ADINA Publications

Page 21

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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Dynamic Behaviour Of Compliant Towers In Deep Sea

G.F. Clauss, J.Y. Lee

Institute of Land and Sea Transportation, Division of Ocean Engineering, Technical University of Berlin, Salzufer 17-19, D-10587 Berlin, Germany

Proc. OMAE03 22nd Int. Conf. on Offshore Mechanics and Arctic Engineering, Mexico, 2003

Abstract: For oil and gas production in deep water (500m) compliant structures are designed. By dedicated reduction of stiffness and optimization of mass (including added mass contributions) the fundamental period is tuned to about 30s, which is well above the period range of significant wave energy. This paper presents the results of a comprehensive numerical analysis of the hydroelastic behaviour of compliant towers in deep water, investigating the dynamic response of a flexible structure in a given sea state. The numerical program system is based on ADINA with an integrated hydrodynamic module for wave/structure interaction. Nonlinear effects of viscous forces are considered using Morison’s vector equation. In addition nonlinear characteristics of soil/structure interaction are also included according to API regulations. At first, for verification of the program system, the numerical results of a monotower are compared to analytical solutions obtained by modal analysis of the structure in regular and irregular seas. Based on the validated program a compliant tower installed in 503 m water in the Gulf of Mexico (Baldpate tower) is modeled in 3D, and the characteristic dynamic behavior is evaluated. Finally, the tower is exposed to a real ”freak” wave (the 25.6m high New YearWave which has been registered at the North Sea Draupner platform on January 1, 1995), and the associated loads and motions are evaluated.

Instability analysis of some fluid–structure interaction problems

Xiaodong Wang

Department of Mechanical Engineering, Polytechnic University, Six MetroTech Center, Brooklyn, NY 11201, USA

Computers & Fluids, 32:121–138, 2003

Abstract: In this paper,we present instability analysis of two fluid–structure interaction (FSI) problems in the papermaking process. The first mathematical model is related to a pipe mixing unit which involves the submerged and inclined concentric pipes with different lengths. In the case of steady flow,both buckling and flutter instabilities are investigated. In the case of pulsatile flow, we use the numerical Floquet method to compute the eigenvalues of the monodromy matrix derived from the discretized linear system with periodic coefficients. In addition, for a special case, in which the concentric pipes have the same length, we also introduce a traditional Bolotin approach for comparison. The second mathematical model is derived from a vane/fluid interaction system within the papermachine headbox in which high-speed flows are separated by long flexible vanes. It is shown that for both laminar and turbulent flow conditions, the steady results derived from such analytical approaches match the corresponding computational solutions obtained using a general-purpose FSI computational package. Although, for certain cases, when geometries of fluid or solid domains are complex,it is very advantageous to use such a general-purpose program, we also point out, through the discussion of the selection of the critical time step in the numerical Floquet analysis and the dynamic stability analysis involving pulsatile flows, that there is still a need for analytical approaches as discussed in this paper.

 

Finite element models in the steel industry — Part II: analyses of tubular products performance

E.N. Dvorkin and R.G. Toscano

Center for Industrial Research, FUDETEC, Av. Córdoba 320, 1054 Buenos Aires, Argentina

Computers and Structures, 81(8-11):575-594, 2003

Abstract: In this paper we discuss the finite element models that we developed for simulating the service performance of the tubular steel products used in the oil industry. These tubular products include the oil country tubular goods (OCTG), that is to say the tubular products used in the oil wells, and the pipes used in pipeline applications.

Keywords: Computer simulation — Finite element method — Oil wells — Performance — Tubular steel structures

 

Effect of Stenosis Asymmetry on Blood Flow and Artery Compression: A Three-Dimensional Fluid-Structure Interaction Model

D. Tang1, C. Yang2,  S. Kobayashi3, J. Zheng4, and R.P. Vito5

1 Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA
2 Mathematics Department, Beijing Normal University, China
3 Department of Functional Machinery and Mechanics, Shinshu University, Nagano, Japan
4 Mallinkcrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
5 School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA

Annals of Biomedical Engineering, 31:1182–1193, 2003

Abstract: A nonlinear three-dimensional thick-wall model with fluid-structure interactions is introduced to simulate blood flow in carotid arteries with an asymmetric stenosis to quantify the effects of stenosis severity, eccentricity, and pressure conditions on blood flow and artery compression (compressive stress in the wall). Mechanical properties of the tube wall are measured using a thick-wall stenosis model made of polyvinyl alcohal hydrogel whose mechanical properties are close to that of carotid arteries. A hyperelastic Mooney–Rivlin model is used to implement the experimentally measured nonlinear elastic properties of the tube wall. A 36.5% pre-axial stretch is applied to make the simulation physiological. The Navier–Stokes equations in curvilinear form are used for the fluid  model. Our results indicate that severe stenosis causes critical flow conditions, high tensile stress, and considerable compressive stress in the stenosis plaque which may be related to artery compression and plaque cap rupture. Stenosis asymmetry leads to higher artery compression, higher shear stress and a larger flow separation region. Computational results are verified by available experimental data.

Keywords: Stroke — Heart attack — Plaque cap rupture — Collapsible — Finite difference — Fluid-structure interaction — Nonlinear elasticity — Iterative — Generalized finite difference

 

Numerical Analysis of the Three-Dimensional Blood Flow in the Korean Artificial Heart

E.B. Shim1, J.Y. Yeo1, H.J. Ko1, C.H. Youn2, Y.R. Lee3, C.Y. Park4, B.G. Min4, and K. Sun5

1 Department of Mechanical Engineering, Kumoh National University of Technology, Kyungbuk, Kumi;
2 School of Engineering, Information and Communication University, Taejeon;
3 Department, National Computerization Agency, Seoul,
4 Department of Biomedial Engineering, Seoul National University, Seoul; and
5 Department of Thoracic and Cardiovascular Surgery, Seoul, South Korea

Artificial Organs, 27(1):49–60, 2003

Abstract: Flow in the blood sac of the Korean artificial heart is numerically simulated by finite element method. Fluid-structure interaction algorithm is employed to compute the three-dimensional blood flow interacting with the sac material. For verification of the numerical method of fluid-structure interaction, two-dimensional flow in a collapsible channel with initial tension is simulated and the results are compared with numerical solutions from the literature. Incompressible viscous flow and linear elastic solid are assumed for the blood and the sac material in the device, respectively. The motion of the actuator is simplified by a time-varying pressure boundary condition imposed on the outer surface of the sac. Numerical solutions on the unsteady three-dimensional blood flow in the sac are provided for the cactus-type model in this study. During systole, the inlet is closed and the blood sac is squeezed by the action of the prescribed pressure on the surface. During diastole, the sac is filled with the blood coming from the inlet while the outlet is closed. A strong flow to the outlet and a stagnated flow near the inlet are observed during systole. Shear stress distribution is also delineated to assess the possibility of thrombus formation. We also simulate numerically the hemodynamics of “the reversed model” where the inlet and outlet are reversed for surgical convenience. It is observed that a recirculating flow was generated near the inner corner of the sac in the reversed model. To assess the material strength of the sac, the shear stress distribution in the solid material is also presented.

Keywords: Korean artificial heart — Three dimensional blood flow — Fluid-structure interaction method — Reversed model — Shear stress distribution

 

Instability analysis of some fluid-structure interaction problems

X. Wang

Department of Mechanical Engineering, Polytechnic University, Six MetroTech Center, Brooklyn, NY 11201, United States

Computers & Fluids 32:121–138, 2003

Abstract: In this paper, we present instability analysis of two fluid-structure interaction (FSI) problems in the papermaking process. The first mathematical model is related to a pipe mixing unit which involves the submerged and inclined concentric pipes with different lengths. In the case of steady flow, both buckling and flutter instabilities are investigated. In the case of pulsatile flow, we use the numerical Floquet method to compute the eigenvalues of the monodromy matrix derived from the discretized linear system with periodic coefficients. In addition, for a special case, in which the concentric pipes have the same length, we also introduce a traditional Bolotin approach for comparison. The second mathematical model is derived from a vane/fluid interaction system within the papermachine headbox in which high-speed flows are separated by long flexible vanes. It is shown that for both laminar and turbulent flow conditions, the steady results derived from such analytical approaches match the corresponding computational solutions obtained using a general-purpose FSI computational package. Although, for certain cases, when geometries of fluid or solid domains are complex, it is very advantageous to use such a general-purpose program, we also point out, through the discussion of the selection of the critical time step in the numerical Floquet analysis and the dynamic stability analysis involving pulsatile flows, that there is still a need for analytical approaches as discussed in this paper.

Keywords: Buckling — Linear systems — Mathematical models — Matrix algebra — Papermaking — Papermaking machinery — Pipe — Pulsatile flow — Stability — Steady flow —  Turbulent flow

 

Nonlinear time history analysis for the seismic retrofit of the Richmond-San Rafael Bridge

R.A. Dameron1, D.R. Parker2, T. Dahlgren3

1 David Evans & Associates, San Diego, CA, USA
2 ANATECH Corp., San Diego, CA, USA
3 Ben C. Gerwick, Inc., San Francisco, CA, USA

Computational Fluid and Solid Mechanics 2003, 2003

Abstract: The Richmond-San Rafael Bridge carries four lanes of Interstate 580 over the northern portion of San Francisco Bay between the cities of San Rafael and Richmond. It was included in the California State Toll Bridge Retrofit Program in the 1990s . Caltrans commissioned the retrofit design to a joint venture of Ben C. Gerwick, Inc., DMJM+Harris, and Jacobs-Sverdrup, with support from subconsultants, including structural analysis performed by ANATECH Corp. and ICF Kaiser Engineers. ANATECH performed global nonlinear time history analysis using the ADINA program as a project deliverable. This paper describes the modeling assumptions and approach, with emphasis on the decision making required to balance model refinement against practical limits on run times and usability of results. The paper concludes with a summary of lessons learned from this and other toll bridge global analyses conducted during the California bridge seismic retrofit program.

Keywords: Richmond-San Rafael Bridge — Nonlinear analysis — Soil-structure interaction — Isolation bearings — Nonlinear dampers

 

Elastohydrodynamic separation of pleural surfaces during breathing

A. Gouldstone1, R.E. Brown2, J.P. Butler1, S.H. Loring2

1 Physiology Program, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA
2 Department of Anesthesia, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA

Respiratory Physiology & Neurobiology, 137:97-106, 2003

Abstract: To examine effects of lung motion on the separation of pleural surfaces during breathing, we modeled the pleural space in two dimensions as a thin layer of fluid separating a stationary elastic solid and a sliding flat solid surface. The undeformed elastic solid contained a series of bumps, to represent tissue surface features, introducing unevenness in fluid layer thickness. We computed the extent of deformation of the solid as a function of sliding velocity, solid elastic modulus, and bump geometry (wavelength and amplitude). For physiological values of the parameters, significant deformation occurs (i.e. bumps are ‘flattened’) promoting less variation in fluid thickness and decreased fluid shear stress. In addition, deformation is persistent; bumps of sufficient wavelength, once deformed, require a recovery time longer than a typical breath-to-breath interval to return near their undeformed configuration. These results suggest that
in the pleural space during normal breathing, separation of pleural surfaces is promoted by the reciprocating sliding of lung and chest wall.

Keywords: Computational fluid dynamics - Finite element analysis - Mechanics of breathing; Pleural surface separation - Model - Pleural separation - Pleura - Surface - Separation during breathing

 

Elasto-plastic modeling of wood bolted connections

Kharouf, N. (Department of Civil Engineering, McGill University); McClure, G.; Smith, I. Source: Computers and Structures, v 81, n 8-11, May, 2003, p 747-754

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: A plasticity based constitutive compressive material model is proposed to model wood as elasto-plastic orthotropic according to the Hill yield criterion in regions of bi-axial compression. Linear elastic orthotropic material response is applied otherwise with maximum stresses taken as failure criteria. The model is implemented in the finite element code to carry out the analysis of bolted connections using ADINA software. Reasonable agreement is found between numerical simulations and experimental measurements of local and global deformation of one-bolt connection. The predicted failure modes are consistent with experimental observations. (20 refs.)

Keywords:  Wood  -  Elastoplasticity  -  Compressive stress  -  Connectors (structural)  -  Finite element method  -  Computer software  -  Computer simulation

Secondary  Keywords:  Wood bolted connections


Modeling the structural dynamic response of overhead transmission lines

McClure, G. (Department of Civil Engineering, McGill University); Lapointe, M. Source: Computers and Structures, v 81, n 8-11, May, 2003, p 825-834

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: Static analysis forms the basis of calculations in structural design of overhead power lines. The environmental loads considered in design can be assumed static (icing) or quasi-static (idealized steady wind). However, dynamic analysis is necessary to predict line transient response to shock loads such as those induced by the sudden failure of components or sudden ice-shedding effects on the conductors. This paper summarizes a macroscopic modeling approach to line dynamic analysis where emphasis is put on capturing the salient features of the propagation of such shock loads in a line section. The approach is illustrated with a case study of a line section having suffered two tower failures due to conductor breakages during an ice storm. The cable dynamics model proposed has been applied successfully to several examples, using the commercial software ADINA. © 2003 Elsevier Science Ltd. All rights reserved. (20 refs.)

Keywords:  Overhead lines  -  Dynamic response  -  Structural design  -  Transients  -  Electric cables  -  Electric conductors  -  Finite element method  -  Computer software

Secondary  Keywords:  Cable dynamics


Near-surface stress states in flexible pavements using measured radial tire contact stresses and ADINA

Novak, Marc (Department of Civil Engineering, University of Florida); Birgisson, Bjorn; Roque, Reynaldo Source: Computers and Structures, v 81, n 8-11, May, 2003, p 859-870

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: The finite element code ADINA was used to identify the three-dimensional stress states in a typical flexible pavement configuration, resulting from measured radial tire contact stresses. The predictions show that measured radial tire contact stresses result in stress states being both larger in magnitude and more focused near the surface than those obtained from traditional uniform vertical loading conditions. In terms of effects of possible pavement damage mechanisms, predicted high near-surface shear stresses may be a part of an explanation for near-surface rutting failure modes, as supported by near-surface slip planes seen in the field. © 2003 Elsevier Science Ltd. All rights reserved. (22 refs.)

Keywords:  Pavements  -  Flexible structures  -  Shear stress  -  Tires  -  Finite element method

Secondary  Keywords:  Contact stresses

 


Finite element analysis modeling of ingot refusal conditions during the rolling process

Ognjanovic, Rade (Alcan International Ltd., Banbury Laboratories); Waterson, Keith Source: Computers and Structures, v 81, n 8-11, May, 2003, p 871-877

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: This paper deals with modeling of refusal conditions of aluminium ingots as they enter the work roll gap during the rolling process. The rolling process rolls ingots into thinner ingots. Under some rolling conditions the ingot will bounce back from the work rolls or "refuse". Two dimensional finite element (FE) modeling was done to study this phenomenon and an analytical form of the refusal conditions was derived. Two FE packages (ADINA and ABAQUS/Standard) were used and significant differences in simulation results were noted between the two packages. The FE model was applied to an industrial problem. © 2003 Elsevier Science Ltd. All rights reserved. (9 refs.)

Keywords:  Ingots  -  Rolling  -  Aluminum  -  Finite element method  -  Computer simulation

Secondary  Keywords:  Ingot refusal

 


Process of hip joint prosthesis design including bone remodeling phenomenon

Pawlikowski, M. (Warsaw University of Technology); Skalski, K.; Haraburda, M. Source: Computers and Structures, v 81, n 8-11, May, 2003, p 887-893

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: The design of hip joint prostheses is very complex process which requires close co-operation between engineers and surgeons. To design a prosthesis of higher durability one has to take natural processes occurring in bone into consideration. In the paper a process of hip joint prosthesis design is described. The design process was performed for a particular patient who suffered from severe trauma of a hip joint. A set of three prostheses was created and then some numerical calculations were carried out with the use of ADINA system. The visco-elastic properties of bone and the bone remodeling phenomenon were taken into consideration, which is a novel approach in prosthesis design. The results of the numerical analyses allowed us to decide which one of the three designed prostheses is the most capable for the patient. This way the shape optimisation process is completed. As a result of it the load acting on the designed prosthesis will be anatomically adopted by the femur. © 2003 Elsevier Science Ltd. All rights reserved. (13 refs.)

Keywords:  Hip prostheses  -  Bone  -  Computerized tomography  -  Image analysis  -  Viscoelasticity  -  Finite element method  -  Optimization

Secondary  Keywords:  Bone density rate

 


Fluid-structure interaction analysis with a subsonic potential-based fluid formulation

Sussman, Theodore (ADINA R and D, Inc.); Sundqvist, Jan Source: Computers and Structures, v 81, n 8-11, May, 2003, p 949-962

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: We consider fluid-structure interaction problems in which the fluid flows are slightly compressible, inviscid and irrotational with no heat transfer, and in which the boundary motions of the fluid domains are small. These problems are efficiently solved using the subsonic potential-based fluid formulation presented in this paper. The formulation is efficient because the fluid modeling includes only one nodal point unknown, the velocity potential. A practical example from the nuclear industry, the HDR blowdown experiment, shows the efficiency and accuracy of the formulation. © 2003 Elsevier Science Ltd. All rights reserved. (21 refs.)

Keywords:  Computational fluid dynamics  -  Subsonic flow  -  Potential flow  -  Compressible flow  -  Structural analysis  -  Finite element method

Secondary  Keywords:  Irrotational flow


Recent development of fluid-structure interaction capabilities in the ADINA system

Zhang, Hou (ADINA R and D Inc.); Zhang, Xiaoli; Ji, Shanhong; Guo, Yanhu; Ledezma, Gustavo; Elabbasi, Nagi; DeCougny, Hugues Source: Computers and Structures, v 81, n 8-11, May, 2003, p 1071-1085

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: The ADINA system has been developed in recent years into a complete system for the analysis of solid, fluid and coupled problems. Fluid flows can be modeled as Navier-Stokes incompressible, slightly compressible and fully compressible flows. They can also be modeled as porous medium flows. Structures can be modeled as 2D/3D solids, beams or shells. The response of the structure can be linear or nonlinear, and can also include contact effects. The fluid and structure can be coupled through their interface (FSI), porous media (PFSI) or thermal materials (TFSI). Both iterative and direct solution procedures can be used for solving the fully coupled system. These capabilities, together with the extensive boundary conditions and material models, and the user-friendly graphical system for pre- and post-processing (AUI), make the ADINA system a powerful tool for engineers and researchers. © 2003 Elsevier Science Ltd. All rights reserved. (17 refs.)

Keywords:  Fluid structure interaction  -  Computational fluid dynamics  -  Compressible flow  -  Incompressible flow  -  Porous materials  -  Navier Stokes equations  -  Finite element method  -  Boundary conditions

Secondary  Keywords:  Thermal materials

 


Structural design of modern steam turbine blades using ADINA

Richter, Christoph-Hermann (Siemens AG, Power Generation, Department S322) Source: Computers and Structures, v 81, n 8-11, May, 2003, p 919-927

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: The present paper provides an overview of the structural design of modern steam turbine blades at Siemens power generation using the finite element code ADINA [trademark] . The different types of blades are described in detail regarding their geometry and loading. The modular building block approach of modelling is shown to be of essential importance. For the different analyses a fatigue post-processor has been implemented as well as an optimization tool. Both of these in-house codes will be briefly presented. © 2003 Elsevier Science Ltd. All rights reserved. (11 refs.)

Keywords:  Turbomachine blades  -  Steam turbines  -  Structural design  -  Finite element method  -  Optimization

Secondary  Keywords:  Turbine blades

 


Application of ADINA and hole drilling method to residual stress determination in weldments

Roy, George (Materials Technology Laboratory); Braid, Mac; Shen, Guowu Source: Computers and Structures, v 81, n 8-11, May, 2003, p 929-935

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: Residual stress distributions with depth at weld toes in controlled shot-peened, high strength steel weldments were determined through the measurement of relaxed surface strains by the incremental hole drilling method. The stress states were determined from the relaxed surface strains by a novel elasto-plastic interpretation of the strain readings, using the finite element software, ADINA. Residual stress distributions determined from the theory of elasticity, using experimental strain gauge readings from the hole drilling method, gave values much greater than the 0.2% offset yield stress of 613 MPa. The stress states were corrected through elasto-plastic finite element modeling using ADINA. After the corrections, the maximum residual stress was less than 613 MPa. The corrected stress distributions were applied to determine the effect of controlled shot peening on residual stress distributions with depth. The distributions within 0.8 mm below the material surface was used as an indicator of shot-peening depth and the effect of control parameters. Crown Copyright © 2003 Published by Elsevier Science Ltd. All rights reserved. (7 refs.)

Keywords:  Residual stresses  -  Computer software  -  Drilling  -  Welds  -  Elastoplasticity  -  Strain measurement  -  Structural analysis

Secondary Keywords:  Hole drilling methods  -  Strain relaxation

 


Formulation and study of thermal-mechanical coupling for saturated porous media

Wang, X. (College of Engineering and Science, Louisiana Tech University); Dong, J. Source: Computers and Structures, v 81, n 8-11, May, 2003, p 1019-1029

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: A formulation for the thermo-poro-elasto-plastic coupling analysis is presented, in which the energy balance equation is re-derived based on the concept of free enthalpy. The corresponding finite element procedures are developed and implemented into the commercial software ADINA. A complete solution strategy is described. The poro-mechanical and thermal coupling is conducted based on the simultaneous solution scheme for the isothermal poro-elasto-plastic interaction and the conventional thermal analysis. The complete solution procedures can be employed to solve both transient static and dynamic problems. The one-dimension column consolidation scenario is effectively re-examined with the proposed solution procedures, with heat and pore pressure dissipated on the top of the column. Accurate and reliable results with temperature and pore pressure distributions at different time steps are provided. © 2003 Elsevier Science Ltd. All rights reserved. (25 refs.)

Keywords:  Thermomechanical treatment  -  Porous materials  -  Elastoplasticity  -  Strain control  -  Pore pressure  -  Heat losses  -  Enthalpy  -  Computer software  -  Finite element method

Secondary  Keywords:  Thermal coupling

 


Dynamic buckling of cylindrical stringer stiffened shells

Yaffe, R. (Faculty of Aerospace Engineering, Technion, Israel Institute of Technology); Abramovich, H. Source: Computers and Structures, v 81, n 8-11, May, 2003, p 1031-1039

ISSN: 0045-7949 CODEN: CMSTCJ

Publisher: Elsevier Science Ltd

Abstract: The dynamic buckling of cylindrical stringer stiffened shells was investigated both numerically and experimentally. A new criterion to define the numerical "dynamic" buckling load was developed yielding consistent results. The ADINA finite element code was applied to simulate the static and dynamic buckling loads of the shells. It was shown numerically that when the period of the applied loading (half-wave sine) equals half the lowest natural period of the shell, there is a slight drop in the dynamic load amplification factor (DLF). The DLF is defined, as the ratio of the dynamic buckling to the static buckling of the shell. This factor drops below unity, when the ratio of the given sound speed in solids, c, to the velocity developed axially due to the applied dynamic loading, approaches unity. It means that, for this particular loading period, the dynamic buckling load would be lower than the static one. It was shown numerically that the shape of the loading period, half-wave sine, a shape encountered during the tests, as well as the initial geometric imperfections have a great influence on the dynamic buckling of the shells. The relatively simple test set-up design to cause a shell to buckle dynamically did not fulfill our expectations. Although, the process leading to eventually the dynamic buckling of the shell worked properly, still no test results were obtained to form a sound experimental database for this phenomenon. Based on the numerical predictions, correct guidelines were formulated for better test procedures to be applied in future tests, which will be reported in due time. © 2003 Elsevier Science Ltd. All rights reserved. (34 refs.)

Keywords:  Buckling  -  Shells (structures)  -  Dynamic response  -  Dynamic loads  -  Impact testing  -  Computer software  -  Finite element method

Secondary Keywords:  Dynamic buckling  -  Dynamic load amplification factor

 

Finite Element Analysis of CoSi2 Nanocrystals on Si(001)

I. Goldfarb1, L. Banks-Sills1, R. Eliasi1  and G.A.D. Briggs2

1Department of Solid Mechanics, Materials and Systems, The Fleischman Faculty of Engineering, Tel Aviv University, Ramat Aviv 69978, Israel
2Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK

Interface Science 10, 75–81, 2002

Abstract: In this work we present a finite element analysis of pyramidal and hut-shaped CoSi2 nanocrystals reactively deposited onto Si(001) substrates. These dots have been observed by us, as well as by other groups. Our analyses have yielded four major conclusions: (1) Elastic relaxation of CoSi2/Si mismatch strain by threedimensional islands drives their nucleation, rendering flat, two-dimensional, layer energetically unfavourable. (2) The effect of the nanocrystal surface and interface energies for the observed vertical aspect ratios is negligible at small nanocrystal volumes. (3) Pyramids and huts with identical vertical aspect ratios are energetically degenerate. (4) Nanocrystal growth is only energetically favourable if accompanied by an increase in vertical aspect ratio. Most of these conclusions are consistent with those found in compressively strained layers, such as Si1-xGex layers on Si.

Keywords: epitaxial cobalt silicide nanocrystals - scanning tunneling microscopy - finite element analysis - elastic and surface and interface energies - strain relaxation

 

Modelling and computations of contact joints using ADINA FEM system

Konowalski, K. (Departament of Mechanics, Technical University of Szczecin); Sobczak, L.; Grudzinski, K. Source: High Performance Structures and Materials, v 4, High Performance Structures and Composites, 2002, p 377-386

ISSN: 1469-0071

Conference: First International Conference on High Performance Structures and Composites, HIGH PERFORMANCE STRUCTURES AND COMPOSITES 2002, Mar 11-13 2002, Seville, Spain Sponsor: Wessex Institute of Technology, Southampton, UK

Publisher: WIT Press

Abstract: Paper presents results and experimental stand of contact strains at dynamic load. Grinded samples of nominal contact area 56,5 cm2 were subjected to investigations. For a given harmonic loads time functions of normal contact strains and their velocities were determined. The examined joint was appropriately modeled using FEM system ADINA. Applying an existing in the system model of the contact, characteristics (the same as in the experimental investigations) were determined. Comparing the experimental and computational results large discrepancies were observed. Therefore a thin intermediate layer was introduced to the computational model of the characteristic corresponding to that determined on the basis of experimental investigations. Such modified computational model delivered characteristics that are in accordance with the experimental results. (5 refs.)

Keywords:  Joints (structural components)  -  Computer programming  -  Damping  -  Data acquisition  -  Dynamic loads  -  Finite element method  -  Knowledge acquisition  -  Mathematical models  -  Parameter estimation  -  Problem solving  -  Velocity measurement

Secondary  Keywords:  Harmonic loads  -  Contact joints  -  Load distributions  -  Intermediate layers

 


Symulacja numeryczna wezla tarcia testera T-05 (Numerical simulation of a friction kinematical pair in the T-05 tester)

Lacki, Piotr (Politechnika Czestochowska) Source: Prace Naukowe Instytutu Konstrukcji i Eksploatacji Maszyn Politechniki Wroclawskiej/Scientific Papers of the Institute of Machine Design and Operation of the Technical University of Wroclaw, v 87, n 27, 2002, p 184-189 Language: Polish

ISSN: 0324-962X CODEN: PIKWD2

Conference: XXV Silver Jubilee School of Tribology; Tribology on the Threshold of the Third Millenium, Sep 23-26 2002, Ladek Zdroj, Poland

Publisher: Wydawnictwo Politechniki Wroclawskiej

Abstract: Nowadays numerical simulations are becoming a new source of information about the tested objects. Numerical modelling of the friction kinematical pairs is a difficult and complicated problem but giving varied information. In the paper a mechanical model of the T-05 tester has been presented. The friction cinematic pair was modelled with the Finite Element Method. Elastic model both of the specimen and counter-specimen material and a surface contact were taken into consideration. A development of the numerical model is possible. Calculations were carried out with the Adina System v.7.5. Numerous advantages taken of numerical simulations and a possibility for an application of numerical simulations to technique were pointed. (5 refs.)


Finite element simulation of the static characteristics of a vehicle rubber mount

Wang, L.-R. (Department of Automotive Engineering, Tsinghua University); Lu, Z.-H.; Hagiwara, I. Source: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, v 216, n 12, 2002, p 965-973

ISSN: 0954-4070 CODEN: PMDEEA

Publisher: Professional Engineering Publishing

Abstract: The static and dynamic characteristics of the rubber mounts for vibration isolation in automotive powertrains and other dynamic systems should be predicted during their design and development stage. In this paper, the static characteristic simulation of a rubber mount is performed using the finite element method. The modelling and simulation methods for a large deformation rubber spring represented by axisymmetric, quarter-symmetric and three-dimensional finite element models are investigated by using finite element analysis software PATRAN for meshing and ABAQUS and ADINA for computations. The predicted vertical static elastic characteristics of the rubber spring agree well with the experimental results. The static strain-stress analysis of the rubber part shows that the yon Mises stress can be adopted as a stress measure for the rubber material. Moreover, the modelling methods for the large deformation rubber mount are investigated with numerical tests of elastic characteristics. The hybrid elements with full integration and lower-order interpolation show less distortion and are suitable for large deformation simulation computations. The research results will help engineers and researchers to perform engineering design and analysis of rubber mounts and other vibration reduction rubber components using the finite element simulation method. (18 refs.)

Keywords:  Automotive engineering  -  Mountings  -  Rubber products  -  Vibrations (mechanical)  -  Deformation  -  Automobile springs  -  Stress analysis  -  Finite element method  -  Interpolation  -  Computer simulation

Secondary  Keywords:  Vehicle rubber mounts

 



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