scholarly journals Analysis of the Elasto-Plastic Response of a Polygonal Packing

2002 ◽  
Author(s):  
Fernando Alonso Marroqui´n ◽  
Hans Herrmann ◽  
Stefan Luding
Keyword(s):  
Poisson Ratio ◽  
Young Modulus ◽  
Dynamics Simulation ◽  
Elastic Response ◽  
Additional Parameter ◽  
Plastic Response ◽  
Plastic Deformations ◽  
Elastic Regime ◽  
Constitutive Response ◽  
Flow Directions

We investigate the constitutive response of two-dimensional packed samples of polygons using molecular dynamics simulation. The incremental elasto-plastic response is examined in the pre-failure regime. Besides the Young modulus and the Poisson ratio, an additional parameter must be included, which takes into account the anisotropy of the elastic response. The plastic deformations are described by the introduction of the yield and the flow directions. These directions do not agree, which reproduces the non-associated feature of realistic soils. In order to detect the yield surface, different loading-unloading-reloading tests were performed. During the reload path, it is found that the yielding develops continuously with the amplitude of loading, which does not allow to identify a purely elastic regime.

Comparison of the viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate)

1979 ◽  
Vol 44 (6) ◽  
pp. 1942-1948 ◽  
Author(s):  
Jaroslav Hrouz ◽  
Michal Ilavský ◽  
Ivan Havlíček ◽  
Karel Dušek
Keyword(s):  
Methyl Acrylate ◽  
Poisson Ratio ◽  
Young Modulus ◽  
Ethyl Acrylate ◽  
Sample Volume ◽  
Viscoelastic Behaviour ◽  
Tensile Behaviour ◽  
Temperature Superposition ◽  
Main Transition

The viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate) in the main transition region have been investigated. It was found that the time-temperature superposition could be carried out in the case of the penetration viscoelastic behaviour; the temperature dependence of the penetration and tensile shift factors was the same. The superimposed curves of the penetration and Young modulus allowed us to calculate the dependence of the Poisson ratio and thus to characterize the change in sample volume with deformation. It was demonstrated that the penetration method of determination of the viscoelastic behaviour is equivalent to the tensile method.

Effect of Size on the Mechanical Properties of Rh-20at%Pd Nanowire

2011 ◽  
Vol 403-408 ◽  
pp. 1173-1177
Author(s):  
Jamal Davoodi ◽  
Mohammad Javad Moradi
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
Constant Pressure ◽  
Young Modulus ◽  
Dynamics Simulation ◽  
Many Body ◽  
Temperature Constant ◽  
Body Potential

The aim of this research was to calculate Yong modulus, Bulk modulus and the elastic constants of Rh-20at%Pd (atom percent) nanowire. The molecular dynamics simulation technique was used to calculate the mechanical properties at constant temperature, constant pressure ensemble. The cohesive energy of the model nanowire systems was calculated by Quantum Sutton-Chen many body potential. The temperature and the pressure of the system were controlled by Nose-Hoover thermostat and Berendsen barostat, respectivly. In addition effects of the diameter of nanowire on the mechanical properties were studied. The obtained results show that, when the diameter of Rh-Pd nanowire increase, elastic constants, bulk modulus and Young modulus all increase, and when the diameter reaches about 5.5 nm, the properties began to level off and remain constant.

Young modulus and Poisson ratio measurements of TiO2 thin films deposited with Atomic Layer Deposition

2012 ◽  
Vol 206 (8-9) ◽  
pp. 2459-2463 ◽  
Author(s):  
L. Borgese ◽  
M. Gelfi ◽  
E. Bontempi ◽  
P. Goudeau ◽  
G. Geandier ◽  
...  
Keyword(s):  
Thin Films ◽  
Atomic Layer Deposition ◽  
Poisson Ratio ◽  
Young Modulus ◽  
Atomic Layer ◽  
Tio2 Thin Films ◽  
Layer Deposition

Biomechanical Properties of the Human Soft Palate

2009 ◽  
Vol 46 (3) ◽  
pp. 268-274 ◽  
Author(s):  
M. J. Birch ◽  
P. D. Srodon
Keyword(s):  
Soft Palate ◽  
Ex Vivo ◽  
Poisson Ratio ◽  
Young Modulus ◽  
Physiological Saline ◽  
Free Edge ◽  
Biomechanical Properties ◽  
Lateral Direction ◽  
The Mean ◽  
Viscoelastic Constants

Objective: To measure biomechanical properties of the human soft palate and the variation across anatomic regions. Design: Ex vivo analysis of human tissue. Patients/participants: Ten palates harvested from 10 normal adult human cadavers (age range, 37 to 90 years). Interventions: Computer-controlled uniaxial stress-relaxation mechanical properties tested in physiological saline at 37°C. Main Outcome Measures: Measurement of Young modulus, Poisson ratio, and determination of viscoelastic constants c, τ1, and τ2 by curve-fitting of the reduced relaxation function to the data. Results: One hundred sections were tested from the 10 palates, representative of 10 anatomic zones. The mean Young modulus range was 585 Pa at the posterior free edge to 1409 Pa at regions of attachment. The mean Poisson ratio in the inferior-superior direction was 0.45 (SD 0.26) and in the lateral direction, was 0.30 (SD 0.21). The mean viscoelastic constants for 1-mm extensions were C  =  −0.1056 (±0.1303), τ1  =  11.0369 (±9.1865) seconds, and τ2  =  0.2128 (±0.0792) seconds, and for 2-mm extensions were C  =  −0.1111 (±0.1466), τ1  =  14.3725 (±5.2701) seconds, and τ2  =  0.2094 (±0.0544) seconds. Conclusions: The results show agreement with values of the Young modulus estimated by authors (Ettema and Kuehn, 1994; Berry et al., 1999) undertaking finite element modeling of the palate. However, other modulus measurements based on closing pressure are considerably different. The spatial distribution of viscoelastic parameters across the palate shows good consistency.

scholarly journals Spherical Indentation of a Micropolar Solid: A Numerical Investigation Using the Local Point Interpolation–Boundary Element Method

2021 ◽  
Vol 2 (3) ◽  
pp. 581-590
Author(s):  
Gaël Pierson ◽  
M’Barek Taghite ◽  
Pierre Bravetti ◽  
Richard Kouitat Njiwa
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Interpolation Method ◽  
Poisson Ratio ◽  
Young Modulus ◽  
Contact Radius ◽  
Spherical Indentation ◽  
Local Point ◽  
Point Interpolation ◽  
Element Method

The load-penetration curve in elastic nanoindentation of an elastic micropolar flat by a diamond spherical punch is analyzed. The presented results are obtained by a specifically developed numerical tool based on a judicious combination of the conventional boundary element method and strong form local point interpolation method. The results show that the usual linear relationship between the material depression and the square of the radius of the contact area is also valid in this case of micropolar elastic material. It is also shown that the relation between the indentation stress (applied load over the contact surface) and the indentation strain (ratio of contact radius by the punch radius) is linear. The proportionality coefficient which is none other than the indentation stiffness varies with the coupling factor of the micropolar elastic medium. A relation between the indentation stiffness of a micropolar solid and that of a conventional solid with the same Young modulus and Poisson ratio is derived.

Effects of the Presence of Multiple Spherical Inclusions Within an Elastic Half-Space in a Circular Point Contact

2010 ◽  
Author(s):  
D. Ne´lias ◽  
J. Leroux ◽  
B. Fulleringer
Keyword(s):  
Poisson Ratio ◽  
Computing Time ◽  
Point Contact ◽  
Homogeneous Solution ◽  
Young Modulus ◽  
Contact Problems ◽  
Fast Method ◽  
Equivalent Inclusion Method ◽  
Computation Efficiency ◽  
Spherical Inclusions

A fast method to solve contact problems when one of the mating bodies contains multiple heterogeneous inclusions is proposed, and numerical results are presented for soft or stiff inhomogeneities. The emphasis is put on the effects of spherical inclusions on the contact pressure distribution. The computing time and allocated memory are kept small, compared to the finite element method, by the use of analytical solution to account for the presence of inhomogeneities. The Eshelby’s equivalent inclusion method is considered in the contact solver. An iterative process is implemented to determine the displacements and stress fields caused by the eigenstrains of all spherical inclusions. The proposed method can be seen as an enrichment technique for which the effect of heterogeneous inclusions is superimposed to the homogeneous solution in the contact algorithm. 3D and 2D FFT are utilized to improve the computation efficiency. Configurations such as stringer and cluster of spherical inclusions are analyzed. The effects of the Young modulus, Poisson ratio, size and location of the inhomogeneities are also investigated.

Experience of using seismoacoustic methods for a detailed modeling of geological environment at design of high criticallity objects of nuclear construction

2019 ◽  
Vol 12 (11-12) ◽  
pp. 52-62
Author(s):  
I. V. Galushkin ◽  
N. A. Ragozin ◽  
D. V. Stenin ◽  
V. I. Ignatev
Keyword(s):  
Cross Sections ◽  
Nuclear Power ◽  
Poisson Ratio ◽  
Young Modulus ◽  
Environmental Parameters ◽  
Cone Penetration ◽  
Reflected Waves ◽  
Use Of Data ◽  
Geological Cross Section ◽  
Seismic Records

Engineering surveys for the design of facilities with high criticality rating require a switch from methods with discrete assessment of environmental parameters (drilling and static / dynamic sounding), to methods that allow to obtain these values continuously in а massif. The most efficient way to solve this problem is by performing crosshole seismic tomography (CST). The article presents the results of CST during geophysical studies at the site of projected nuclear power plant (NPP). Four cross sections were obtained as a result of survey at distances from 24 to35 metersbetween the boreholes. Requirements for the boreholes preparation are specified in article, along with description of equipment for seismic signals excitation and registration, the examples of seismic records (gathers), methods of analysis and data processing are also shown. The velocity sections for compressional and shear waves obtained as a result of tomographic inversion are presented. The values of dynamic characteristics of soil properties (Young modulus, shear modulus, Poisson ratio) and their distribution in the inter-well space were calculated with the use of data on the soil density of the massif. Also, the article shows the result of applying the technique of incident and reflected waves fields allocation, which were obtained as a result of seismic cone penetration test (SCPT) to depths of 20–30 meters aiming to get detailed geological cross-section.

Large Deformation Analysis of an Elastic-Plastic Cantilevered Beam

1989 ◽  
Vol 111 (3) ◽  
pp. 312-315 ◽  
Author(s):  
D. W. Nicholson
Keyword(s):  
Large Deformation ◽  
Numerical Procedure ◽  
Bending Moment ◽  
Elastic Response ◽  
Graphical Form ◽  
Deformation Analysis ◽  
Plastic Response ◽  
Large Deformation Analysis ◽  
Elastic Plastic ◽  
Cantilevered Beam

This study concerns the analysis of the deflection of an elastic-plastic cantilevered beam. Three regions of solution are treated: (i) purely elastic response at low loads; (ii) elastic-plastic response without a hinge, for intermediate loads; and (iii) elastic-plastic response with a hinge for loads corresponding to the fully plastic bending moment at the built-in end. Most existing solutions for this type of problem involve various approximations avoided here, for example, ignoring the elastic part of the strain or using upper bounds based on limit analysis. By avoiding such approximations, the solution given here may be useful as a benchmark for validating finite element codes in the large deformation elastic-plastic regime. Several aspects of the solution are analyzed: (i) the load-deflection relation; (ii) the growth of the elastic-plastic zone; (iii) limiting cases; (iv) the residual configuration; (v) the small bending configuration. A numerical procedure based on Runge-Kutta methods is used, leading to the load-deflection relation in graphical form.

Mathematical Modeling of Noninvasive Blood Pressure Estimation Techniques—Part I: Pressure Transmission Across the Arm Tissue

1995 ◽  
Vol 117 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Mauro Ursino ◽  
Cristina Cristalli
Keyword(s):  
Blood Pressure ◽  
Poisson Ratio ◽  
Young Modulus ◽  
External Pressure ◽  
Noninvasive Blood Pressure ◽  
Estimation Techniques ◽  
External Pressures ◽  
Pressure Transmission ◽  
Pressure Estimation ◽  
Blood Pressure Estimation

A mathematical model of the arm tissue mechanical behavior under the effect of external pressure loads is presented. The model has been used to study stress and strain distribution across the tissue, and pressure transmission to the brachial artery, when the arm is compressed by two adjacent cuffs independently inflated. Using this configuration, the tissue elastic parameters (Young modulus and Poisson ratio) can be individually identified using a simple and noninvasive experimental procedure. Model validation has been achieved by comparing its results with data obtained experimentally on 10 subjects. These comparisons demonstrate that the proposed model may constitute a simple but valid new tool able to describe tissue behavior, subjected to external pressures, with sufficient accuracy. Joined with a model of brachial hemodynamics, it might contribute to improve our understanding of noninvasive blood pressure estimation techniques.

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