To Enrich Life
(Sample pages here)
Following are more than 700 publications — that we know of — with reference to the use of ADINA. Since there are numerous papers published in renowned journals, we can only give here a selection. 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:
Web Buckling Prevention in Built-up Shear Links
M. Rosignoli1 and C. Rosignoli2
1 Dr. Marco Rosignoli, Dr.Ing., P.E., Chief Bridge Engineer, HNTB Corp., 600 108th Avenue NE, Suite 900, Bellevue, WA 98004
2 Chiara Rosignoli, Dr.Ing., Via Rava 15, I-43100 Parma, Italy
Proc. The Sixth National Seismic Conference on Bridges & Highways, Charleston, South Carolina, USA, 2008
Abstract: Passive steel links yielding in shear are being used as seismic energy dissipation systems for retrofit of existing bridges and the design of new long spans and cable-stayed bridges. Five built-up shear links with different web stiffening solutions were designed for bridge applications, and their 3D solid finite-element models were analyzed with ADINA. The dimensions of the links and the grades of steel were selected so as to permit a rapid use of the data gathered with this research in the design of twin-blade piers for long span bridges and towers of cable-stayed bridges in high seismicity regions. The objectives of the research were to investigate the plastic strain demands on built-up shear links, the buckling behavior, the degradation in the hysteretic loops generated by out-of-plane deformations in the web, and the improvements achievable with the use of horizontal web stiffeners in lieu of more conventional vertical stiffeners. A finite-element formulation reproducing the linear response of links to service loads and the inelastic shear-yielding response as resulting from load testing was also implemented for global analysis of long span bridges with SAP 2000.
Novel developments and findings for the safety assessment of earthquake-excited dam-reservoir systems
N. Bouaanani1, F. Lu1, C. Perrault1, M.A. Chagnon1, and I. Gogoi2
1 Department. of Civil, Geological and Mining Engineering, École Polytechnique de Montréal, Canada
2 Lecturer, Department of Civil Engineering, Assam Engineering Institute, Guwahati, India
Proc. of the 14th World Conference on Earthquake Engineering, Beijing, China, 2008
Abstract: Many dams worldwide have been in service over 50 years and are located in high seismicity areas. The initial seismic design of these critical structures was generally conducted using simplified methods that do not fully take into account of the dynamic nature of earthquake excitation and the complex fluid-structure interaction. Although significant work has been done to evaluate the seismic response of dams, there is still a need to improve commonly used simplified methods and to accurately assess the efficiency of more sophisticated ones. The first part of this paper proposes new practical formulas to evaluate earthquake-induced hydrodynamic loading on concrete dams. This original technique generalizes the classical added-mass formulation by including the effects of dam flexibility and reservoir bottom absorption. Frequency response functions of hydrodynamic pressures within the reservoir are compared to analytical solutions. It is shown that the method accurately predicts hydrodynamic loads and that it can be easily implemented in a computer program or a spreadsheet. The second part of the paper investigates finite element modeling aspects to assess the seismic performance of concrete dams. Several finite element models of dam-reservoir systems with various dimensions are used to conduct frequency and time domain analyses. Potential-based fluid elements and viscous boundary conditions are validated against analytical solutions and they are shown to perform adequately for practical seismic analysis of dam-reservoir systems.Keywords: Dam safety - hydrodynamic loading - seismic effects - numerical modeling
Dynamic behaviour of twin single-span ballasted railway viaducts — Field measurements and modal identification
C. Rebeloa, L. Simoes da Silvaa, C. Rigueirob, M. Pirchera
aISISE, Civil Engineering Department, University of Coimbra, Portugal
bISISE, Civil Engineering Department, Polytechnic Institute of Castelo Branco, Portugal
Engineering Structures 30 (2008) 2460–2469
Abstract: This paper presents the results of experimental measurements on a number of existing small to medium single span ballasted railway bridges in Austria. These bridges were selected for dynamic field measurements following a preliminary numerical evaluation that identified very high vertical accelerations. From the dynamic measurements it was possible to conclude that: (i) the damping due to friction between ballast particles and the friction in the supports plays an important role in the evaluation of maximum accelerations and (ii) the first natural frequencies of the bridges vary according to the amplitude of vibration, that is, increasing vibration amplitudes correspond to a decrease of the first natural frequency in a consistent way for all investigated bridges. Calibrated FE models for these bridges confirmed the experimental conclusions.
Keywords: Railway viaducts - Vibration - Ballast - Measurements
Wet-pavement hydroplaning risk and skid resistance: Analysis
T. F. Fwa1 and G. P. Ong2
1Professor, Dept. of Civil Engineering, National Univ. of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Republic of Singapore
2Postdoctoral Research Associate, School of Civil Engineering, Purdue Univ., 550 Stadium Mall Dr., West Lafayette, IN 47907-2051
Journal Of Transportation Engineering, May 2008
Abstract: This paper presents a numerical simulation of the wet-pavement skid resistance reduction process as the sliding speed of a locked wheel increases. The development of the three-dimensional finite-element model used for the simulation is presented in a companion paper. The proposed model is able to simulate tire-fluid-pavement interaction of a sliding locked wheel on a wet pavement for hydroplaning and skid resistance analysis. The verification of its ability to predict hydroplaning speed is found in the companion paper. In this paper, the validation of the predicted wet pavement skid resistance at different sliding wheel speeds is made by comparing it with measured values from six different experiments conducted by past researchers. A very good match is found between the computed values by the proposed numerical model and the measured data. The analytical model offers a useful tool to predict the magnitude of wetpavement skid resistance at any given locked-wheel sliding speed. As an analytical model, it also produces valuable information on the deterioration mechanism of skid resistance. It shows quantitatively the following changes as the sliding speed of a locked wheel increases:
a progressively reduced contact area; a progressively increased fluid uplift force under the tire; and the corresponding decreases in the normal contact force at the tire-pavement interface.
Keywords: Computational fluid dynamics technique - Pavements - Finite element method - Fluid-structure interaction - Skid resistance - Risk management
Design of circular steel arches with hollow circular cross-sections according to EC3
C.A. Dimopoulos, C.J. Gantes
Department of Civil Engineering, National Technical University of Athens, Greece
Journal of Constructional Steel Research 64 (2008) 1077–1085
Abstract: Design of either pin-ended or fixed circular steel arches with hollow circular cross-sections subjected to a uniformly distributed vertical load along the horizontal projection of the entire arch with the aid of the EC3 provisions is discussed. Appropriate modification factors are proposed that should be included in EC3 interaction equations, to improve their accuracy for the design of such arches.
Keywords: Design - Circular arches - Fixed - Pin-ended - EC3 - Steel - Strength
Nonlinear in-plane behavior of circular steel arches with hollow circular cross-section
C.A. Dimopoulos, C.J. Gantes
Department of Civil Engineering, National Technical University of Athens, Greece
Journal of Constructional Steel Research 64 (2008) 1436–1445
Abstract: In this work the nonlinear in-plane behavior of circular arches with hollow circular cross-section is investigated. The influence of a number of design parameters, such as the boundary conditions, the rise-to-span ratio, and the included angle on the strength is presented. Moreover, the effect of other behavior factors, such as the geometrical and material nonlinearities and the initial imperfections, is investigated. A criterion for the prediction of the type of nonlinear behavior of arches is given, and a formula for the determination of the nonlinear buckling load is proposed. It is found that the effect of initial imperfections on the strength depends largely on the arch slenderness and the imperfection magnitude in the case of shallow arches. When arches are deep this dependence becomes less significant. The effect of geometrical nonlinearity depends significantly on the shallowness and the slenderness of the arches. Stocky arches are less influenced by the rise-to-span ratio than slender ones. The effect of boundary conditions depends significantly on the shallowness of arches and the arch slenderness. The reduction of strength is larger in slender arches than in stocky ones.
Keywords: Circular arches - Nonlinear buckling - Strengths - Steel - Snap-through - Bifurcation
Ultimate shear strength of long web panels
Sung C. Leea, Doo S. Leea, Chai H. Yoob
aDepartment of Civil and Environmental Engineering, Dongguk University, Seoul 135-700, Republic of Korea
bDepartment of Civil Engineering, Auburn University, Auburn, AL 36849-5337, USA
Journal of Constructional Steel Research 64 (2008) 1357–1365
Abstract: Both the Basler model and the Rockey model developed during the early 1960s and 1970s predict reasonably well the postbuckling strength of plate girder web panels subjected to pure shear for panels having an aspect ratio (stiffener spacing/web depth) less than or equal to 1.5. The accuracy of these models deviates significantly when applied to panels with an aspect ratio equal to or greater than 3.0. The majority of all steel structures in the world have been designed and built based on these two major theories or their derivatives that recognize the reserve strength afforded by tension field action in the postbuckling stage. However, no single theory has ever emerged that explains the seemingly elusive stress distributions present in web panels during postbuckling until Yoo and Lee shed light on the true mechanics of web panel postbuckling behavior in shear. This paper revisits the validity of an arbitrary limit imposed by Basler on the maximum aspect ratio of a transversely stiffened web panel and develops a new method of predicting the ultimate shear strength of web panels with high aspect ratios.
Keywords: Aspect ratio - Buckling - Finite element analysis - Flange - Shear strength - Tension field action - Transverse stiffener - Web panels
Vibration, buckling and collapse of ovaloid toroidal tanks
H.J. Zhan, D. Redekop
Department of Mechanical Engineering, University of Ottawa, Canada K1N 6N5
Thin-Walled Structures 46 (2008) 380–389
Abstract: A shell-theory finite element analysis is carried out for toroidal tanks with ovaloid cross-section. The analysis serves to determine the natural frequencies, and the buckling and collapse pressures. A variety of support conditions are considered, including lines of support at the inner and outer equator of the tank. For validation, comparison is made with previously published results for stress, vibration, and buckling of elliptical toroidal shells. Finally, a parametric study is carried out to determine the influence on the natural frequency, and buckling and collapse pressures, of shell size, shell thickness, material properties, and support conditions.
Keywords: Finite element method - Toroidal shell - Vibration - Buckling - Collapse load
Dynamic response of a porous seabed–pipeline interaction under wave loading: Soil–pipeline contact effects and inertial effects
M. Luana, P. Qua, D.-S. Jenga,b, Y. Guoa, Q. Yanga
aState Key Laboratory of Coastal and O.shore Engineering, Institute of Geotechnical Engineering, School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 11604, China
bSchool of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia
Computers and Geotechnics 35 (2008) 173–186
Abstract: The existing models for the pore pressure and internal stresses within the pipeline under wave loading have mainly based on the assumption of no-slip boundary condition at the interface between pipeline and soil particles. In this paper, soil–pipeline contact effects and inertial forces are considered in the new model. A comprehensive comparison between the experimental data available and the present
model is performed and showing good agreements. Based on the numerical results, it is found that soil–pipeline contact effects significantly affect the internal stresses. The maximum difference of internal normal stress can reach 50 times of p0. On the other hand, inclusion of inertial terms will only affect the pore pressure acting on the pipeline. Numerical examples also conclude that the difference of internal normal stresses between the present model (with contact effects and inertial terms) and previous work (without contact effects and inertial terms) increases as the depth (s) of the trench layer decreases, but as the width of the trench layer (l) increases. Finally, we compare three different types of trench shapes, rectangle, trapezoid and triangle trench layers, and found that triangle trench layer will reduce the pore pressure, but increase the internal stresses.
Keywords: Contact effects - Inertial force - Pore pressure - nternal stress - Wave–soil–pipeline interaction
On the transformation toughening of a crack along an interface between a shape memory alloy and an isotropic medium
Yuval Freed, Leslie Banks-Sills, Jacob Aboudi
The Dreszer Fracture Mechanics Laboratory, Department of Solid Mechanics, Materials and Systems, The Fleischman Faculty of Engineering, Tel Aviv University, 69978 Ramat Aviv, Israel
Journal of the Mechanics and Physics of Solids 56 (2008) 3003– 3020
Abstract: In this study, a bilinear cohesive zone model is employed to describe the transformation toughening behavior of a slowly propagating crack along an interface between a shape memory alloy and a linear elastic or elasto-plastic isotropic material. Small scale transformation zones and plane strain conditions are assumed. The crack growth is numerically simulated within a finite element scheme and its transformation toughening is obtained by means of resistance curves. It is found that the choice of the cohesive strength t0 and the stress intensity factor phase angle f greatly influence the toughening behavior of the bimaterial. The presented methodology is generalized for the case of an interface crack between a fiber reinforced shape memory alloy composite and a linear elastic, isotropic material. The effect of the cohesive strength t0, as well as the fiber volume fraction are examined.
Keywords: Phase transformation - Fracture mechanisms - Delamination - Finite elements - Shape memory alloys
A cell culturing system that integrates the cell loading function on a single platform and evaluation of the pulsatile pumping effect on cells
J. Y. Kim1,4, H. Park1,4, K. H. Kwon1,4, J. Y. Park1,4, J. Y. Baek1,4, T. S. Lee2, H. R. Song3, Y. D. Park1,4, S. H. Lee1,4
1Department of Biomedical Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-701, South Korea
2Department of Biomedical Engineering, Chungbuk National University, Cheongju, Chungbuk 361-763, South Korea
3Department of Orthopedic Surgery, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-701, South Korea
4Korea Artificial Organ Center, Korea University, Anam-dong Seongbuk-gu, Seoul 136-701, South Korea
Biomed Microdevices (2008) 10:11–20
Abstract: In this paper, we present a novel microfluidic system with pulsatile cell storing, cell-delivering and cell culturing functions on a single PDMS platform. For this purpose, we have integrated two reservoirs, a pulsatile pumping system containing two soft check valves, which were fabricated by in situ photopolymerization, six switch valves, and three cell culture chambers all developed through a simple and rapid fabrication process. The sample volume delivered per stroke was 120 nl and the transported volume was linearly related to the pumping frequency. We have investigated the effect of the pulsatile pneumatic micropumping on the cells during transport. For this purpose, we pumped two types of cell suspensions, one containing human breast adenocarcinoma cells (MCF-7) and the other mesenchymal stem cells (hMSCs) derived from bone marrow. The effect of pulsatile pumping on both cell types was examined by short and long-term culture experiments. Our results showed that the characteristics of both cells were maintained; they were not damaged by the pumping system. Evaluations were carried out by morphological inspection, viability assay and immunophenotyping analysis. The delivered MCF-7 cells and hMSCs spread and proliferated onto the gelatin coated cell culture chamber. This total micro cell culture system can be applied to cellbased high throughput screening and for co-culture of different cells with different volume.
Keywords: Microchannel - Cell culture - Microfluidic - Micropump - PDMS - In situ photopolymerization
A finite element framework for computation of protein normal modes and mechanical response
Arnold Sommerfeld Zentrum für Theoretische Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Theresienstrasse 37, 80333 Munich, Germany
Proteins: Structure, Function, and Bioinformatics (2008) Volume 70 Issue 4, Pages 1595 - 1609
A computational framework based on the Finite Element Method is presented to calculate the normal modes and mechanical response of proteins and their supramolecular assemblies. Motivated by elastic network models, proteins are treated as continuum elastic solids with molecular volume defined by their solvent-excluded surface. The discretized Finite Element representation is obtained using a surface simplification algorithm that facilitates the generation of models of arbitrary prescribed spatial resolution. The procedure is applied to a mutant of T4 phage lysozyme, G-actin, syntenin, cytochrome-c, beta-tubulin, and the supramolecular assembly filamentous actin (F-actin). Equilibrium thermal fluctuations of alpha-carbon atoms and their inter-residue correlations compare favorably with all-atom-based results, the Rotational-Translational Block procedure, and experiment. Additionally, the free vibration and compressive buckling responses of F-actin are in quantitative agreement with experiment. The proposed methodology is applicable to any protein or protein assembly and facilitates the incorporation of specific atomic-level interactions, including aqueous-electrolyte-mediated electrostatic effects and solvent damping. The procedure is equally applicable to proteins with known atomic coordinates as it is to electron density maps of proteins, protein complexes, and supramolecular assemblies of unknown atomic structure.
Keywords: coarse-grain - modeling - simulation - normal mode analysis - actin
A fluid-immersed multi-body contact finite element formulation for median nerve stress in the carpal tunnel
Cheolwoong Ko and Thomas D. Brown
Department of Orthopaedics and Rehabilitation University of Iowa, Iowa City, IA 52242-1100, USA
Comput Methods Biomech Biomed Engin. 2007 October ; 10(5): 343–349.
Abstract: Carpal tunnel syndrome (CTS) is among the most important of the family of musculoskeletal disorders caused by chronic peripheral nerve compression. Despite the large body of research in many disciplinary areas aimed at reducing CTS incidence and/or severity, means for objective characterization of the biomechanical insult directly responsible for the disorder have received little attention. In this research, anatomical image-based human carpal tunnel finite element (FE) models were constructed to enable study of median nerve mechanical insult. The formulation included largedeformation multi-body contact between the nerve, the nine digital flexor tendons, and the carpal tunnel boundary. These contact engagements were addressed simultaneously with nerve and tendon fluid-structural interaction (FSI) with the synovial fluid within the carpal tunnel. The effects of pertinent physical parameters on median nerve stress were explored. The results suggest that median nerve stresses due to direct structural contact are typically far higher than those from fluid pressure.
Keywords: Carpal tunnel syndrome - Finite element method - Mechanical insult - Median nerve - Flexor tendon - Solid stress - Fluid pressure
Novel model to analyze the effect of a large compressive follower pre-load on range of motions in a lumbar spine
Susan M. Rennera,d, Raghu N. Natarajana,b, Avinash G. Patwardhanc,d, Robert M. Haveyc,d, Leonard I. Voronovd, Bev Y. Guod, Gunnar B.J. Anderssonb, Howard S. Anb
aBioengineering, University of Illinois at Chicago, Chicago, IL, USA
bDepartment of Orthopedic Surgery, Rush University Medical Center, Chicago, IL, USA
cDepartment of Orthopedic Surgery and Rehabilitation, Loyola University Medical Center, Maywood, IL, USA
dMusculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, IL, USA
Journal of Biomechanics 40 (2007) 1326–1332
A 3-D finite element model (FEM) of the lumbar spine (L1–S1) was used to determine the effect of a large compressive follower pre-load on range of motions (ROM) in all three planes. The follower load modeled in the FEM produced minimal vertebral rotations in all the three planes. The model was validated by comparing the disc compression at all levels in the lumbar spine with the corresponding results obtained by compressing 10 cadevaric lumbar spines (L1–S1) using the follower load technique described by Patwardhan et al. [1999. A follower load increases the load-carrying capacity of the lumbar spine in compression. Spine 24(10), 1003–1009]. Further validation of the model was performed by comparing the lateral bending and torsion response without pre-load and the .exion–extension response without pre-load and with an 800N follower pre-load with those obtained using cadaver lumbar spines. Following validation, the FEM was subjected to bending moments in all three planes with and without compressive follower pre-loads of up to 1200 N. Disc compression values and the flexion–extension range of motion under 800N follower pre-load predicted by the FEM compared well with in vitro results. The current model showed that compressive follower pre-load decreased total as well as segmental ROM in flexion–extension by up to 18%, lateral bending by up to 42%, and torsion by up to 26%.
Keywords: Follower load - Lumbar spine - Kinematics - Finite element
Fluid-structure analysis of microparticle transport in deformable pulmonary alveoli
H.L. Daileya, S.N. Ghadialia,b
aMechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA
bBioEngineering Program, Lehigh University, Bethlehem, PA 18015, USA
Aerosol Science 38 (2007) 269 – 288
Abstract: Micron-sized particles inhaled into the respiratory system can traverse the airway tree and deposit on the walls of the pulmonary alveoli. The fate of these particles can be measured by their propagation depth, wall deposition rate, and time to impaction. These three quantities depend on various physical parameters including particle size, alveolar geometry, tissue properties, and breathing patterns. In this study, we develop a 2-D fluid-structure computational model of alveolar dynamics to quantify how these parameters influence particle transport in the deep lung. The computational model simulates negative pressure breathing conditions in which applied tissue forces deform the lung parenchyma and produce oscillatory flow within the alveoli. Alveolar flow patterns are used to calculate the trajectories of micron-sized particles (i.e. 0.1–5 µm) by solving the Langevin equation, which contains a stochastic Brownian force term. As a result, these fluid-structure models can be used to investigate how tissue mechanical properties and breathing patterns influence deep-lung flow fields and particle dynamics. Results indicate that Brownian diffusion dominates the transport of small particles (dp < 0.5 µm), while gravitational sedimentation dominates the transport of large particles (dp> 1 µm). Mid-size particles (0.5 ≤ dp ≤ 1 µm)experience slower diffusion and slower sedimentation transport, so their time to impaction is maximized. Stiffer tissues produce higher particle impaction rates under microgravity conditions while tissue viscosity has negligible effects on particle dynamics.We also compare our computational results to previously published experimental studies and conclude that targeting inhaled particles to the deep lungs increases whole-lung deposition efficiencies because diffusion and sedimentation are efficient transport mechanisms in the small, distal structures.
Keywords: Brownian diffusion - Deep-lung deformation - Alveolar mechanics - Tissue mechanics - Biofluid mechanics - Microgravity - Drug delivery - Viscoelasticity - Fluid-structure interactions - ADINA
Martian jumping rover equipped with electroactive polymer actuators: A preliminary study
Federico Carpi1, Aldo Tralli2, Danilo De Rossi1, Paolo Gaudenzi2
1University of Pisa
2University of Rome “La Sapienza”
IEEE Transactions On Aerospace And Electronic Systems Vol. 43, No. 1 Jan 2007
Abstract: This paper presents results of a preliminary study of feasibility for the application of electroactive polymer (EAP) based actuators to a robotic locomotion system, intended by the European Space Agency (ESA) to operate on the surface of Mars. The system is conceived as an elastic spherical rover, exploiting wind propulsion for surface motion, while adopting an active mechanism for vertical jumping over obstacles. The use of polymeric electromechanical devices is envisaged in order to provide actuation to such a jumping mechanism. Among the available EAP technologies, new contractile linear actuators based on dielectric elastomers are proposed in this study as suitable devices and two potential solutions concerning their use are designed, modeled, and evaluated via numerical simulations. Thebest solution reveals interesting simulated performances, enabling jumping of obstacle heights corresponding to more than 7% of the diameter of the rover.
A numerical study of the flow-induced vibration characteristics of a voice-producing element for laryngectomized patients
S.L. Thomsona, J.W. Tackb, G.J. Verkerkeb,c
aDepartment of Mechanical Engineering, Brigham Young University, 435 CTB, Provo, UT, USA
bDepartment of BioMedical Engineering, University Medical Center Groningen, University of Groningen, The Netherlands
cDepartment of Biomechanical Engineering, University of Twente, The Netherlands
Journal of Biomechanics 40 (2007) 3598–3606
Abstract: A computational model for exploring the design of a voice-producing voice prosthesis, or voice-producing element (VPE), is presented. The VPE is intended for use by laryngectomized patients who cannot benefit from current speech rehabilitation techniques. Previous experiments have focused on the design of a double-membrane voice generator as a VPE. For optimization studies, a numerical model has been developed. The numerical model introduced incorporates the finite element (FE) method to solve for the flow-induced vibrations of the VPE system, including air flow coupled with a mass-loaded membrane. The FE model includes distinct but coupled fluid and solid domains. The flow solver is governed by the incompressible, laminar, unsteady Navier–Stokes equations. The solid solver allows for large deformation, large strain, and collision. It is first shown that the model satisfactorily represents previously published experimental results in terms of frequency and flow rate, enabling the model for use as a design tool. The model is then used to study the in.uence of geometric scaling, membrane thickness, membrane stiffness, and slightly convergent or divergent channel geometry on the model response. It is shown that physiological allowable changes in the latter three device parameters alone will not be sufficient to generate the desired reduction in fundamental frequency. However, their effects are quantified and it is shown that membrane stiffness and included angle should be considered in future designs.
Keywords: Voice-producing element - Voice prosthesis - Flow-induced vibrations - Finite element model - Total laryngectomy
Fluid-Structure Coupled Analyses of Composite Wind Turbine Blades
Tai-Hong Cheng1, Il-Kwon Oh2
1School of Mechanical Engineering, Chonnam National University, 300
Yongbong-dong, Buk-gu, Gwang-Ju, 500-757, Republic of Korea
2School of Mechanical Systems Engineering, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwang-Ju, 500-757, Republic of Korea
Advanced Materials Research Vols. 26-28 (2007) pp 41-44
Abstract: The composite rotor blades have been widely used as an important part of the wind power generation systems because the strength, stiffness, durability and vibration of composite materials are all excellent. In composite laminated blades, the static and dynamic aeroelasticity tailoring can be performed by controlling laminate angle or stacking sequence. In this paper, the fluid-structure coupled analyses of 10kW wind turbine blades has been performed by means of the full coupling between CFD and CSD based finite element methods. Fiber enforced composites fabricated with three types of stacking sequences were also studied. First the centrifugal force was considered for the nonlinear static analyses of the wind turbine so as to predict the deformation of tip point in the length direction and maximum stress in the root of a wind turbine. And then, the aeroelastic static deformation was taken into account with fluid-structure interaction analysis of the wind turbine. The Arbitrary Lagrangian Eulerian Coordinate was used to compute fluid structure interaction analysis of the wind turbine by using ADINA program. The displacement and stress increased apparently with the increment of aerodynamic force, but under the condition of maximum rotation speed 140RPM of the wind turbine, the displacement and stress were in the range of safety.
Keywords: Composite laminate shells - Quasi-isotropic - Fluid-Structure Interaction - ALE(ArbitraryLagrangian Eulerian) Coordinate
Crack growth resistance of shape memory alloys by means of a cohesive zone model
Yuval Freed, Leslie Banks-Sills
The Dreszer Fracture Mechanics Laboratory, Department of Solid Mechanics, Materials and Systems, The Fleischman Faculty of Engineering, Tel Aviv University, 69978 Ramat Aviv, Israel
Journal of the Mechanics and Physics of Solids 55 (2007) 2157–2180
Abstract: Crack growth resistance of shape memory alloys (SMAs) is dominated by the transformation zone in the vicinity of the crack tip. In this study, the transformation toughening behavior of a slowly propagating crack in an SMA under plane strain conditions and mode I deformation is numerically investigated. A small-scale transformation zone is assumed. A cohesive zone model is implemented to simulate crack growth within a finite element scheme. Resistance curves are obtained for a range of parameters that specify the cohesive traction–separation constitutive law. It is found that the choice of the cohesive strength t0 has a great in.uence on the toughening behavior of the material. Moreover, the reversibility of the transformation can signi.cantly reduce the toughening of the alloy. The shape of the initial transformation zone, as well as that of a growing crack is determined. The effect of the Young’s moduli ratio of the martensite and austenite phases is examined.
Keywords: Phase transformation - Fracture mechanics - Finite elements - Numerical algorithms - Shape memory alloys