scholarly journals A Simple Energy-based Approach of Stent Elastic Properties

2020 ◽  
Vol 319 ◽  
pp. 02002
Author(s):  
Shuai Wang ◽  
Kaifa Zhou ◽  
Zhong Li
Keyword(s):  
Energy Conservation ◽  
Young’S Modulus ◽  
Elastic Moduli ◽  
Young's Modulus ◽  
Cell Structure ◽  
Beam Theory ◽  
Numerical Data ◽  
Grid Structure ◽  
Element Analysis ◽  
Energy Conservation Principle

Simple closed-form expressions were derived for the elastic moduli of lozenge grid structure based on the convenient beam theory and energy conservation principle. Finite element analysis was employed to validate the analytical estimates of the Young’s modulus. The theoretic results were also compared with the numerical data in the literature. The results show that the calculation method of Young’s modulus obtained by energy conservation is feasible, which provides a new way for stress analysis of sandwich structures. At the same time, the cell structure proposed in this paper provides a new scheme for the design of vascular stent.

Reduction In Young's Modulus Of Aluminum Foams Due To Cell Wall Curvature And Corrugation

1998 ◽  
Vol 521 ◽  
Author(s):  
W. Sanders ◽  
L. J. Gibson
Keyword(s):  
Compressive Strength ◽  
Cell Wall ◽  
Young’S Modulus ◽  
Cell Walls ◽  
Young's Modulus ◽  
Cell Structure ◽  
Microstructural Characterization ◽  
Aluminum Foams ◽  
Element Analysis ◽  
Simple Bounds

ABSTRACTMeasurements of the Young's modulus and compressive strength of several closedcell aluminum foams indicate that they are lower than expected from models for foam behaviour. Microstructural characterization has revealed that there are a number of defects in the cell structure which may contribute to the reduction in mechanical properties. These include: cell wall curvature, cell wall corrugations, density variations and non-equiaxed cell shape. Finite element analysis of a closed-cell tetrakaidecahedral unit cell with idealized curved or corrugated cell walls indicates that these two types of defects can reduce the Young's modulus and compressive strength by up to 70%. In this paper we report the results of measurements of the curvature of the cell walls and of the amplitude and frequency of corrugations in the cell walls and use simple bounds to estimate the reduction in modulus that they are responsible for.

scholarly journals Workflow to build a continuous static elastic moduli profile from the drilling data using artificial intelligence techniques

2021 ◽  
Author(s):  
Osama Siddig ◽  
Salaheldin Elkatatny
Keyword(s):  
Young’S Modulus ◽  
Elastic Moduli ◽  
Young's Modulus ◽  
Correlation Coefficients ◽  
Wellbore Stability ◽  
Machine Learning Techniques ◽  
Support Vector ◽  
Ann Model ◽  
Weight On Bit ◽  
Data Points

AbstractRock mechanical properties play a crucial role in fracturing design, wellbore stability and in situ stresses estimation. Conventionally, there are two ways to estimate Young’s modulus, either by conducting compressional tests on core plug samples or by calculating it from well log parameters. The first method is costly, time-consuming and does not provide a continuous profile. In contrast, the second method provides a continuous profile, however, it requires the availability of acoustic velocities and usually gives estimations that differ from the experimental ones. In this paper, a different approach is proposed based on the drilling operational data such as weight on bit and penetration rate. To investigate this approach, two machine learning techniques were used, artificial neural network (ANN) and support vector machine (SVM). A total of 2288 data points were employed to develop the model, while another 1667 hidden data points were used later to validate the built models. These data cover different types of formations carbonate, sandstone and shale. The two methods used yielded a good match between the measured and predicted Young’s modulus with correlation coefficients above 0.90, and average absolute percentage errors were less than 15%. For instance, the correlation coefficients for ANN ranged between 0.92 and 0.97 for the training and testing data, respectively. A new empirical correlation was developed based on the optimized ANN model that can be used with different datasets. According to these results, the estimation of elastic moduli from drilling parameters is promising and this approach could be investigated for other rock mechanical parameters.

scholarly journals Organizing Cells Within Non-Periodic Microarchitectured Materials That Achieve Graded Thermal Expansions

2015 ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Lucas A. Shaw ◽  
Todd H. Weisgraber ◽  
George R. Farquar ◽  
Christopher D. Harvey ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Thermal Expansion ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Element Analysis ◽  
Thermal Expansion Coefficients ◽  
Large Lattice ◽  
Unit Cells ◽  
Expansion Coefficients ◽  
Bulk Behavior

The aim of this paper is to introduce an approach for optimally organizing a variety of different unit cell designs within a large lattice such that the bulk behavior of the lattice exhibits a desired Young’s modulus with a graded change in thermal expansion over its geometry. This lattice, called a graded microarchitectured material, can be sandwiched between two other materials with different thermal expansion coefficients to accommodate their different expansions or contractions caused by changing temperature while achieving a desired uniform stiffness. First, this paper provides the theory necessary to calculate the thermal expansion and Young’s modulus of large multi-material lattices that consist of periodic (i.e., repeating) unit cells of the same design. Then it introduces the theory for calculating the graded thermal expansions of a large multimaterial lattice that consists of non-periodic unit cells of different designs. An approach is then provided for optimally designing and organizing different unit cells within a lattice such that both of its ends achieve the same thermal expansion as the two materials between which the lattice is sandwiched. A MATLAB tool is used to generate images of the undeformed and deformed lattices to verify their behavior and various examples are provided as case studies. The theory provided is also verified and validated using finite element analysis and experimentation.

The Site Tilt and Lander Transfer Function from the Short-Period Seismometer of InSight on Mars

2021 ◽  
Author(s):  
Alexander E. Stott ◽  
Constantinos Charalambous ◽  
Tristram J. Warren ◽  
William T. Pike ◽  
Robert Myhill ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Dust Devils ◽  
Total Change ◽  
Noise Sources ◽  
Element Analysis ◽  
Near Surface ◽  
Seismic Experiment ◽  
Short Period ◽  
Sensitivity Changes

ABSTRACT The National Aeronautics and Space Administration InSight mission has deployed the seismic experiment, SEIS, on the surface of Mars, and has recorded a variety of signals including marsquakes and dust devils. This work presents results on the tilt and local noise sources, which provide context to aid interpretation of the observed signals and allow an examination of the near-surface properties. Our analysis uses data recorded by the short-period sensors on the deck, throughout deployment and in the final configuration. We use thermal decorrelation to provide an estimate of the sol-to-sol tilt. This tilt is examined across deployment and over a Martian year. After each modification to the site, the tilt is seen to stabilize over 3–20 sols depending on the action, and the total change in tilt is <0.035°. Long-term tilt over a Martian year is limited to <0.007°. We also investigate the attenuation of lander-induced vibrations between the lander and SEIS. Robotic arm motions provide a known lander source in the 5–9 Hz bandwidth, yielding an amplitude attenuation of lander signals between 100 and 1000 times. The attenuation of wind sensitivity from the deck to ground presents a similar value in the 1.5–9 Hz range, thus favoring a noise dominated by lander vibrations induced by the wind. Wind sensitivities outside this bandwidth exhibit different sensitivity changes, indicating a change in the coupling. The results are interpreted through a finite-element analysis of the regolith with a depth-dependent Young’s modulus. We argue that discrepancies between this model and the observations are due to local compaction beneath the lander legs and/or anelasticity. An estimate for the effective Young’s modulus is obtained as 62–81 MPa, corroborating previous estimates for the top layer duricrust.

scholarly journals Finite Element Analysis of the Nanomechanics of Hard Coatings on a Soft Polymer Substrate by a Spherical Indenter

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Chunlai Tian ◽  
Pengfei Duan
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Viscoelastic Model ◽  
Coating System ◽  
Element Analysis ◽  
Soft Polymer ◽  
Indentation Response

Composite has been widely used in various fields due to its advanced performance. To reveal the relation between the mechanical properties of the composite and that of each individual component, finite element analysis (FEA) has usually been adopted. In this study, in order to predict the mechanical properties of hard coating on a soft polymer, the response of this coating system during nanoindentation was modelled. Various models, such as a viscoelastic model and fitting model, were adopted to analyse the indentation response of this coating system. By varying the substrate properties (i.e., Young’s modulus, viscoelasticity, and Poisson’s ratio), Young’s modulus, energy loss, and the viscoelastic model of the coating system were analysed, and how the mechanical properties of the substrate will affect the indentation response of the coating system was discussed.

Fabrication and Testing of Planar Stent Mesh Designs Using Carbon-Infiltrated Carbon Nanotubes

2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Kristopher Jones ◽  
Brian D. Jensen ◽  
Anton Bowden
Keyword(s):  
Carbon Nanotubes ◽  
Young’S Modulus ◽  
Fracture Strain ◽  
Young's Modulus ◽  
Chemical Vapor ◽  
Pyrolytic Carbon ◽  
Compression Tests ◽  
Element Analysis ◽  
Percent Elongation ◽  
Fea Model

This paper explores and demonstrates the potential of using pyrolytic carbon as a material for coronary stents. Stents are commonly fabricated from metal, which has worse biocompatibilty than many polymers and ceramics. Pyrolytic carbon, a ceramic, is currently used in medical implant devices due to its preferable biocompatibility properties. Micropatterned pyrolytic carbon implants can be created by growing carbon nanotubes (CNTs), and then filling the space between with amorphous carbon via chemical vapor deposition (CVD). We prepared multiple samples of two different stent-like flexible mesh designs and smaller cubic structures out of carbon-infiltrated carbon nanotubes (CI-CNT). Tension loads were applied to expand the mesh samples and we recorded the forces at brittle failure. The cubic structures were used for separate compression tests. These data were then used in conjunction with a nonlinear finite element analysis (FEA) model of the stent geometry to determine Young's modulus and maximum fracture strain in tension and compression for each sample. Additionally, images were recorded of the mesh samples before, during, and at failure. These images were used to measure an overall percent elongation for each sample. The highest fracture strain observed was 1.4% and Young's modulus values confirmed that the material was similar to that used in previous carbon-infiltrated carbon nanotube work. The average percent elongation was 86% with a maximum of 145%. This exceeds a typical target of 66%. The material properties found from compression testing show less stiffness than the mesh samples; however, specimen evaluation reveals poorly infiltrated samples.

Flatwise Young’s modulus and flatwise shear modulus of plywood measured by flexural vibration test

Holzforschung ◽  
2013 ◽  
Vol 67 (6) ◽  
pp. 683-690 ◽  
Author(s):  
Hiroshi Yoshihara
Keyword(s):  
Finite Element Analysis ◽  
Shear Modulus ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Flexural Vibration ◽  
Vibration Test ◽  
Specimen Length ◽  
Element Analysis ◽  
Flexural Vibration Test ◽  
Vibration Tests

Abstract The flatwise Young’s modulus and the flatwise shear modulus of 3-, 5-, and 7-ply plywoods made of Lauan (Shorea sp.) veneers have been determined by conducting flexural vibration tests with various specimen lengths and by finite element analysis. The results indicate that the flatwise Young’s modulus decreases with decreasing specimen length, whereas the opposite is true for the flatwise shear modulus.

scholarly journals Load transfer of nanocomposite film on aluminum substrate

2018 ◽  
Vol 16 (1_suppl) ◽  
pp. 10-16
Author(s):  
Shiuh-Chuan Her ◽  
Pao-Chu Chien
Keyword(s):  
Young’S Modulus ◽  
Nanocomposite Film ◽  
Load Transfer ◽  
Young's Modulus ◽  
Tensile Load ◽  
Beam Theory ◽  
Aluminum Substrate ◽  
Nanocomposite Films ◽  
Euler Beam ◽  
Load Carrying

Introduction: Nanocomposite films have attracted much attention in recent years. Depending on the composition of the film and fabrication method, a large range of applications has been employed for nanocomposite films. Method: In this study, nanocomposite films reinforced with multi-walled carbon nanotubes (MWCNTs) were deposited on the aluminum substrate through hot press processing. A shear lag model and Euler beam theory were employed to evaluate the stress distribution and load carrying capability of the nanocomposite film subjected to tensile load and bending moment. Results: The influence of MWCNT on the Young’s modulus and load carrying capability of the nanocomposite film was investigated through a parametric study. The theoretical predictions were verified by comparison with experimental tests. A close agreement with difference less than 6% was achieved between the theoretical prediction and experimental measurements. Conclusions: The Young’s modulus and load transfer of the nanocomposite film reinforced with MWCNTs increases with the increase of the MWCNT loading. Compared to the neat epoxy film, nanocomposite film with 1 wt % of MWCNT exhibits an increase of 20% in both the Young’s modulus and load carrying capability.

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