Using multi-dimensional contact mechanics experiments to measure Poisson's ratio of porous low-k films

2003 ◽  
Vol 766 ◽  
Author(s):  
B. N. Lucas ◽  
J. C. Hay ◽  
W. C. Oliver
Keyword(s):  
Integrated Circuits ◽  
Contact Mechanics ◽  
Poisson’S Ratio ◽  
Mechanical Response ◽  
Contact Stiffness ◽  
Poisson's Ratio ◽  
Elastic Behavior ◽  
Structural Effects ◽  
Potential Influence ◽  
Low K

AbstractUsing a new multi-dimensional contact mechanics system, it was recently shown that the experimentally measured tangential to normal stiffness ratio of a contact can be described as a function of the bulk Poisson's ratio of the material as predicted by Mindlin [1-3]. This system has been utilized to measure the normal and tangential elastic contact stiffness of a series of porous low-k films, with increasing starting porogen content. These results indicate a transition from a material-controlled elastic behavior to a structure-controlled elastic behavior as the porosity of the film is increased. These structural effects and their potential influence on the mechanical response to forces imposed on integrated circuits are discussed. The experimental details and apparatus are introduced and described.

scholarly journals A Hybrid Artificial Intelligence Model to Predict the Elastic Behavior of Sandstone Rocks

2019 ◽  
Vol 11 (19) ◽  
pp. 5283 ◽  
Author(s):  
Gowida ◽  
Moussa ◽  
Elkatatny ◽  
Ali
Keyword(s):  
Poisson’S Ratio ◽  
Accurate Determination ◽  
Oil And Gas Industry ◽  
Poisson's Ratio ◽  
Elastic Behavior ◽  
Percentage Error ◽  
Ann Model ◽  
Field Development ◽  
Well Completion

Rock mechanical properties play a key role in the optimization process of engineering practices in the oil and gas industry so that better field development decisions can be made. Estimation of these properties is central in well placement, drilling programs, and well completion design. The elastic behavior of rocks can be studied by determining two main parameters: Young’s modulus and Poisson’s ratio. Accurate determination of the Poisson’s ratio helps to estimate the in-situ horizontal stresses and in turn, avoid many critical problems which interrupt drilling operations, such as pipe sticking and wellbore instability issues. Accurate Poisson’s ratio values can be experimentally determined using retrieved core samples under simulated in-situ downhole conditions. However, this technique is time-consuming and economically ineffective, requiring the development of a more effective technique. This study has developed a new generalized model to estimate static Poisson’s ratio values of sandstone rocks using a supervised artificial neural network (ANN). The developed ANN model uses well log data such as bulk density and sonic log as the input parameters to target static Poisson’s ratio values as outputs. Subsequently, the developed ANN model was transformed into a more practical and easier to use white-box mode using an ANN-based empirical equation. Core data (692 data points) and their corresponding petrophysical data were used to train and test the ANN model. The self-adaptive differential evolution (SADE) algorithm was used to fine-tune the parameters of the ANN model to obtain the most accurate results in terms of the highest correlation coefficient (R) and the lowest mean absolute percentage error (MAPE). The results obtained from the optimized ANN model show an excellent agreement with the laboratory measured static Poisson’s ratio, confirming the high accuracy of the developed model. A comparison of the developed ANN-based empirical correlation with the previously developed approaches demonstrates the superiority of the developed correlation in predicting static Poisson’s ratio values with the highest R and the lowest MAPE. The developed correlation performs in a manner far superior to other approaches when validated against unseen field data. The developed ANN-based mathematical model can be used as a robust tool to estimate static Poisson’s ratio without the need to run the ANN model.

Determination of Poisson's Ratio of Thin low-k Films using Bidirectional Thermal Expansion Measurement

2006 ◽  
Vol 914 ◽  
Author(s):  
Jiping Ye ◽  
Satoshi Shimizu ◽  
Shigeo Sato ◽  
Nobuo Kojima ◽  
Junnji Noro
Keyword(s):  
Thermal Expansion ◽  
Temperature Gradient ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Silicon Oxide ◽  
Young's Modulus ◽  
Polymer Materials ◽  
Poisson's Ratio ◽  
Thermal Expansion Measurement ◽  
Low K

AbstractA recently developed bidirectional thermal expansion measurement (BTEM) method was applied to different types of low-k films to substantiate the reliability of the Poisson's ratio found with this technique and thereby to corroborate its practical utility. In this work, the Poisson's ratio was determined by obtaining the temperature gradient of the biaxial thermal stress from substrate curvature measurements, the temperature gradient of the whole thermal expansion strain along the film thickness from x-ray reflectivity (XRR) measurements, and reduced modulus of the film from nanoindentation measurements. For silicon oxide-based SiOC film having a thickness of 382.5 nm, the Poisson's ratio, Young's modulus and thermal extension coefficient (TEC) were determined to be Vf = 0.26, αf =21 ppm/K and Ef =9,7 GPa. These data are close to the levels of metals and polymers rather than the levels of fused silicon oxide, which is characterized by Vf = 0.17 and Er = 69.6 GPa. The alkyl component in the silicon oxide-based framework is thought to act as an agent in reducing the modulus and elevating the Poisson's ratio in SiOC low-k materials. In the case of an organic polymer SiLK film with a thickness of 501.5 nm, the Poisson's ratio, Young's modulus and TEC were determined to be Vf = 0.39, αf =74 ppm/K and Er =3.1 GPa, which are in the typical range of V= 0.34~0.47 with E =1.0~10 GPa for polymer materials. From the viewpoint of the relationship between the Poisson's ratio and Young's modulus as classified by different material types, the Poisson's ratios found for the silicon oxide-based SiOC and organic SiLK films are reasonable values, thereby confirming that BTEM is a reliable and effective method for evaluating the Poisson's ratio of thin films.

Metamaterials with enhanced mechanical properties and tuneable Poisson’s ratio

2021 ◽  
Author(s):  
Amer Alomarah ◽  
Syed Masood ◽  
Dong Ruan
Keyword(s):  
Poisson’S Ratio ◽  
Structural Modification ◽  
Mechanical Response ◽  
Good Alternative ◽  
Poisson's Ratio ◽  
Polyamide 12 ◽  
Loading Direction ◽  
Wide Range ◽  
Potential Applications ◽  
Parametric Studies

Abstract This paper reports a structural modification of an auxetic metamaterial with a combination of representative re-entrant and chiral topologies, namely, a re-entrant chiral auxetic (RCA). The main driving force for the structural modification was to overcome the undesirable properties of the RCA metamaterial such as anisotropic mechanical response under uniaxial compression. Additively manufactured polyamide 12 specimens via Multi Jet Fusion (MJF) were quasi-statically compressed along the two in-plane directions. The experimental results confirmed that the modified structure was less sensitive to the loading direction and the deformation was more uniform. Moreover, similar energy absorptions were obtained when the modified metamaterial was crushed along the two in-plane directions. The energy absorptions were improved from 390 to 950 kJ/m³ and from 500 to 1000 kJ/m³ compared with the RCA when they were crushed along the X and Y directions, respectively. The absorbed energy per unit mass (SEA) also improved from 1.4 to 2.9 J/g and from 1.78 to 3.1 J/g compared with that of the RCA under the axial compression along the X and Y directions. Furthermore, parametric studies were performed and the effects of geometric parameters of the modified metamaterial were numerically investigated. Tuneable auxetic feature was obtained. The energy absorption and Poisson’s ratio of the modified metamaterial offer it a good alternative for a wide range of potential applications in the areas such as aerospace, automotive, and human protective equipment.

scholarly journals Promising Bialkali Bismuthides Cs(Na, K)2Bi for High-Performance Nanoscale Electromechanical Devices: Prediction of Mechanical and Anisotropic Elastic Properties under Hydrostatic Tension and Compression and Tunable Auxetic Properties

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2739
Author(s):  
Shahram Yalameha ◽  
Zahra Nourbakhsh ◽  
Ali Ramazani ◽  
Daryoosh Vashaee
Keyword(s):  
Elastic Properties ◽  
Poisson’S Ratio ◽  
High Performance ◽  
Hydrostatic Compression ◽  
Poisson's Ratio ◽  
Elastic Behavior ◽  
Hydrostatic Tension ◽  
Tension And Compression ◽  
Electromechanical Devices ◽  
Anisotropic Elastic

Using first-principles calculations, we predict highly stable cubic bialkali bismuthides Cs(Na, K)2Bi with several technologically important mechanical and anisotropic elastic properties. We investigate the mechanical and anisotropic elastic properties under hydrostatic tension and compression. At zero pressure, CsK2Bi is characterized by elastic anisotropy with maximum and minimum stiffness along the directions of [111] and [100], respectively. Unlike CsK2Bi, CsNa2Bi exhibits almost isotropic elastic behavior at zero pressure. We found that hydrostatic tension and compression change the isotropic and anisotropic mechanical responses of these compounds. Moreover, the auxetic nature of the CsK2Bi compound is tunable under pressure. This compound transforms into a material with a positive Poisson’s ratio under hydrostatic compression, while it holds a large negative Poisson’s ratio of about −0.45 along the [111] direction under hydrostatic tension. An auxetic nature is not observed in CsNa2Bi, and Poisson’s ratio shows completely isotropic behavior under hydrostatic compression. A directional elastic wave velocity analysis shows that hydrostatic pressure effectively changes the propagation pattern of the elastic waves of both compounds and switches the directions of propagation. Cohesive energy, phonon dispersion, and Born–Huang conditions show that these compounds are thermodynamically, mechanically, and dynamically stable, confirming the practical feasibility of their synthesis. The identified mechanisms for controlling the auxetic and anisotropic elastic behavior of these compounds offer a vital feature for designing and developing high-performance nanoscale electromechanical devices.

The Effects of Dimension Ratio on the Micropolar Peridynamic Model

2010 ◽  
Author(s):  
Y. Ferhat ◽  
I. Ozkol
Keyword(s):  
Finite Element ◽  
Finite Element Methods ◽  
Displacement Field ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Elastic Behavior ◽  
Displacement Fields ◽  
Peridynamic Theory ◽  
Peridynamic Model ◽  
Central Forces

The aim of this study is to investigate the capability of the micropolar peridynamic theory to analyze elastic behavior of plates with various length and width. Since the quantities such as stress and strain are related to displacement field, only the displacement fields of these structures are computed using the micropolar peridynamic model while Poisson’s ratios are kept constant. The results are compared both to the analytical solution of the classical elasticity theory and to the solution of displacement based finite element methods. The software package ANSYS is used for FEM results. To compute the displacement field, a programming code is developed using MATHEMATICA. In the peridynamic theory the constitutive model contains only central forces and can be applied only to the materials having 1/4 Poisson’s ratio. It is the biggest shortcoming of the peridynamic theory. To overcome strict Poisson’s ratio limitation of the peridynamic theory, the micropolar peridynamic theory is proposed. The micropolar peridynamic model allows peridynamic moments, in addition to peridynamic central forces, to interact with the particles inside the material horizon. The introduction of the moments to the theory allows us to deal with the materials having Poisson’s ratio different from 1/4. This modification can be seen as the generalization of the peridynamic theory. Furthermore, the micropolar peridynamic theory can be easily implemented using the finite element methods. This provides easy application of the boundary conditions to the physical model in hand. In this work, by applying the micropolar peridynamic theory, we observed that the displacement fields of the plates are strongly affected by dimensional ratio of the plates. However, it is naturally expected that the micropolar and classical theories should give the same results, at least to a certain extend. This strong dependability on the dimensions of the structure can be a significant shortcoming of the micropolar peridynamic theory.

The effect of large deformation on Poisson’s ratio of brain white matter: An experimental study

2020 ◽  
pp. 095441192098402
Author(s):  
Faezeh Eskandari ◽  
Zahra Rahmani ◽  
Mehdi Shafieian
Keyword(s):  
Brain Tissue ◽  
Poisson’S Ratio ◽  
Computational Models ◽  
Mechanical Response ◽  
Incompressible Material ◽  
Material Behavior ◽  
Poisson's Ratio ◽  
Unconfined Compression ◽  
Injury Threshold ◽  
Brain White Matter

A more Accurate description of the mechanical behavior of brain tissue could improve the results of computational models. While most studies have assumed brain tissue as an incompressible material with constant Poisson’s ratio of almost 0.5 and constructed their modeling approach according to this assumption, the relationship between this ratio and levels of applied strains has not yet been studied. Since the mechanical response of the tissue is highly sensitive to the value of Poisson’s ratio, this study was designed to investigate the characteristics of the Poisson’s ratio of brain tissue at different levels of applied strains. Samples were extracted from bovine brain tissue and tested under unconfined compression at strain values of 5%, 10%, and 30%. Using an image processing method, the axial and transverse strains were measured over a 60-s period to calculate the Poisson’s ratio for each sample. The results of this study showed that the Poisson’s ratio of brain tissue at strain levels of 5% and 10% was close to 0.5, and assuming brain tissue as an incompressible material is a valid assumption at these levels of strain. For samples under 30% compression, this ratio was higher than 0.5, which could suggest that under strains higher than the brain injury threshold (approximately 18%), tissue integrity was impaired. Based on these observations, it could be concluded that for strain levels higher than the injury threshold, brain tissue could not be assumed as an incompressible material, and new material models need to be proposed to predict the material behavior of the tissue. In addition, the results showed that brain tissue under unconfined compression uniformly stretched in the transverse direction, and the bulging in the samples is negligible.

scholarly journals Structural deformation and mechanical response of CrS2, CrSe2 and Janus CrSSe

2021 ◽  
Author(s):  
Shambhu Bhandari Sharma ◽  
Ramesh Paudel ◽  
Rajendra Adhikari ◽  
Gopi Chandra Kaphle ◽  
Durga Paudyal
Keyword(s):  
Poisson’S Ratio ◽  
Density Functional ◽  
Tensile Strain ◽  
Mechanical Response ◽  
Axial Stress ◽  
Covalent Bond ◽  
Poisson's Ratio ◽  
Structural Deformation ◽  
Plastic Behavior ◽  
Potential Candidate

In the framework of density functional theory (DFT), we investigate the structural deformation, and mechanical behavior of the Janus CrSSe, which has out-of-plane structural asymmetry, with conventional transition metal dichalcogenides (TMDs) CrS2 and CrSe2 . The Janus CrSSe could be a potential candidate for machinable optoelectronic and piezoelectric applications. We predict that these compounds are chemically, mechanically, and dynamically stable with the covalent bond between the TM(Cr) and chalcogen(X=S, Se) atoms. Due to the influence of tensile strain, the Cr-X bond length of each monolayers increases, and the thickness decreases. Interestingly, the in-plane stiffness, shear and layer moduli, Poisson’s ratio, ultimate bi/uni-axial stress of Janus CrSSe are in between the values of CrS2 and CrSe2 monolayers. Similar to TMDs, the orientation-dependent in-plane stiffness and Poisson’s ratio demonstrate the isotropic behavior in Janus CrSSe. Furthermore, it can sustain a larger value of uni/bi-axial tensile strain with the critical strain equivalent to CrX2 monolayers. By applying higher-order strain, we have also found average elastic-plastic behavior as expected. These findings demonstrate that the Janus CrSSe monolayer is a mechanically stable and ductile compound that maintains the hybrid behavior.

Effect of Negative Poisson's Ratios of Auxetic UHMWPE on the Contact Mechanics in Artificial Hip Joint Replacement

2011 ◽  
Vol 399-401 ◽  
pp. 1559-1563
Author(s):  
Fang Xie ◽  
Zuo Min Liu
Keyword(s):  
Contact Mechanics ◽  
Hip Joint ◽  
Joint Replacement ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Unusual Property ◽  
Hip Joint Replacement ◽  
Artificial Hip Joint ◽  
Artificial Hip ◽  
Poisson's Ratios

With the development of functional and structural materials, increasing interests have been shown in the field of biomaterials with a negative Poisson’s ratio (auxetic), which exhibit the unusual property of becoming thinner when compressed. This unusual property makes it potentially a synthetic replacement biomaterial with adequate mechanical property and wear resistance. In this study, the potential of applying the auxetic ultra-high molecular weight polyethylene (UHMWPE) for the artificial hip joint was discussed. The contact mechanics characteristics in artificial hip joint replacement under different Poisson's ratios of -1<μ≤0.5 were investigated and compared using the finite element method. The results show that Poisson’s ratio had great effect on the contact mechanics in artificial hip joint replacement. Therefore, the future work should focus on tailoring an auxetic UHMWPE with a suitable Poisson’s ratio for artificial hip joint replacements.

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