scholarly journals Displacement Analyses for a Natural Slope Considering Post-Peak Strength of Soils

GeoHazards ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 41-62
Author(s):  
Chien-Li Lo ◽  
Ching-Chuan Huang
Keyword(s):  
Peak Stress ◽  
Groundwater Table ◽  
Peak Strength ◽  
Failure Envelope ◽  
Displacement Method ◽  
Natural Slope ◽  
Material Parameters ◽  
Novel Method ◽  
Slope Displacement ◽  
Force Equilibrium

A natural slope undergoing recurrent movements caused by rainfall-induced groundwater table rises is studied using a novel method. The strength and displacement parameters are back-calculated using a force-equilibrium-based finite displacement method (FFDM) based on the first event of slope movement recorded in the monitoring period. Slope displacements in response to subsequent rainfall-induced groundwater table rises are predicted using FFDM based on the back-calculated material parameters. Important factors that may influence the accuracy of slope displacement predictions, namely, the curvature of the Mohr-Coulomb (M-C) failure envelope and post-peak strength softening, are investigated. It is found that the accuracy of slope displacement predictions can be improved by taking into account post-peak stress-displacement relationship in the analysis. The accuracy of slope displacement predictions is not influenced by the curvature of the M-C failure envelope in the displacement analysis.

scholarly journals Experimental and Numerical Investigation of Failure Characteristics and Mechanism of Granites with Different Joint Angles

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhenhua Wang ◽  
Jun Fang ◽  
Gang Wang ◽  
Yifan Jiang ◽  
Dongwei Li
Keyword(s):  
Elastic Modulus ◽  
Uniaxial Compression ◽  
Elastic Strain Energy ◽  
Peak Stress ◽  
Peak Strength ◽  
Particle Flow Code ◽  
Dissipated Energy ◽  
Shear Cracks ◽  
Compression Tests ◽  
Dip Angle

The uniaxial compression tests were conducted on granite samples with different joint dip angles to more favorably explore the influences of the nonconsecutive joint on mechanical properties and deformation characteristics of the rock mass. The stress-strain curves, deformation and strength characteristics, and energy evolution process of the samples were analyzed. Numerical simulation using particle flow code (PFC) is employed to study the crack propagation process. The mode of jointed and fractured rock was investigated. The research results showed a significant reduction in both the peak strength and elastic modulus of jointed samples compared with intact ones: the peak strength and elastic modulus drop to the minimum at the joint dip angle of about 45°, especially for the peak strength, which takes up about 55% of the intact samples. The fractured samples’ total energy, elastic strain energy, and dissipated energy during the uniaxial compression drop significantly relative to intact samples. The proportion of the fracture modes varies with different joint dip angles, in which the ratio of shear cracks grows at first and then declines, with the highest balance at the dip angle of 45°. The damage stress’s sensitivity to the dip angle change is greater than that of the peak stress, with reduction amplitude more extensive than the latter.

Dynamic Beam Modification Using Dimples

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
W. N. Cheng ◽  
C. C. Cheng ◽  
G. H. Koopmann
Keyword(s):  
Natural Frequencies ◽  
Design Method ◽  
Frequency Equation ◽  
Search Method ◽  
The Other ◽  
Impedance Method ◽  
Dimple Size ◽  
Straight Beam ◽  
Novel Method ◽  
Force Equilibrium

In this paper, a design method to modify the vibration characteristics of a beam by creating cylindrical dimples on its surface is investigated. In particular, the vibration response of a beam with several dimples is formulated using the impedance method. The dimpled beam is divided into two kinds of structural segments: one, a curved beam that is modeled as the dimple and the other, a straight beam. The frequency equation is derived by assembling the impedance of each structure segment based on conditions of force equilibrium and velocity compatibility. Then a novel method for shifting the natural frequencies of a beam to preassigned values by creating cylindrical dimples on this structure is introduced. The dimple size and its location on the structure can be determined analytically, so the time consuming process using the traditional optimal search method is thereby avoided. Several examples using this technique are demonstrated.

scholarly journals An inverse method for mechanical characterization of heterogeneous diseased arteries using intravascular imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bharath Narayanan ◽  
Max L. Olender ◽  
David Marlevi ◽  
Elazer R. Edelman ◽  
Farhad R. Nezami
Keyword(s):  
In Silico ◽  
Mechanical Characterization ◽  
Imaging Data ◽  
New Approach ◽  
Parameter Recovery ◽  
Material Parameters ◽  
Linear Elastic ◽  
Novel Method

AbstractThe increasing prevalence of finite element (FE) simulations in the study of atherosclerosis has spawned numerous inverse FE methods for the mechanical characterization of diseased tissue in vivo. Current approaches are however limited to either homogenized or simplified material representations. This paper presents a novel method to account for tissue heterogeneity and material nonlinearity in the recovery of constitutive behavior using imaging data acquired at differing intravascular pressures by incorporating interfaces between various intra-plaque tissue types into the objective function definition. Method verification was performed in silico by recovering assigned material parameters from a pair of vessel geometries: one derived from coronary optical coherence tomography (OCT); one generated from in silico-based simulation. In repeated tests, the method consistently recovered 4 linear elastic (0.1 ± 0.1% error) and 8 nonlinear hyperelastic (3.3 ± 3.0% error) material parameters. Method robustness was also highlighted in noise sensitivity analysis, where linear elastic parameters were recovered with average errors of 1.3 ± 1.6% and 8.3 ± 10.5%, at 5% and 20% noise, respectively. Reproducibility was substantiated through the recovery of 9 material parameters in two more models, with mean errors of 3.0 ± 4.7%. The results highlight the potential of this new approach, enabling high-fidelity material parameter recovery for use in complex cardiovascular computational studies.

Coefficients of Transverse Contraction of the Wood Cell Constituents and their Effect on the Cell Behavior

2016 ◽  
Vol 714 ◽  
pp. 20-24 ◽  
Author(s):  
Vera Hlavata ◽  
Pavel Kuklik ◽  
Martin Hataj
Keyword(s):  
Stress State ◽  
Transversely Isotropic ◽  
Cell Behavior ◽  
Cylinder Surface ◽  
Main Task ◽  
Displacement Method ◽  
Material Parameters ◽  
Calculation Results ◽  
Hollow Cylinders ◽  
State Transmission

Wood cells are composed of cellulose, hemicellulose, and lignin. Geometrically we can idealize them as a set of hollow cylinders touching each other on the cylinder surface. The continuous displacements and stress state transmission are assumed on the cylinder surfaces. The article investigates stress development which is influenced by the wood cell axial elongation. Material properties of individual constituents are generally described by nine parameters characterizing orthotropic elastic material. Transversely isotropic constitutive model of was chosen for simplification. The analytical solution of the stress state was driven by the ideas of displacement method. Material parameters have been estimated according to available literature. The main task of our investigation was focused on the effect of transversal contraction. The actual calculation results are surprising and lead to reflection. These considerations and conclusions are summarized at the end of the paper.

Experimental technique for high-frequency conductivity measurement

2019 ◽  
Vol 38 (5) ◽  
pp. 1711-1722
Author(s):  
Károly Marák ◽  
Sándor Bilicz ◽  
József Pávó
Keyword(s):  
Resonance Frequency ◽  
High Frequency ◽  
Doppler Effect ◽  
Main Idea ◽  
Conductivity Measurement ◽  
Content Type ◽  
Material Parameters ◽  
Electromagnetic Resonance ◽  
Novel Method ◽  
Conductive Properties

Purpose The purpose of this study is to introduce a novel method for the measurement of electromagnetic material parameters. Design/methodology/approach The main idea behind the approach is the fact that for slabs with elongated shapes, the intensity of the backscattered field and the electromagnetic resonance frequency corresponding to the length of the sample are dependent on the conductivity of the sample’s material. Findings It is shown that for a known scattered field and resonance frequency, it is possible to formulate an inverse problem as to the calculation of the conductivity of the sample’s material at the considered frequencies. To investigate the applicability of the method, demonstrative experiments are performed during which the micro-Doppler effect is used to increase the measurement accuracy. The idea is extended to the case of anisotropic samples, with slight modifications proposed to the experimental setup in the case of significant anisotropy in the investigated material. Practical implications The measurement method may prove useful for the investigation of the high-frequency conductive properties of certain materials of interest. Originality/value To the best of the authors’ knowledge, this is the first time the use of the micro-Doppler effect is proposed for the purpose of the measurement of material parameters.

A Novel Method for Designing Electromagnetic Shrinking Device With Homogeneous Material Parameters

2013 ◽  
Vol 49 (10) ◽  
pp. 5280-5286 ◽  
Author(s):  
Tinghua Li ◽  
Ming Huang ◽  
Jingjing Yang ◽  
Wenjin Zhu ◽  
Jia Zeng
Keyword(s):  
Homogeneous Material ◽  
Material Parameters ◽  
Novel Method

Surface Induction Hardening Models Based on a Novel Computational Method of Artificial Change of Material Parameters

2010 ◽  
Vol 670 ◽  
pp. 517-525 ◽  
Author(s):  
Ladislav Musil
Keyword(s):  
Surface Layer ◽  
Computer Model ◽  
Eddy Currents ◽  
Induction Hardening ◽  
Computational Method ◽  
Material Parameters ◽  
Hardening Models ◽  
Novel Method ◽  
Surface Induction

The paper deals with a novel method suitable for modelling of surface induction hardening and other tasks, where the problem of discretisation of very thin eddy-currents surface layer is present. The method is based on artificial change of material parameters in the computer model. A methodology is suggested and limitations of its application are thoroughly tested. Odds and merits over other possible methods are also discussed.

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