ADINA Publications

Page 27

The Theory used in ADINA is richly documented in the following books by K.J. Bathe and co-authors


Finite Element Procedures
 

Finite Element Procedures in Engineering Analysis

Numerical Methods in Finite Element Analysis
 


The Mechanics of Solids and Structures — Hierarchical ...


The Finite Element Analysis of Shells — Fundamentals


Inelastic Analysis of Solids and Structures

 
 
To Enrich Life
(Sample pages here)
 

 

Following are more than 700 publications — that we know of — with reference to the use of ADINA. The pages give the Abstracts of some papers published since 1986 referring to ADINA. The most recent papers are listed first. All these papers may be searched using the box:

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Earthquake response properties of the support structure of large cross section tunnel

Jin, Xiao-Guang (College of Civil Engineering, Chongqing University); Zhang, Yong-Xing Source: Chongqing Jianzhu Daxue Xuebao/Journal of Chongqing Jianzhu University, v 30, n 1, February, 2008, p 44-48 Language: Chinese

ISSN: 1006-7329 CODEN: CJGXEK

Publisher: China National Publication Industry Trading Corporation

Abstract: The response properties of displacement and stress of tunnel support structure are discussed in detail under the action of horizontal earthquake acceleration (Ya), longitudinal earthquake acceleration (Za) and horizontal-longitudinal earthquake acceleration (YZa). This discussion is based on an analysis of the surrounding rock -support structure-earthquake interaction, adoption of an ADINA nonlinear finite element and construction mechanics, and transient dynamic time domain analysis of a large cross section tunnel. Results of analysis show that: (1) Horizontal earthquake acceleration has important influence on horizontal displacement, maximum principal stress, acceleration and velocity. (2) Longitudinal earthquake acceleration has important influence on longitudinal displacement, effective stress, maximum and minimum principal stress, maximum shear stress, acceleration and velocity. (3) When Ya=0.191 g and 0.440 g or Za=0.141 g and their combined action, the initial support of tunnel would be damaged and the local lining would have partial damage. (4) When Ya-0.440 g or Za=0.326 g and their combined action, the lining of tunnel would be damaged. (5) When Ya=0.880 g or 1 Za=0.652 g, the support structure of tunnel would have severe damage. (8 refs.)


Study on inner force and dislocation of segments caused by shield machine attitude

Mo, H.H. (Department of Civil Engineering, South China University of Technology); Chen, J.S. Source: Tunnelling and Underground Space Technology, v 23, n 3, May, 2008, p 281-291

ISSN: 0886-7798

Publisher: Elsevier Ltd

Abstract: Attitude deflection of shield machine is inevitable in process of driving forward, therefore, the tail brush, circular shape retainer and even shell of shield machine will extrude the exterior surfaces of segments. The squeezing action acting on segments causes dislocation, stress concentration and even crack in segments. Finite element code, ADINA, was used to analyze numerical tunnel model of 9 segment rings. The loads acting on different segment rings included squeezing action of tail brush under four attitude deflection, jacking forces, grouting pressure and earth pressure. The aspects of analysis included displacement feature and stress distribution. The analysis results indicate attitude deflection of shield machine causes biggish dislocation between segments, and the key segment is the most affected and weakest part in same ring which causes irregular displacement and dislocation in whole tunnel structure. In general, under squeezing action induced by shield machine, circumferential seam is much more affected than longitudinal seam. The squeezing action causes the segment dislocation exceed the limiting dislocation value which means curved bolt has extruded bolt hole and crack or breakage frequently concentrates in key segment and adjacent segment. Deflection of shield machine attitude is inevitable, but two deflection attitudes, including shield machine attitude deviates right direction and the head of shield machine goes down, should be avoided. © 2007 Elsevier Ltd. All rights reserved. (11 refs.)

Keywords:  Tunneling machines  -  Cracks  -  Deflection (structures)  -  Finite element method  -  Mathematical models  -  Pressure effects  -  Stress concentration  -  Structural loads  -  Tunnels

Secondary Keywords:  Shield machine attitude  -  Shield tunnel  -  Attitude deflection  -  Inner force


A finite element formulation based on non-associated plasticity for sheet metal forming

Cvitanic, Vedrana (Department of Mechanical Engineering and Naval Architecture, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture); Vlak, Frane; Lozina, Zeljan Source: International Journal of Plasticity, v 24, n 4, April, 2008, p 646-687

ISSN: 0749-6419 CODEN: IJPLER

Publisher: Elsevier Ltd

Abstract: In the present paper, a finite element formulation based on non-associated plasticity is developed. In the constitutive formulation, isotropic hardening is assumed and an evolution equation for the hardening parameter consistent with the principle of plastic work equivalence is introduced. The yield function and plastic potential function are considered as two different functions with functional form as the yield function of Hill [Hill, R., 1948. Theory of yielding and plastic flow of anisotropic metals. Proc. Roy. Soc. A 193, 281-297] or Karafillis-Boyce associated model [Karafillis, A.P. Boyce, M., 1993. A general anisotropic yield criterion using bounds and a transformation weighting tensor. J. Mech. Phys. Solids 41, 1859-1886]. Algorithmic formulations of constitutive models that utilize associated or non-associated flow rule coupled with Hill or Karafillis-Boyce stress functions are derived by application of implicit return mapping procedure. Capabilities in predicting planar anisotropy of the Hill and Karafillis-Boyce stress functions are investigated considering material data of Al2008-T4 and Al2090-T3 sheet samples. The accuracy of the derived stress integration procedures is investigated by calculating iso-error maps. The updated Lagrangian formulation of CBR shell element [Yoon, J.W., Yang, D.Y., Chung, K., 1999. Elasto-plastic finite element method based on incremental deformation theory and continuum based shell elements for planar anisotropic sheet materials. Comp. Meth. Appl. Mech. Eng. 174, 23-56] coupled with the developed constitutive formulations is implemented into the finite element program ADINA 8.1 (2003) via user defined subroutine CUSERG. The results of the cylindrical cup drawing for Al2008-T4 and Al2090-T3 sheet samples are evaluated by comparison with experimental data and predictions of Barlat [Barlat, F. et al., 1997b. Yield function development for aluminum alloy sheets. J. Mech. Phys. Solids 45, 1727-1763] associated model. © 2007 Elsevier Ltd. All rights reserved. (54 refs.)

Keywords:  Sheet metal  -  Algorithms  -  Aluminum alloys  -  Finite element method  -  Plasticity

Secondary  Keywords:  Anisotropic materials  -  Constitutive behavior

 


An Evaluation and Comparison of Models for Maximum Deflection of Stiffened Plates Using Finite Element Analysis

Banai, Lior (School of Mechanical Engineering, Tel Aviv University); Pedatzur, Omri. Source: Marine Technology, Vol. 44, No. 4, October 2007, pp. 212–225

ISSN: 0025-3316 (print); 1542-0566 (online)

Publisher: Society of Naval Architects and Marine Engineers

Abstract: Stiffened plates form the backbone of most of a ship’s structure. Today, finite element (FE) models are used to analyze the behavior of such structural elements for different types of loads. In the past, when usage of computers and FE models were not used very much, analytical analysis methods were required. Two well-known methods have been developed for analyses of stiffened plates under lateral loading (uniform pressure), based on two different models, namely, the orthotropic plate model and the grillage model. Both models can give estimations for the maximum plate deflection under uniform lateral pressure. The objective of this paper is to present the two methods, evaluate and compare the methods using the finite element method, and finally implement the methods as a computer program for quick estimations of the maximum deflection of stiffened plates. The degree of accuracy of the two methods when compared to FE is discussed in some detail.

Keywords: Stiffened plate - maximum deflection - lateral pressure - H. A. Schade - orthotropic model - grillage model

Secondary Keywords: finite element model - computer program - estimation - stiffener - ADINA

 

Study on material composition functions of gradient aluminum matrix composite piston reinforced by ceramic fibers

Wang, Su (Department of Automotive Engineering, Beijing University of Aeronautics and Astronautics); Ni, Chun-Yang; Zhu, Yu-Ming; Zhu, Xin-Xiong Source: Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica, v 28, n 1, January, 2007, p 234-239 Language: Chinese

ISSN: 1000-6893 CODEN: HAXUDJ

Publisher: AAAS Press of Chinese Society of Aeronautics and Astronautics

Abstract: Functionally gradient material components have better physical and chemical properties than homogeneous material components. Because of material distributing complexity and insufficient study on functionally gradient material, there are lots of difficulties in analysis of functionally gradient material components. Theory of thermal properties of composites and finite element analysis software ADINA are used to analyze the temperature field and stress field of gradient aluminum matrix composite piston reinforced by ceramic fibers which have different material composition functions. The result indicates that using gradient aluminum matrix composite layer reinforced by ceramic fibers can remarkably change the temperature distribution over the piston and relax the stresses at the interface between the gradient aluminum matrix composite layer reinforced by ceramic fibers and the noumenon of piston which is caused by mismatch among different thermal expansion coefficients. Based on the computing results, the curves of thermal peak value vs gradient function coefficient, entire stress peak value vs gradient function coefficient, and stress peak value between layers vs gradient function coefficient can be fitted and proved by computing other pistons. (8 refs.)

Keywords:  Pistons  -  Ceramic fibers  -  Chemical properties  -  Computer simulation  -  Finite element method  -  Functionally graded materials  -  Stress concentration  -  Temperature distribution  -  Thermal expansion  -  Thermodynamic properties

Secondary Keywords:  Functionally gradient material components  -  Temperature field  -  Stress field


Analysis of traffic flow based on the finite element method

Cui, Jian-Ming (College of Traffic and Transportation, Southwest Jiaotong University, Box 356); Ye, Huai-Zhen Source: International Conference on Transportation Engineering 2007, ICTE 2007, International Conference on Transportation Engineering 2007, ICTE 2007, 2007, p 94-99

Conference: International Conference on Transportation Engineering 2007, ICTE 2007, Jul 22-24 2007, Chengdu, China

Publisher: American Society of Civil Engineers

Abstract: Analysis of normal traffic flow usually uses the static or dynamic model based on fluid mechanics. However, in the analysis process, the problem of massive modeling and data handling exists, and the accuracy is desirable. Finite element method has been widely applied in various domains. Based on existing theory of traffic flow, ITS and the development of finite element, the paper presents a simulation method based on finite element for solving problems in traffic flow. Using existing finite element analysis software, the traffic flow is simulated and analyzed with fluid mechanics and dynamics. The problem with massive data processing through manual modeling and Numerical Analysis is solved. Finally, a typical case of special road is analyzed with ADINA finite element analysis software. Copyright ASCE 2007. (8 refs.)

Keywords:  Traffic control  -  Computer simulation  -  Computer software  -  Data handling  -  Dynamic models  -  Finite element method  -  Problem solving  -  Static analysis

Secondary  Keywords:  Traffic flow  -  Massive modelings  -  ADINA

 


An adhesion process for space solar cells

Zhao, H. (The Robotics Institute, School of Mechanical Engineering, Shanghai Jiao Tong University); Fu, Z.; Li, P.B.; Zhao, Y.Z. Source: Journal of Adhesion, v 83, n 12, December, 2007, p 1003-1029

ISSN: 0021-8464 CODEN: JADNAJ

Publisher: Taylor and Francis Inc.

Abstract: A type of silicone adhesive was used for bonding anti-irradiation cover glasses to space solar cells. A new adhesion process for solar cells was designed, and implemented by means of an automated coating and bonding system based on an industrial robot. On the basis of non-Newtonian fluid theory, flow models of three sub-processes were created, and the commercial finite element analysis code Adina was employed to simulate the whole process. The purpose of the investigation was to acknowledge the mechanism of the adhesion process and identify correlative factors that influence the adhesion quality, to provide a basis for optimization of the adhesion process. A simulation platform was created, to make it possible to evaluate or predict the adhesion quality of space solar cells when the dimensions of the solar cells and the adhesive were changed. (59 refs.)

Keywords:  Solar cells  -  Adhesion  -  Bonding  -  Coatings  -  Computer simulation  -  Dynamic mechanical analysis  -  Finite element method  -  Industrial robots  -  Optimization  -  Silicones

Secondary  Keywords:  Anti-irradiation cover  -  Correlative factors  -  Adhesion process  -  Adhesion quality

 


Studying on two yield-surface rheological model of frozen soil by unloading state

Li, Dong-Wei (Department of Civil Engineering, Anhui University of Science and Technology); Wang, Ren-He; Hu, Pu; Cui, Hao Source: Yantu Lixue/Rock and Soil Mechanics, v 28, n 11, November, 2007, p 2337-2342 Language: Chinese

ISSN: 1000-7598

Publisher: Academia Sinica

Abstract: The results of triaxial creep experiments for unloading state show that the frozen soil has an obvious dilatancy, and its volume strain should not be neglected. To fully reflect creep deformation laws of frozen soil under unloading state, a rheological constitutive dynamic model of frozen soil submitting to ellipse-DP two-yield-surface is put forward by using Nishihara model as the basic element. And the model is embedded in ADINA finite element program on the base of secondary developing technique for finite element program. The results of numerical simulation for triaxial creep experiments show that the constitutive dynamic model of ellipse-DP two-yield-surface can reflect some deformation properties of dilatancy and volume strain of frozen soil very well; and it can coincide with the experimental data, which can provide references for frozen projects calculation. (14 refs.)

Keywords:  Frozen soils  -  Constitutive models  -  Creep  -  Deformation  -  Dynamic models  -  Finite element method  -  Rheology  -  Strain

Secondary  Keywords:  Two yield surface model  -  Dilatancy  -  Volume strain  -  Numerical simulation  -  Creep deformation laws  -  ADINA finite element program

 


Studies on deformation mechanism and rock mass stability of high slopes of Geheyan Power Station under multiple factors

Li, Jian-Lin (College of Civil and Hydropower Engineering, China Three Gorges University); Liu, Jie; Wang, Le-Hua Source: Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering, v 29, n 9, September, 2007, p 1289-1295 Language: Chinese

ISSN: 1000-4548 CODEN: YGXUEB

Publisher: Chinese Society of Civil Engineering

Abstract: Through the finite elemental program of ADINA, a three-dimensional model of high slopes of Geheyan Power Station was established. Based on the unloading rock mass theory, the primary situation, excavation situation, unloading situation, reinforcement situation, sluice situation and creeping situation were considered. On the basis of the stress analysis and deformation analysis, the deformation theory and the stability of rock mass of the high slopes of Geheyan Power Station under the condition of several factors were studied. And then the function on distortion of the slopes were found. Compared with the monitoring results, the validity of analysis was proved, and further deformation of the high slopes was predicted. Meanwhile, some suggestions for the monitoring disposal based on the analytical results were given. (8 refs.)

Keywords:  Slope stability  -  Computer simulation  -  Creep  -  Deformation  -  Excavation  -  Finite element method  -  Hydroelectric power plants  -  Rock mechanics  -  Stress analysis

Secondary  Keywords:  Three dimensional model  -  Unloading rock mass theory  -  Deformation mechanism  -  ADINA  -  Geheyan power station  -  Primary situation  -  Excavation situation  -  Unloading situation  -  Reinforcement situation  -  Sluice situation  -  Creeping situation  -  Deformation analysis  -  Validity of analysis

 


Research on parabolic yield-surface creep constitutive model of artificial frozen soil

Li, Dong-Wei (Department of Civil Engineering, Anhui University of Science and Technology); Wang, Ren-He; Zhao, Yan-Hui; Hu, Pu Source: Yantu Lixue/Rock and Soil Mechanics, v 28, n 9, September, 2007, p 1943-1948 Language: Chinese

ISSN: 1000-7598

Publisher: Academia Sinica

Abstract: The triaxial creep experiment of artificial frozen soil in deep alluvium is performed by using self-developed a W3Z-200 apparatus of triaxial creep frozen soil. Analyzing the experiment results, applying parabolic yield criterion for improved viscoplasticity in the Nishihara model and coupling degree of temperature, a new creep constitutive model is established for describing frozen-soil's creep characteristics under the complicated stress state. The model is embedded in nonlinear ADINA finite element program in order to numerically analyze easily. Numerical simulation of the shaft well excavation process and field measurements of deformation of deep soil frozen wall are performed in Huainan Mine; and the results show that the established parabolic yield-surface constitutive model is correct and reasonable for FEM numerical simulation of deep soil frozen wall. (19 refs.)

Keywords:  Creep testing  -  Computer simulation  -  Constitutive models  -  Deformation  -  Excavation  -  Finite element method  -  Frozen soils  -  Temperature  -  Viscoplasticity

Secondary  Keywords:  Complex stress condition  -  Triaxial compressive creep  -  Parabolic yield surface  -  Artificial frozen soil  -  Triaxial creep experiment  -  Alluvium  -  W3Z 200 apparatus  -  Nishihara model  -  Coupling degree  -  ADINA  -  Numerical simulation  -  Shaft well

 


Numerical solution of elastic bodies in contact by FEM utilising equilibrium displacement fields

Frastia, Lubor (Department of Applied Mechanics, SjF, ZU) Source: Computational Mechanics, v 41, n 1, December, 2007, p 159-174

ISSN: 0178-7675 CODEN: CMMEEE

Publisher: Springer Verlag

Abstract: In this paper a new effective formulation of the computation of the statics of elastic bodies in contact is described and demonstrated. Line contact, plane strain, and negligible friction are assumed. The formulation is an extension of the standard finite element method (FEM). With the aim to utilise the Hertz theory directly, we use the exact solution of the elastic 2-dimensional halfspace loaded by Hertzian pressure distribution and enforce the contact condition by the method of Lagrange multipliers. In numerical examples we have focussed on the demonstration and evaluation of the accuracy of the new formulation for selected applications compared with the state of the art node-to-segment contact algorithm implemented in the software system ADINA. Proposed formulation is more accurate for problems where Hertz contact dominates the strain state, especially for small number of elements, whereas we obtained a fairly good agreement with ADINA for a more general bending problem. © 2007 Springer Verlag. (17 refs.)

Keywords:  Elasticity  -  Finite element method  -  Friction  -  Lagrange multipliers  -  Numerical methods  -  Pressure distribution  -  Static analysis  -  Strain

Secondary  Keywords:  Variational methods  -  Elastic bodies  -  Hertz theory

 


Improvement of local mechanical properties of concrete segment by steel-fiber reinforcement

Mo, Hai-Hong (School of Architecture and Civil Engineering, South China Univ. of Tech.); Chen, Jun-Sheng; Liang, Song; Yang, Yi-Bo; Su, Yi Source: Huanan Ligong Daxue Xuebao/Journal of South China University of Technology (Natural Science), v 35, n 7, July, 2007, p 116-121 Language: Chinese

ISSN: 1000-565X CODEN: HLDKEZ

Publisher: South China University of Technology

Abstract: In order to reveal the effect of steel-fiber reinforcement on the local mechanical properties of concrete segments used in shield tunnels, a general 3D finite element code, ADINA, was used to numerically analyze the cracking loads, stress distributions and crack distributions of the steel fiber-reinforced concrete (SFRC) segment under the jacking force or in a regular service stage. The results indicate that the addition of steel fibers can effectively improve the local mechanical properties of segment surface, hand holes and bolt holes, greatly enhance the anti-crack performance of SFRC segment, and make the first-crack load 13.3%-22.7% greater than that of the original reinforced concrete segment. (10 refs.)

Keywords:  Fiber reinforced materials  -  Cracking (chemical)  -  Reinforced concrete  -  Reinforcement

Secondary  Keywords:  Steel fiber  -  Shield tunnel  -  Segment  -  Mechanical property

 


Simulation of hot rolling of magnesium strip by using finite element technique

Shen, G. (Materials Technology Laboratory, CANMET); Essadiqi, E.; Galvani, C.; Spencer, K.; Elwazri, A.; Yue, S. Source: Magnesium Technology, Magnesium Technology 2007 - Proceedings of Symposium Sponsored by the Magnesium Committee of the Light Metals Division of TMS, 2007, p 59-68

ISSN: 1545-4150 ISBN-10: 0873396634

Conference: TMS 2007 Annual Meeting and Exhibition, Feb 25-Mar 1 2007, Orlando, FL, United States

Publisher: Minerals, Metals and Materials Society

Abstract: Finite element thermal and mechanical models were developed to simulate the thermal and mechanical behaviour of magnesium strip during hot rolling. The commercial finite element software ADINA-TMC was applied to couple the mechanical and thermal components iteratively. A number of processes important rolling parameters such as the roll speed, the dynamic contact between the roll and the strip, deformation-induced heating, friction on the contact surfaces, heat transfer both inside and between the strip and the roll have been simulated. The temperatures and stresses of the magnesium strips and the load applied on the strip for different rolling schedules were predicted. Comparisons of the predicted and experimental exit temperatures have been conducted for the magnesium alloy AZ31 for different combinations of rolling temperatures, reductions and rolling speeds. The difference between the predicted and measured exit temperatures is less than 3% in most situations. The predicted and measured values of load applied on the magnesium strip agree reasonably for 14 passes conducted with two different rolling speeds. The numerical model is used as a basis to discuss some important issues in hot rolling, such as the contribution of plastic work to the temperature change, effect of reduction rate on the effective heat transfer coefficient between the strip and roll, and the presence of residual stresses. (7 refs.)

Keywords:  Strip metal  -  Deformation  -  Finite element method  -  Friction  -  Hot rolling  -  Magnesium alloys  -  Residual stresses

Secondary  Keywords:  Magnesium strips  -  Rolling speeds  -  Temperature change

 


Restoring-force test of fiber-reinforced plasterboard with concrete core column

Jiang, Xin-Liang (School of Civil Engineering, Tianjin University); Gu, Yan Source: Tianjin Daxue Xuebao (Ziran Kexue yu Gongcheng Jishu Ban)/Journal of Tianjin University Science and Technology, v 40, n 5, May, 2007, p 542-547 Language: Chinese

ISSN: 0493-2137 CODEN: TCHHA9

Publisher: Tianjin University

Abstract: The restoring-force test of two fiber-reinforced plasterboards filled with concrete under horizontal cycle loading were carried out. Based on the experiments, the behavior of the damage state, the capacity of distortion and the ductility features were investigated. Testing results indicate that the concrete core and fiber-reinforced plasterboard work together to resist load effects, the earthquake energy is dissipated by the plasterboard cracking, and the seismic behavior and displacement ductility are increased. By using the finite element analysis program ADINA, the calculation model was set up to analyze the behavior of concrete core, fiber-reinforced plasterboard and the composite wall respectively. The results calculated by FEM are coincident with the testing ones, indicating that the FEM model is appropriate for this case. (8 refs.)

Keywords:  Columns (structural)  -  Composite materials  -  Ductility  -  Failure (mechanical)  -  Fiber reinforced materials  -  Finite element method  -  Loading  -  Strain measurement

Secondary  Keywords:  Fiber-reinforced plasterboard  -  Restoring force test  -  Damage feature  -  Distortion capacity

 


Using of laser ablation to fabrication nanocrystalline multilayer coatings for biomedical and tribological application

Major, Boguslaw (Institute of Metallurgy and Materials Science, Polish Academy of Sciences); Major, Roman; Lackner, Jurgen M.; Waldhauser, Wolfgang Source: Proceedings of SPIE - The International Society for Optical Engineering, v 6598, Laser Technology VIII: Applications of Lasers, 2007, p 659807

ISSN: 0277-786X CODEN: PSISDG

Conference: Laser Technology VIII: Applications of Lasers, Sep 25-29 2006, Szczecin-Swinoujscie, Poland Sponsor: SPIE Poland;Found. for the Dev. of the Szczecin Univ. of Technol., Poland

Publisher: SPIE -International Society for Optical Engineering

Abstract: Titanium nitride (TiN) is regarded as a potential biomaterial for blood-contact applications. TiN thin films were fabricated by pulsed laser deposition with the Nd:YAG laser on biologically applied polyurethane. Transmission electron microscopy (TEM) study of 350 nm thick films revealed columnar structure. Such films were observed to be brittle. In order to improve the coatings elasticity, the thickness was reduced to 50nm, which limited the deposition mechanism operation to the early stage. A biological test showed that TiN surface film produced on polyurethane is characterized by good biocompatibility and decreased surface affinity for cell adhesion. The physical explanation of TEM images was based on the performed finite element calculations of the temperature and stress distribution using the ADINA program. Boron nitride thin layers were produced by means of the pulsed laser deposition technique from hexagonal boron nitride target. Two types of laser i.e. Nd:YAG with Q-switch as well as KrF coupled with RF generator were used. Influence of deposition parameters on surface morphology, phase composition as well as mechanical properties is discussed. There are an increasing number of applications in tribology where the properties of a single material are not sufficient. One way to surmount this problem is to use a multilayer coating. Application of metallic interlayers improves adhesion of nitride hard layer in multilayer systems. Tribological coatings consisted of 4, 8 and 32 layers of Cr/CrN and Ti/TiN types were fabricated with the PLD technique. It is found in transmission electron examinations on thin foils prepared from cross-section that both nitride-based multilayer structures studied are characterized by small columnar crystallite sizes and high defect density, what might raise their hardness but compromise coating adhesion. The intermediate metallic layers contained larger sized and less defective columnar structure compared to the nitride layers, which should improve the coatings toughness. Switching from single layer to multi-layer metal/nitride composition improved resistance to delamination. (43 refs.)

Keywords:  Nanocrystalline materials  -  Biomedical engineering  -  Laser ablation  -  Neodymium lasers  -  Polyurethanes  -  Pulsed laser deposition  -  Titanium nitride  -  Transmission electron microscopy

Secondary  Keywords:  Columnar structure  -  Multilayer coatings  -  Tribological coatings

 

Time-Domain SSI Analysis of Typical Reactor Building using Frequency-Dependent Foundation Impedance Derived from SASSI

Mansour Tabatabaie, Basilio Sumodobila, and Thomas Ballard

SC Solutions, Inc., Oakland, CA

Transactions, SMiRT 19, 2007.

Abstract: In this paper we present a methodology for performing SSI analysis in time domain using distributed parameter foundation impedance (DPFI) model derived from SASSI analysis. First the foundation displacements and reaction forces in the x, y and z directions at each foundation interaction degree-of-freedom (DOF) are calculated from analysis of the total SSI system in frequency domain using SASSI. The results are then used to form matrix-valued, distributed foundation impedance (DFI) functions. In the second step, the resulting uncoupled, frequency-dependent DFI functions are linearized based on the response of a simple damped oscillator to develop the DPFI model. In the final step the DPFI model and scattered motions are incorporated in time-domain model of the structure using kinematic formulation. The accuracy of this procedure for the case of very stiff/rigid embedded foundation is demonstrated by analyzing the response of a typical pressurized water reactor (PWR) containment building subject to horizontal input motions. The comparison of results from one-step SASSI analysis of the total SSI system in frequency domain with those of ADINA analysis of the structure with DPFI model in time domain using direct integration method are presented and shown to be in good agreement.


Effect of Temperature on Tether Extraction, Surface Protrusion, and Cortical Tension of Human Neutrophils

Baoyu Liu, Craig J. Goergen, and Jin-Yu Shao

Department of Biomedical Engineering, Washington University, Saint Louis, Missouri

Biophysical Journal, 93:2923–2933, 2007.

Abstract: Neutrophil rolling on endothelial cells, the initial stage of its migrational journey to a site of inflammation, is facilitated by tether extraction and surface protrusion. Both phenomena have been studied extensively at room temperature, which is considerably lower than human body temperature. It is known that temperature greatly affects cellular mechanical properties such as viscosity. Therefore, we carried out tether extraction, surface protrusion, and cortical tension experiments at 37°C with the micropipette aspiration technique. The experimental temperature was elevated using a custom-designed microscope chamber for the micropipette aspiration technique. To evaluate the constant temperature assumption in our experiments, the temperature distribution in the whole chamber was computed with finite element simulation. Our simulation results showed that temperature variation around the location where our experiments were performed was less than 0.2°C. For tether extraction at 37°C, the threshold force required to pull a tether (40 pN) was not statistically different from the value at room temperature (51 pN), whereas the effective viscosity (0.75 pN.s/µm) decreased significantly from the value at room temperature (1.5 pN.s/µm). Surface protrusion, which was modeled as a linear deformation, had a slightly smaller spring constant at 37°C (40 pN/mm) than it did at room temperature (56 pN/µm). However, the cortical tension at 37°C (5.7 6 2.2 pN/µm) was substantially smaller than that at room temperature (23 6 8 pN/µm). These data clearly suggest that neutrophils roll differently at body temperature than they do at room temperature by having distinct mechanical responses to shear stress of blood flow.


Analytical and numerical solution for a elastic pipe bend at in-plane bending with consideration for the end effect

I.V. Orynyak, S.A. Radchenko

G.S. Pisarenko Institute for Problems of Strength, National Academy of Sciences of Ukraine, 2 Tymiryazevs’ka str., Kyiv, Ukraine

International Journal of Solids and Structures, 44:1488–1510, 2007.

Abstract: The authors proposed an analytical method for the analysis of the end effect in a pipe bend loaded by a bending moment with consideration for the action of internal pressure. The method is based on the use of simplifying hypotheses and is reduced to the solution of a system of fourth-order differential equations along the axial coordinate with respect to unknown coefficients in the expansion for tangential displacements. An approximate analytical solution, which has a trapezoidal structure and is written in terms of Krylov’s functions, has been obtained. Boundary conditions are formulated in terms of the tangential and longitudinal displacements and axial and shearing stress resultant. For the flexibility factor, analytical solutions are presented in the case where a bend is approximated by a rigid restraint on both ends. To verify the analytical solution and its applicability limits, two numerical procedures were developed, which are based on the finite difference method and the reduction to the Kochi problem by the expansion of the unknowns in the Fourier series over the circumferential coordinate. The authors compare the results obtained with data from the literature, discuss the advantages and disadvantages of the methods, and present recommendations for their practical application.

Keywords: Pipe bend – Shell - End effect - Analytical solution - Numerical procedure - Flexibility factor



Selective Vibrational Detachment of Microspheres Using Optically Excited In-Plane Motion of Nanomechanical Beams

B. Ilic1, S. Krylov2, M. Kondratovich3, and H. G. Craighead1

1School of Applied and Engineering Physics, Nanobiotechnology Center and Cornell Nanofabrication Facility, Cornell University, 250 Duffield Hall, Ithaca, New York 14853,
2School of Mechanical Engineering, Tel Aviv University 69978 Ramat Aviv, Israel,
3School of Mechanical and Aerospace Engineering and Cornell Nanoscale Facility, Cornell University, 250 Duffield Hall, Ithaca, New York 14853

Nano Lett., 7(8):2171-2177, 2007.

Abstract: Optical excitation plays an important role in the actuation of higher flexural and torsional modes of nanoelectromechanical oscillators. We show that optical fields are efficient for excitation, direct control, and measurement of in-plane motion of cantilever-type nanomechanical oscillators. As a model system, 200- and 250-nm-thick single-crystal silicon cantilevers with dissimilar lengths and widths ranging from 6 to 12 µm and 500 nm to 1 µm, respectively, were fabricated using surface micromachining and dynamically analyzed using optical excitation and interferrometric detection. Three-dimensional finite element analysis incorporating shear, rotational inertia, cross-sectional deplanation, and nonideal boundary conditions due to the structural undercut describe the dynamics of the nanomechanical structures adequately. The quality factor of a particular in-plane harmonic was consistently higher than the transverse mode. The increased dissipation of the out-of-plane mode was attributed to material and acoustic loss mechanisms. The in-plane mode was used to demonstrate vibrational detachment of submicrometer polystyrene spheres on the oscillator surface. In contrast, the out-of-plane motion, even in the strong nonlinear impact regime, was insufficient for the removal of bound polystyrene spheres. Our results suggest that optical excitation of in-plane mechanical modes provide a unique mechanism for controlled removal of particles bound on the surface of nanomechanical oscillators.


An alternative formulation of the Ritchie–Knott–Rice local fracture criterion

A. Neimitz, M. Graba, J. Galkiewicz

Kielce University of Technology, Al.1000 lecia P.P. 7, 25-314 Kielce, Poland

Engineering Fracture Mechanics, 74:1308–1322, 2007.

Abstract: In the paper an alternative formulation of the RKR local fracture criterion is proposed. It is based on the features of the stress distribution in front of a blunted crack in an elastic–plastic material. The stress distribution is computed using the finite strain option in the finite element method. It is postulated that the opening stress in front of the crack should be greater than the critical one, σc, over the distance llc, where lc is considered as a material parameter. The hypothesis is applied to estimate the influence of the in-plane constraint on fracture toughness. New formulas to compute the critical value of the J-integral are derived both for the small scale yielding and large plastic deformations in front of the crack. The results obtained are compared with the Sumpter and Forbes experimental results and with the O’Dowd analytical formula concerning the Jc = Jc(JIC,Q) relation.

Keywords: Local approach; In-plane constraint; RKR criterion

 



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