness direction is not required and (ii) constraints to the stress resultant and workconjugate strain ﬁeld, typical of linear elastic GBT-type formulations, are straightforwardly enforced. The choice of interpolation functions and the cross-section discretization procedure are also discussed. In order to illustrate the application, provide validation and demonstrate the capabilities of the proposed ﬁnite elements, several numerical results are presented and discussed. These results are compared with those obtained with standard 2D-solid and shell ﬁnite element analyses.
Keywords: Generalised beam theory (GBT) - Thin-walled structures - Beam ﬁnite elements - Elastoplastic materials
In vivo MRI-based 3D Mechanical Stress-Strain Profiles of Carotid Plaques with Juxtaluminal Plaque Haemorrhage: An Exploratory Study for the Mechanism of Subsequent Cerebrovascular Events
Z. Teng1, U. Sadat1,2,Y. Huang1, V.E. Young1, M.J. Grave1, J. Lu3, J.H. Gillard1
1 University Department of Radiology, University of Cambridge, Level 5, Box 218, Addenbrooke’s Hospital, Hills Rd., Cambridge CB2 0QQ, UK
2 Department of Surgery, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
3 Radiology Division, Changhai Hospital, Shanghai, China
Eur J Vasc Endovasc Surg, In press 2011
Objectives: Atherosclerotic plaque features, such as fibrous cap erosion, ulceration and rupture and presence of haemorrhage in carotid plaque are two important characteristics associated with subsequent cerebrovascular events and juxtaluminal haemorrhage/thrombus (JLH/T) indicates these two high-risk characteristics. This study aims to investigate the association between JLH/T and subsequent events in patients suffering from transient ischaemic attack (TIA). Three-dimensional mechanical analysis was employed to represent the critical mechanical stress (P-CStress) and stretch (P-CStretch) within the plaque.
Methods: Fifty TIA patients with mild-to-moderate carotid stenosis (30-69%) underwent highresolution magnetic resonance imaging (MRI) within 72 h of the acute event and eight were excluded from the analysis due to various reasons. A total of 21 patients were found to have JLH/T in the carotid plaque and 21 did not (N-JLH/T). During a 2-year follow-up period, 11 (52.4%) patients in the JLH/T group experienced recurrent events and none in the N-JLH/T group. Three-dimensional plaque structure was reconstructed based on the in vivo MRI for the mechanical analysis.
Results: P-CStress of both groups was comparable (N-JLH/T: 174.45 +/- 63.96 kPa vs. JLH/T: 212.60 +/- 89.54 kPa; p Z 0.120), but P-CStretch of JLH/T was significantly bigger than that of N-JLH/T (N-JLH/T: 1.21 +/- 0.08 vs. JLH/T: 2.10 +/- 0.53; p < 0.0001). Moreover, there were much bigger variations in stress and stretch of the JLH/T group during one cardiac cycle than in those of N-JLH/T group.