scholarly journals Analysis of Damage Models for Cortical Bone

2019 ◽  
Vol 9 (13) ◽  
pp. 2710
Author(s):  
Jacobo Baldonedo ◽  
José R. Fernández ◽  
José A. López-Campos ◽  
Abraham Segade
Keyword(s):  
Experimental Data ◽  
Mechanical Model ◽  
Bone Structure ◽  
Complex Structure ◽  
One Dimension ◽  
Two Dimensional ◽  
Qualitative Behaviour ◽  
Bone Implant ◽  
Damage Models ◽  
Good Agreement

Bone tissue is a material with a complex structure and mechanical properties. Diseases or even normal repetitive loads may cause microfractures to appear in the bone structure, leading to a deterioration of its properties. A better understanding of this phenomenon will lead to better predictions of bone fracture or bone-implant performance. In this work, the model proposed by Frémond and Nedjar in 1996 (initially for concrete structures) is numerically analyzed and compared against a bone specific mechanical model proposed by García et al. in 2009. The objective is to evaluate both models implemented with a finite element method. This will allow us to determine if the modified Frémond–Nedjar model is adequate for this purpose. We show that, in one dimension, both models show similar results, reproducing the qualitative behaviour of bone subjected to typical engineering tests. In particular, the Frémond–Nedjar model with the introduced modifications shows good agreement with experimental data. Finally, some two-dimensional results are also provided for the Frémond–Nedjar model to show its behaviour in the simulation of a real tensile test.

Design Methods of Volute Casings for Turbocharger Turbine Applications

1996 ◽  
Vol 210 (2) ◽  
pp. 149-156 ◽  
Author(s):  
H Chen
Keyword(s):  
Experimental Data ◽  
Potential Flow ◽  
Design Method ◽  
Three Dimensional ◽  
Design Methods ◽  
Two Dimensional ◽  
Aerodynamic Design ◽  
3D Design ◽  
Flow Equations ◽  
Good Agreement

This paper discusses aerodynamic design methods of volute casings used in turbocharger turbines. A quasi-three-dimensional (Q-3D) design method is proposed in which a group of extended two-dimensional potential flow equations and the streamline equation are numerically solved to obtain the geometry of spiral volutes. A tongue loss model, based on the turbulence wake theory, is also presented, and good agreement with experimental data is shown.

Study of viscosity on the fission dynamics of the excited nuclei 228U produced in 19F + 209Bi reactions

2015 ◽  
Vol 24 (07) ◽  
pp. 1550052 ◽  
Author(s):  
H. Eslamizadeh
Keyword(s):  
Experimental Data ◽  
Symmetry Axis ◽  
Measured Data ◽  
Total Spin ◽  
Langevin Equations ◽  
Two Dimensional ◽  
Excitation Energies ◽  
Fission Fragments ◽  
Excited Nuclei ◽  
Good Agreement

A two-dimensional (2D) dynamical model based on Langevin equations was applied to study the fission dynamics of the compound nuclei 228 U produced in 19 F + 209 Bi reactions at intermediate excitation energies. The distance between the centers of masses of the future fission fragments was used as the first dimension and the projection of the total spin of the compound nucleus onto the symmetry axis, K, was considered as the second dimension in Langevin dynamical calculations. The magnitude of post-saddle friction strength was inferred by fitting measured data on the average pre-scission neutron multiplicity for 228 U . It was shown that the results of calculations are in good agreement with the experimental data by using values of the post-saddle friction equal to 6–8 × 1021 s -1.

A mechanical model of creep of polycrystalline ice

1978 ◽  
Vol 15 (2) ◽  
pp. 155-170 ◽  
Author(s):  
Bernard Michel
Keyword(s):  
Experimental Data ◽  
Mechanical Model ◽  
Mathematical Expression ◽  
Two Dimensional ◽  
Elastic Deformations ◽  
Plastic Deformations ◽  
Creep Curves ◽  
Different Types ◽  
Polycrystalline Ice ◽  
Elastic And Plastic Deformations

The paper presents a two dimensional mechanical model for the deformation and creep of polycrystalline ice that takes into account the elastic and plastic deformations of each crystal.The model applies to many cases of creep so that the different types of creep curves have been defined during the transitory, permanent and accelerated phases and the corresponding creep laws have been derived. The mechanics of cracking are not analyzed in this paper.The expression for the plastic deformation in this model is based on the principle of multiplication of mobile dislocations and Glen's law for permanent creep. The corresponding mathematical expression for creep without cracking, called α creep, is shown to represent, at the lower limit, the flow of glaciers and is shown to verify a large variety of measured creep curves either in monocrystals or in polycrystalline ice.The elastic deformations in this model bring to light the important role played by delayed elasticity, which is shown by experimental data but has never been elucidated previously.

scholarly journals MODELING OF ELASTIC-PLASTIC DEFORMATION OF ELEMENTS OF SPATIAL STRUCTURES DURING PULSE INTERACTION WITH FLUID BASED ON THE GODUNOV'S METHOD OF INCREASED ACCURACY

2019 ◽  
Vol 81 (4) ◽  
pp. 488-499
Author(s):  
Wang Cheng ◽  
Yang Tonghui ◽  
Li Wan ◽  
Tao Li ◽  
M.H. Abuziarov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Shock Waves ◽  
Elastoplastic Deformation ◽  
Three Dimensional ◽  
Numerical Results ◽  
Two Dimensional ◽  
Wave Processes ◽  
Detonation Products ◽  
Comparison Of The Results ◽  
Good Agreement

The spatial problem of internal explosive loading of an elastoplastic cylindrical container filled with water in Eulerian - Lagrangian variables using multigrid algorithms is considered. A defining system of three-dimensional equations of the dynamics of gas, fluid, and elastoplastic medium is presented. For numerical modeling, a modification of S.K. Godunov scheme of the increased accuracy for both detonation products and liquids, and elastoplastic container is used. At the moving contact boundaries “detonation products - liquid”, “liquid - deformable body”, the exact solution of the Riemann's problem is used. A time dependent model is used to describe the propagation of steady-state detonation wave through an explosive from an initiation region. In both cases, the initiation of detonation occurs at the center of the charge. Two problems have been solved: the first task for the aisymmetric position of the charge, the second for the charge shifted relative to the axis of symmetry. In the first task, the processes are two-dimensional axisymmetric in nature, in the second task, the processes are essentially three-dimensional. A comparison is made of the results of calculations of the first problem using a three-dimensional method with a solution using a previously developed two-dimensional axisymmetric method and experimental data. Good agreement is observed between the numerical results for the maximum velocities and circumferential strains obtained by various methods and experimental data. There is good agreement between the numerical results obtained by various methods and the known experimental data. Comparison of the results of solving the first and second problems shows a significant effect of the position of the charge on the wave processes in the liquid, the processes of loading the container and its elastoplastic deformation. The dynamic behavior of a gas bubble with detonation products is analyzed. A significant deviation of the bubble shape from the spherical one, caused by the action of shock waves reflected from the structure, is shown. Comparison of the results of solving the first and second problems showed a significant effect of the charge position on wave processes in a liquid, the processes of loading a container and its elastoplastic deformation. In particular, in the second problem, shock waves of higher amplitude are observed in the liquid when reflected from the walls of the container.

On the swimming of a flexible plate of arbitrary finite thickness

1964 ◽  
Vol 20 (1) ◽  
pp. 1-33 ◽  
Author(s):  
J. P. Uldrick ◽  
J. Siekmann
Keyword(s):  
Experimental Data ◽  
Finite Thickness ◽  
Numerical Calculations ◽  
Flexible Plate ◽  
Two Dimensional ◽  
Present Contribution ◽  
Fish Propulsion ◽  
Special Cases ◽  
Good Agreement

This paper studies the effect of profile thickness on the propulsive forces generated by the swimming of a two-dimensional fish. Comparison of numerical calculations with reported experimental data shows good agreement and demonstrates a decrease of thrust with increasing thickness. Previous two-dimensional linearized theories on fish propulsion dealing with the motion of an infinitesimally thin hydrofoil are included in the present contribution as special cases.

Model Testing and CFD Analysis of 2D Profiles Towards Offshore Applications

2013 ◽  
Author(s):  
Lucas do Vale Machado ◽  
Antonio Carlos Fernandes ◽  
Gustavo César Rachid Bodstein
Keyword(s):  
Experimental Data ◽  
Experimental Measurements ◽  
Cfd Analysis ◽  
Two Dimensional ◽  
Reference Simulation ◽  
Sst Turbulence Model ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
Naca 0015 ◽  
Good Agreement

In this paper we present numerical and experimental work motivated by the study of a rudder profile with significant levels of lift that provides better performance for the maneuvering and stabilization of a ship. This is the so-called Schilling profile. The analysis of the two-dimensional subsonic steady flow over four profiles was carried out using computational fluid dynamics (CFD) tools with a κ-ω SST turbulence model. We consider three Schilling profiles with different thicknesses and the classical NACA 0015 profile, taken as a reference. Simulation results were compared to our experimental measurements at various angles of attack and two orders of magnitude of the Reynolds number, 5.45 × 104 and 1.09 × 105. The numerical results show general good agreement with experimental data and highlight the distinct behavior of Schilling profile.

Evaluation and Analysis of Curvature-Corrected Filter-based Turbulent Model

2017 ◽  
Vol 34 (3) ◽  
Author(s):  
Rui Zhang
Keyword(s):  
Experimental Data ◽  
Numerical Calculation ◽  
Correction Term ◽  
Two Dimensional ◽  
Turbulent Model ◽  
Engineering Applications ◽  
Streamline Curvature ◽  
Naca0012 Airfoil ◽  
Proposed Model ◽  
Good Agreement

AbstractPrediction of the characteristics of turbulent flow with streamline curvature is of great importance in engineering applications. In this paper, a curvature-corrected filter-based turbulent model is suggested by applying the Spalart-Shur correction term. This new version of the model (FBM-CC) has been tested and verified through two canonical benchmarks with strong streamline curvature: the flow in a two-dimensional U-duct and the free shear flow past NACA0012 airfoil with a round tip. Predictions of the FBM-CC model are compared with available experimental data and the corresponding results of the original FBM model. The numerical results show that the FBM-CC model significantly improves the sensitivity to the effect of streamline curvature and the numerical calculation accuracy, in relatively good agreement with the experimental data, which suggests that this proposed model may be employed to simulate the turbulent curved flow in engineering applications.

Complete Transient Two-Dimensional Analysis of Two-Phase Closed Thermosyphons Including the Falling Condensate Film

1994 ◽  
Vol 116 (2) ◽  
pp. 418-426 ◽  
Author(s):  
C. Harley ◽  
A. Faghri
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Conjugate Heat Transfer ◽  
Pipe Wall ◽  
Vapor Flow ◽  
Two Dimensional ◽  
Type Solution ◽  
Two Phase ◽  
Condensate Film ◽  
Good Agreement

A transient two-dimensional thermosyphon model is presented that accounts for conjugate heat transfer through the wall and the falling condensate film. The complete transient two-dimensional conservation equations are solved for the vapor flow and pipe wall, and the liquid film is modeled using a quasi-steady Nusselt-type solution. The model is verified by comparison with existing experimental data for a low-temperature thermosyphon with good agreement. A typical high-temperature thermosyphon was then simulated to examine the effects of vapor compressibility and conjugate heat transfer.

A Study of Shear-Spinnability of Metals

1961 ◽  
Vol 83 (4) ◽  
pp. 478-483 ◽  
Author(s):  
Serope Kalpakcioglu
Keyword(s):  
Experimental Data ◽  
Deformation Zone ◽  
Stress System ◽  
Two Dimensional ◽  
Maximum Reduction ◽  
State Of Stress ◽  
Analytical Work ◽  
Sine Law ◽  
Shear Spinning ◽  
Good Agreement

The deformation zone in shear-spinning is idealized for a two-dimensional process and maximum permissible thickness reduction without fracture is predicted in terms of the stress system in this zone. The effect of deviation from the sine law on the maximum reduction before fracture is shown analytically to be due to the influence of distortions of the unspun flange on the state of stress under the roller. The results of analytical work are compared with experimental data and good agreement has been obtained. The phenomenon of back extrusion in shear-spinning is shown to be the result of a compressive stress in the spun section parallel to the mandrel side and is greatly influenced by mandrel angle and deviation from the sine law.

scholarly journals Torque and buckling in stretched intertwined double-helix DNAs

2017 ◽  
Author(s):  
Sumitabha Brahmachari ◽  
John F. Marko
Keyword(s):  
Experimental Data ◽  
Mechanical Model ◽  
Double Helix ◽  
Magnetic Tweezers ◽  
Applied Force ◽  
Linking Number ◽  
Opposite Trend ◽  
Statistical Mechanical Model ◽  
Statistical Mechanical ◽  
Good Agreement

We present a statistical-mechanical model for the behavior of intertwined DNAs, with a focus on their torque and extension as a function of their catenation (linking) number and applied force, as studied in magnetic tweezers experiments. Our model produces results in good agreement with available experimental data, and predicts a catenation-dependent effective twist modulus distinct from what is observed for twisted individual double-helix DNAs. We find that buckling occurs near to the point where experiments have observed a kink in the extension versus linking number, and that the subsequent “supercoiled braid” state corresponds to a proliferation of multiple small plectoneme structures. We predict a discontinuity in extension at the buckling transition corresponding to nucleation of the first plectoneme domain. We also find that buckling occurs for lower linking number at lower salt; the opposite trend is observed for supercoiled single DNAs.

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