Large deformation dynamic analysis of unsaturated soils

2014 ◽  
pp. 755-760 ◽  
Author(s):  
B Khan ◽  
G Esgandani ◽  
N Khalili
Keyword(s):  
Dynamic Analysis ◽  
Large Deformation ◽  
Unsaturated Soils

Model for predicting the variation of shear stress in unsaturated soils during strain-softening

2020 ◽  
Author(s):  
Xiuhan Yang ◽  
Sai Vanapalli
Keyword(s):  
Shear Stress ◽  
Large Deformation ◽  
Unsaturated Soils ◽  
Strain Softening ◽  
Strain Curve ◽  
Published Data ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Strain Relationship ◽  
State Stress

Several of the geotechnical structures constructed with unsaturated soils undergo a large deformation prior to reaching failure conditions (e.g. progressive failure of a soil slope). During this process, the shear stress in soils typically increases initially and then reduces with an increase in the shear strain. The prediction of the stress-strain relationship is critical for reasonable interpretation of the mechanical behavior of those geo-structures that undergo large deformation. This paper introduces a model based on the disturbed state concept (DSC) to predict the variation of shear stress in unsaturated soils during strain-softening process under consolidated drained triaxial compression condition. In this model, the apparent stress-strain relationship is formulated as a weighted average of a hyperbolic hardening response extending the pre-peak state stress-strain curve and a linear response extending the critical state stress-strain curve with an assumed disturbance function as the weight. The prediction procedure is described in detail and the proposed model is validated using several sets of published data on unsaturated soils varying from coarse- to fine-grained soils. Finally, a comprehensive error analysis is undertaken based on an index of agreement approach.

Dynamic Analysis of Soft Tissue considering Characteristic of Viscoelastic and Large Deformation

2002 ◽  
Vol 2002.40 (0) ◽  
pp. 33-34
Author(s):  
Izumi UENO ◽  
Takashi SAITO ◽  
Masaaki OKA ◽  
Atushi SAKUMA ◽  
Kimihiko NAKANO
Keyword(s):  
Soft Tissue ◽  
Dynamic Analysis ◽  
Large Deformation

Dynamic Analysis of Unsaturated Soils Subjected to Large Deformations

2016 ◽  
Vol 846 ◽  
pp. 354-359 ◽  
Author(s):  
Javad Ghorbani ◽  
Majidreza Nazem ◽  
John Phillip Carter
Keyword(s):  
Constitutive Model ◽  
Dynamic Analysis ◽  
Unsaturated Soils ◽  
Experimental Studies ◽  
Mixture Theory ◽  
Saturated Soils ◽  
Deformation Analysis ◽  
Mechanical Coupling ◽  
Partially Saturated ◽  
Partially Saturated Soils

This paper deals with the large deformation analysis of partially saturated soils subjected to dynamic loading. The so-called ‘mixture’ theory is employed to consider the hydro-mechanical coupling involved in this kind of problem. The finite element method is used to discretise the problem domain and the generalized-α algorithm is employed to integrate the governing equations over time. Some of the most challenging aspects of dynamic analysis of partially saturated soils will be discussed. One of the key challenges is selecting a consistent constitutive model within the theory of mixtures that can incorporate the pore suction forces into the description of stress. The necessity of such incorporation has frequently been reported in experimental studies of unsaturated soils. To tackle this problem, a unique strategy for integrating the constitutive model for unsaturated soils is adopted. Moreover, an absorbing boundary condition, which prevents wave reflection from rigid boundaries, is introduced and implemented into the numerical algorithm. Finally, a solution for the problem of dynamic compaction of soil in a partially saturated condition is presented.

Nonlinear Dynamic Analysis of Cantilever Beam Using POD Based Reduced Order Model

2015 ◽  
Vol 786 ◽  
pp. 398-403 ◽  
Author(s):  
Kulkarni Atul Shankar ◽  
Manoj Pandey
Keyword(s):  
Dynamic Analysis ◽  
Large Deformation ◽  
Cantilever Beam ◽  
Nonlinear Dynamic ◽  
Degrees Of Freedom ◽  
Numerical Technique ◽  
Nonlinear Dynamic Analysis ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order

In this paper, a reduced order model is obtained for nonlinear dynamic analysis of a cantilever beam. Nonlinearity in the system is basically due to large deformation. A reduced order model is an efficient method to formulate low order dynamical model which can be obtained from data obtained from numerical technique such as finite element method (FEM). Nonlinear dynamical models are complex with large number of degrees of freedom and hence, are computationally intensive. With formulation of reduced order models (i.e. Macromodels) number of degrees of freedom are reduced to fewer degrees of freedom by using projection based method like Galerkin’s projection, so as to make system computationally faster and cost effective. These macromodels are obtained by extracting global basis functions from fully meshed model runs. Macromodels are generated using technique called proper orthogonal decomposition (POD) which gives good linear fit for the nonlinear systems. Using POD based macromodel, response of system can be computed using fewer modes instead of considering all modes of system. Macromodel is generated to obtain the response of cantilever beam with large deformation and hence, simulation time is reduced by factor of 90 approximately with error of order of 10-4. Further, method of POD based reduced order model is aplied to beam with different loading conditions to check the robustness of the macromodel. POD based macromodel response gives good agreement with FEA model response for a cantilever beam.

Large Deformation Dynamic Analysis of a Cable System by a New Hamiltonian Finite Element Method

2021 ◽  
Author(s):  
Huaiping Ding ◽  
Xiaochun Yin ◽  
Qiao Wang ◽  
Zheng H. Zhu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Large Deformation ◽  
Large Strain ◽  
Finite Elasticity ◽  
Cable System ◽  
Pendulum System ◽  
Flexible Cable ◽  
Element Method

This paper develops a new Hamiltonian nodal position finite element method for dynamic analysis of spatial flexible cable systems with large deformation. The dynamic governing equation is derived from finite elasticity theory. Logarithmic strain is applied to construct large deformation Hamiltonian canonical equations. An efficient second-order symplectic difference algorithm is built to solve the canonical equations numerically. A large strain conical pendulum system is analyzed numerically by the proposed method, and the numerical results are compared with those retracted from the existing Hamiltonian methods and Livermore Software Technology Corporation: dynamics (LS-DYNA). The proposed method is further verified by two tethered dynamic experiments involving large displacement motion and large deformation. The comparisons and verifications demonstrate that the proposed method is of symplectic conservation, has high accuracy and has stability for calculating flexible cable system dynamics with large deformation.

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