Shear strength and yield surface of a partially saturated sandy silt under generalized stress states

2021 ◽  
Author(s):  
Rodrigo Carreira Weber ◽  
Enrique E. Romero Morales ◽  
Antonio Lloret
Keyword(s):  
Shear Strength ◽  
Yield Surface ◽  
Experimental Results ◽  
Model Parameters ◽  
Hollow Cylinder Apparatus ◽  
Clayey Silt ◽  
Lode Angle ◽  
Yield Surfaces ◽  
Stress States ◽  
Deviatoric Stresses

This paper studies the hydromechanical behavior of a slightly compacted mixture of sand and clayey silt (30%/70%) under a generalized stress state. The experimental study focused on analyzing the yielding response and shear strength behavior at different stress states (characterized by the intermediate principal stress parameter b, or Lode angle) and at different initial total suctions (as-compacted state). For the investigation, a hollow cylinder apparatus was used. The shear strength results allowed defining the variation of the critical state line with the Lode angle and the suction. Different models were proposed for isotropic and anisotropic yield surfaces, and their shape and rotation were calibrated with experimental results. The modeled yield surfaces fitted reasonably well the experimental results, considering their inclination and dependence on the suction, mean and deviatoric stresses and Lode angle. In addition, some relationships between the stresses and the model parameters were proposed to normalize the yield surface equation.

Holdup and holdup profiles in the reciprocating plate extractor VPE

1990 ◽  
Vol 55 (11) ◽  
pp. 2648-2661 ◽  
Author(s):  
Helena Sovová ◽  
Vladislav Bízek ◽  
Jaroslav Procházka
Keyword(s):  
Steady State ◽  
Experimental Results ◽  
Model Parameters ◽  
Dispersed Phase ◽  
Pulse Form ◽  
Sieve Plates

In this work measurements of mean holdup of dispersed phase, of axial holdup profiles and of flooding points in a reciprocating plate contactor with both the VPE-type plates and the sieve plates were carried out. The experimental results were compared with a monodisperse model of steady-state column hydrodynamics and the model parameters were evaluated. Important differences in the behaviour of the two plate types could be identified. Comparison was also made between two reciprocating drives of different pulse form.

scholarly journals Characterization of Moisture Diffusion in Cured Concrete Slabs at Early Ages

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Xiao Zhang ◽  
Hongduo Zhao
Keyword(s):  
Process Model ◽  
Model Simulation ◽  
Moisture Diffusion ◽  
Experimental Results ◽  
Concrete Slabs ◽  
Model Parameters ◽  
Early Age ◽  
Water Curing ◽  
Early Age Concrete

The objective of this paper is to investigate the characterization of moisture diffusion inside early-age concrete slabs subjected to curing. Time-dependent relative humidity (RH) distributions of three mixture proportions subjected to three different curing methods (i.e., air curing, water curing, and membrane-forming compounds curing) and sealed condition were measured for 28 days. A one-dimensional nonlinear moisture diffusion partial differential equation (PDE) based on Fick’s second law, which incorporates the effect of curing in the Dirichlet boundary condition using a concept of curing factor, is developed to simulate the diffusion process. Model parameters are calibrated by a genetic algorithm (GA). Experimental results show that the RH reducing rate inside concrete under air curing is greater than the rates under membrane-forming compound curing and water curing. It is shown that the effect of water-to-cement (w/c) ratio on self-desiccation is significant. Lower w/c ratio tends to result in larger RH reduction. RH reduction considering both effect of diffusion and self-desiccation in early-age concrete is not sensitive to w/c ratio, but to curing method. Comparison between model simulation and experimental results indicates that the improved model is able to reflect the effect of curing on moisture diffusion in early-age concrete slabs.

scholarly journals Stress Triaxiality and Lode Angle Parameter Characterization of Flat Metal Specimen with Inclined Notch

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1627
Author(s):  
Jian Peng ◽  
Peishuang Zhou ◽  
Ying Wang ◽  
Qiao Dai ◽  
David Knowles ◽  
...  
Keyword(s):  
Stress State ◽  
Notch Root ◽  
Stress Triaxiality ◽  
Image Correlation ◽  
Notch Angle ◽  
Strain Evolution ◽  
Metal Specimen ◽  
Lode Angle ◽  
Stress States ◽  
Angle Parameter

The stress state has an important effect on the deformation and failure of metals. While the stress states of the axisymmetric notched bars specimens are studied in the literature, the studies on the flat metal specimen with inclined notch are very limited and the stress state is not clearly characterized in them. In this paper, digital image correlation and finite element simulations are used to study the distribution of strain and stress state, that is stress triaxiality and Lode angle parameter. Flat specimen with inclined notch was tested to extract the full field strain evolution and calculate stress state parameters at three locations: specimen centre, notch root and failure starting point. It is found that compared with the centre point and the notch root, the failure initiation point can better characterize the influence of the notch angle on the strain evolution. Conversely, the centre point can more clearly characterize the effect of the notch angle on stress state, since the stress states at the failure point and the notch root change greatly during the plastic deformation. Then the calculated stress state parameters of the flat metal specimen with inclined notch at the centre point are used in Wierzbicki stress state diagram to establish a relationship between failure mode and stress state.

A finite-deformation constitutive model of particle-binder composites incorporating yield-surface-free plasticity

2021 ◽  
pp. 1-32
Author(s):  
Ankit Agarwal ◽  
Marcial Gonzalez
Keyword(s):  
Constitutive Model ◽  
Yield Surface ◽  
Finite Deformation ◽  
Large Strain ◽  
Elastic Response ◽  
Rate Equations ◽  
Internal Variables ◽  
Model Parameters ◽  
Stress Strain ◽  
Stress Softening

Abstract We present a constitutive model for particle-binder composites that accounts for finite-deformation kinematics, nonlinear elasto-plasticity without apparent yield, cyclic hysteresis, and progressive stress-softening before the attainment of stable cyclic response. The model is based on deformation mechanisms experimentally observed during quasi-static monotonic and cyclic compression of mock Plastic-Bonded Explosives (PBX) at large strain. An additive decomposition of strain energy into elastic and inelastic parts is assumed, where the elastic response is modeled using Ogden hyperelasticity while the inelastic response is described using yield-surface-free endochronic plasticity based on the concepts of internal variables and of evolution or rate equations. Stress-softening is modeled using two approaches; a discontinuous isotropic damage model to appropriately describe the softening in the overall loading-unloading response, and a material scale function to describe the progressive cyclic softening until cyclic stabilization. A nonlinear multivariate optimization procedure is developed to estimate the elasto-plastic model parameters from nominal stress-strain experimental compression data. Finally, a correlation between model parameters and the unique stress-strain response of mock PBX specimens with differing concentrations of aluminum is identified, thus establishing a relationship between model parameters and material composition.

Prediction of Stress-Strain Response Using Rotational Multiple Yield Surface Framework in Malaysian Residual Soil

2020 ◽  
Vol 843 ◽  
pp. 132-137
Author(s):  
Asmidar Alias ◽  
Mohd Jamaludin Md Noor ◽  
Abdul Samad Abdul Rahman
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Volume Change ◽  
Yield Surface ◽  
Axial Strain ◽  
The Body ◽  
Residual Soil ◽  
Strain Response ◽  
Stress Strain ◽  
Soil Volume

Soil settlement is normally quantified using conventional soil volume change models which are solely based on the effective stress and the role of shear strength is ignored due to the difficulties to incorporate in the framework. The Rotational Multiple Yield Surface Framework (RMYSF) is a soil volume change model developed from the standpoint of the interaction between the effective stress and shear strength. RMYSF incorporates the development of mobilised shear strength within the body of the soil whenever the soil is subjected to anisotropic compression. Currently the framework has been applied to predict the soil anisotropic stress-strain behaviour at any effective stress. This paper present the enhancement of this volume change framework using normalisation of axial strain with the understanding that the failure axial strain is not unique, but increases as the effective stress increases. This technique has essentially produced a better accuracy in the prediction of the stress-strain response for Malaysian residual soils. A series of drained tri-axial tests under various effective stresses has been conducted using specimens of 50mm diameter and 100mm height and from the stress-strain curves the inherent mobilised shear strength envelopes at various axial strains have been determined. These mobilised shear strength envelopes were then applied for the prediction of the soil stress-strain response. An excellent agreement between the predicted and the actual stress-strain curves has been achieved.

Effect of CU Foam and Ag-Coated Layer on the Microstructure and Mechanical Behavior of Nano-Ag Sintered Joint

2020 ◽  
Author(s):  
Yang Liu ◽  
Zhao Li ◽  
Min Zhou ◽  
Xianghua Zeng ◽  
Fenglian Sun
Keyword(s):  
Shear Strength ◽  
Mechanical Behavior ◽  
Bonding Strength ◽  
Experimental Results ◽  
Bonding Quality ◽  
Deformation Ratio ◽  
Coated Layer ◽  
Ag Paste ◽  
Sintered Ag ◽  
Cu Foam

Abstract Cu foam (Cu-F) and Ag-coated Cu-F were added into nano-Ag paste to obtain Cu-F@nano-Ag composite sintered joint. The microstructure, hardness, and shear behavior of the sintered joints were investigated. Experimental results indicated that the addition of Cu-F and Ag-coated Cu-F suppressed the generation and propagation of cracks at the interface of the sintered joint. As the thickness of the Cu-F increased from 0.1mm to 0.2mm, the deformation ratio of the Cu-F sheet raised from 12 % to 50 %. Thereby, the hardness and bonding strength of the sintered joint was improved due to the microstructural densification. The bonding quality between Cu-F and sintered Ag is enhanced by the Ag-coating treatment. Therefore, the Ag-coated composite joints show higher shear strength than the others.

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