scholarly journals Hydromechanical modeling of granular soils considering internal erosion

2020 ◽  
Vol 57 (2) ◽  
pp. 157-172 ◽  
Author(s):  
Jie Yang ◽  
Zhen-Yu Yin ◽  
Farid Laouafa ◽  
Pierre-Yves Hicher
Keyword(s):  
Experimental Data ◽  
Mechanical Behavior ◽  
Fine Particles ◽  
Numerical Approach ◽  
Internal Erosion ◽  
Erosion Process ◽  
Incremental Model ◽  
Strain Relationship ◽  
Practical Model ◽  
Relationship Of

This paper attempts to formulate a coupled practical model in the framework of continuum mechanics to evaluate the phenomenon of internal erosion and its consequences on the mechanical behavior of soils. For this purpose, a four-constituent numerical approach has been developed to describe the internal erosion process. The detachment and transport of the fine particles have been described by a mass exchange formulation between the solid and fluid phases. The stress–strain relationship of the soil is represented by a nonlinear incremental model. Based on experimental data, this constitutive model has been enhanced by the introduction of a fines content–dependent critical state, which allows accounting for the influence of fines on soil deformation and strength. The applicability of the practical approach to capture the main features of the internal erosion process and its impact on the mechanical behavior of the eroded soil have been validated by comparing numerical and experimental results of internal erosion tests on Hong Kong completely decomposed granite (HK-CDG) mixtures, which demonstrated that the practical model was able to reproduce, with reasonable success, the experimental data. Furthermore, the influence of the stress state, the initial soil density, and the initial fraction of fines have been analyzed through numerical simulations using the proposed model.

Finite Element Simulation of Bolt-Up Process of Pipe Flange Connections With Spiral Wound Gasket

2003 ◽  
Vol 125 (4) ◽  
pp. 371-378 ◽  
Author(s):  
Toshimichi Fukuoka ◽  
Tomohiro Takaki
Keyword(s):  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Numerical Approach ◽  
Exponential Equation ◽  
Flange Connection ◽  
Element Simulation ◽  
Highly Nonlinear ◽  
Strain Relationship ◽  
Relationship Of ◽  
Spiral Wound

It is well known that a large amount of scatter in bolt preloads is observed when bolting up a pipe flange connection, especially in the case of using a spiral wound gasket. In this study, a numerical approach is proposed, which can simulate the bolt-up process of a pipe flange connection with a spiral wound gasket inserted. The numerical approach is designed so as to predict the scatter in bolt preloads and achieve uniform bolt preloads at the completion of pipe flange assembly. To attain the foregoing purposes, the stress-strain relationship of a spiral wound gasket, which shows highly nonlinear behavior, is identified with a sixth-degree polynomial during loading and with an exponential equation during unloading and reloading. Numerical analyses are conducted by three-dimensional FEM, in which a gasket is modeled as groups of nonlinear one-dimensional elements.

Mathematical and mechanical modeling of stress-strain relationship of pericardium

1975 ◽  
Vol 229 (4) ◽  
pp. 896-900 ◽  
Author(s):  
SW Rabkin ◽  
PH Hsu
Keyword(s):  
Experimental Data ◽  
Mechanical Model ◽  
Soft Tissues ◽  
Mechanical Modeling ◽  
Stress Strain ◽  
Mathematical Expressions ◽  
Strain Relationship ◽  
Relationship Of

Several mathematical expressions (models) were compared for use in describing the stress-strain (sigma - epsilon) relationship of pericardium. The expression sigma = alpha[ebeta epsilon - 1] was preferred because of its simpler form, theoretical consistency, and "good fit" of experimental data. A method was developed for estimating the precisions of the estimates of the parameters alpha and beta. This approach can have general usefulness in assessing the significance of a change in stress-strain relationship of various soft tissues following different interventions. A mechanical model was formulated for the pericardium which consisted of springs representing the collagen and elastin fibers connected in parallel. It could be simulated by the above equation and could describe the behavior of the pericardium.

A COUPLED EXPERIMENTAL AND NUMERICAL APPROACH TO CHARACTERIZE THE ANISOTROPIC MECHANICAL BEHAVIOR OF AORTIC TISSUES

2020 ◽  
Vol 20 (05) ◽  
pp. 2050027
Author(s):  
VERA GRAMIGNA ◽  
GIONATA FRAGOMENI ◽  
CHIARA GIULIA FONTANELLA ◽  
CESARE STEFANINI ◽  
EMANUELE LUIGI CARNIEL
Keyword(s):  
Experimental Data ◽  
Mechanical Behavior ◽  
Computational Models ◽  
Tensile Tests ◽  
Numerical Approach ◽  
Mechanical Tests ◽  
Mechanical Responses ◽  
Biomechanical Behavior ◽  
Axial Tensile ◽  
Constitutive Parameters

Nowadays, the investigation of aortic wall biomechanics is a fundamental tool in clinical research and vascular prosthesis design. This study aims at analyzing the biomechanical behavior of aortic tissues using a coupled experimental and computational approach. Considering the typical fiber-reinforced configuration of aortic tissues, uni-axial tensile tests along six different loading directions were performed on specimens from pig aorta. Starting from the obtained experimental data, a suitable constitutive framework was defined and a methodology for the identification of the constitutive parameters was developed using the inverse analysis of mechanical tests. Transversal stretch versus loading stretch and nominal stress versus loading stretch curves were evaluated, showing the anisotropic and nonlinear mechanical behavior determined by tissue conformation with fibers distributed along preferential directions. In detail, experimental data showed different mechanical responses between longitudinal and circumferential directions, with a greater tissue stiffness along the longitudinal one. The reliability of the developed constitutive framework was evaluated by the comparison between experimental data and model results. The mentioned analysis can be considered as a useful tool for the development of reliable computational models, which allow a better understanding of the pathophysiology of cardiovascular diseases and can be applied for a proper planning of surgical procedures.

Two Network Model for Vulcanizates Crosslinked under Strain

1967 ◽  
Vol 40 (4) ◽  
pp. 1060-1070
Author(s):  
H. Steve Yanai
Keyword(s):  
Experimental Data ◽  
Network Model ◽  
Present Theory ◽  
Chain Model ◽  
Premature Failure ◽  
Strain Relationship ◽  
Non Gaussian ◽  
Relationship Of ◽  
The Relationship ◽  
Level 2

Abstract The two network model of Berry, Scanlan, and Watson has been generalized by utilizing the simplified non-Gaussian, three-chain model of Treloar. The generalized two network model provides : (1) the relationship between effective stretch and applied stretch with a given precrosslink level, (2) the stress strain relationship of stretched, crosslinked elastomer, and (3) the relationship between anisotropic swelling behavior and the stretch-crosslinking conditions. Experimental results are in fair agreement with theory. However, due mainly to premature failure of specimens during the tensile test, the results are not quite enough to test the present theory adequately. Therefore additional experimental data are desirable, preferably from specimens with a wider range of the variables.

scholarly journals COMPRESSION INSTABILITIES OF TISSUES WITH LOCALIZED STRAIN SOFTENING

2011 ◽  
Vol 03 (01) ◽  
pp. 69-83 ◽  
Author(s):  
MICHEL DESTRADE ◽  
JOSE MERODIO
Keyword(s):  
Energy Density ◽  
Mechanical Behavior ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Soft Tissues ◽  
Strain Softening ◽  
Softening Effect ◽  
Bulk Surface ◽  
Strain Relationship ◽  
Relationship Of

The stress–strain relationship of biological soft tissues affected by Marfan's syndrome is believed to be nonconvex. More specifically, Haughton and Merodio recently proposed a strain energy density leading to localized strain-softening, in order to model the unusual mechanical behavior of these isotropic, incompressible tissues. Here we investigate how this choice of strain energy affects the results of some instabilities studies, such as those concerned with the compression of infinite and semi-infinite solids, slabs, and cylinders, or with the bending of blocks, and draw comparisons with known results established previously for the case of a classical neo-Hookean solid. We find that the localized strain-softening effect leads to early instability only when instability occurs at severe compression ratios for neo-Hookean solids, as is the case for bulk, surface, and bending instabilities.

Semi-inverse method for predicting stress–strain relationship from cone indentations

2003 ◽  
Vol 18 (9) ◽  
pp. 2068-2078 ◽  
Author(s):  
A. DiCarlo ◽  
H. T. Y. Yang ◽  
S. Chandrasekar
Keyword(s):  
A Priori ◽  
Model Material ◽  
Material Behavior ◽  
The Finite Element Method ◽  
Stress Strain ◽  
Indentation Tests ◽  
Strain Relationship ◽  
Initial Force ◽  
Relationship Of ◽  
Force Displacement

A method for determining the stress–strain relationship of a material from hardness values H obtained from cone indentation tests with various apical angles is presented. The materials studied were assumed to exhibit power-law hardening. As a result, the properties of importance are the Young's modulus E, yield strength Y, and the work-hardening exponent n. Previous work [W.C. Oliver and G.M. Pharr, J. Mater. Res. 7, 1564 (1992)] showed that E can be determined from initial force–displacement data collected while unloading the indenter from the material. Consequently, the properties that need to be determined are Y and n. Dimensional analysis was used to generalize H/E so that it was a function of Y/E and n [Y-T. Cheng and C-M. Cheng, J. Appl. Phys. 84, 1284 (1999); Philos. Mag. Lett. 77, 39 (1998)]. A parametric study of Y/E and n was conducted using the finite element method to model material behavior. Regression analysis was used to correlate the H/E findings from the simulations to Y/E and n. With the a priori knowledge of E, this correlation was used to estimate Y and n.

Study on Stress-Strain Relationship of Loess

2004 ◽  
Vol 274-276 ◽  
pp. 241-246 ◽  
Author(s):  
Bo Han ◽  
Hong Jian Liao ◽  
Wuchuan Pu ◽  
Zheng Hua Xiao
Keyword(s):  
Stress Strain ◽  
Strain Relationship ◽  
Relationship Of
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