Simulation of time-dependent movements in Syncrude tailings dyke foundation

1998 ◽  
Vol 35 (2) ◽  
pp. 284-298 ◽  
Author(s):  
AMP Wedage ◽  
N R Morgenstern ◽  
D H Chan
Keyword(s):  
Residual Strength ◽  
Time Dependent ◽  
Deformation Analysis ◽  
Foundation Soil ◽  
Clay Shale ◽  
Soil Plasticity ◽  
Rate Dependent ◽  
Rate Effects ◽  
Clearwater Formation ◽  
Using Data

Foundation movements at the Syncrude tailings dyke continued over several years in response to the construction of the dyke. Major movements have been observed in a relatively narrow layer of previously sheared clay-shale material of the Clearwater Formation. The residual strength of this highly plastic clay increases with the rate of shear. By reviewing the existing literature on the rate effects on residual strength and using data from new experiments on Clearwater Clay Shale, a general correlation between soil plasticity and rate effects is found. This rate dependence of the residual strength of Clearwater clay shale has been incorporated into a deformation analysis, which made it possible to compute time-dependent movements of the foundation soil to a satisfactory level. By using a rate-dependent plasticity model, a prediction of anticipated foundation velocities and how they decrease with time may be achieved.Key words: finite element, rate effects, residual strength, Syncrude tailings dyke, time-dependent movements.

A strain rate dependent constitutive model for clays at residual strength

1998 ◽  
Vol 35 (2) ◽  
pp. 364-373 ◽  
Author(s):  
AMP Wedage ◽  
N R Morgenstern ◽  
D H Chan
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Residual Strength ◽  
Plasticity Theory ◽  
Constitutive Relationship ◽  
Plastic Strain Rate ◽  
Flow Rule ◽  
Rate Dependent ◽  
Dependent Part ◽  
Rate Effects

Plasticity theory is extended to incorporate strain rate effects on the residual shear strength of clays. The clay is assumed to behave elastically before yielding and then in a perfectly plastic manner with no volume change during yielding. The Mohr-Coulomb failure criterion is used in the rate-dependent model in which the strain rate affects the mobilized effective friction angle of the material. During initial yielding and subsequent plastic deformation, the stress and strain states at a point will satisfy the rate-dependent yield function (loading function). When the effective plastic strain rate decreases to a threshold strain value, the loading surface moves, or collapses, to the static yield surface. A constant volume flow rule is used to calculate plastic deformation. The computed stress-strain relationship is formulated in two parts, namely a rate-independent part and a rate-dependent part. The rate-independent part is the same as that used in classical elastoplastic formulations, whereas the rate-dependent part is dependent on the current strain rate of the material. The use of the model is illustrated using a numerical example simulating a two-dimensional plane strain test.Key words: constitutive relationship, finite element, plasticity theory, pre-sheared clay, rate effects, residual strength.

Cohesive Layer Modeling of Time-Dependent Debond Growth in Aggressive Environments

2005 ◽  
Vol 128 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Samit Roy ◽  
Yong Wang ◽  
Soojae Park ◽  
Kenneth M. Liechti
Keyword(s):  
Time Dependent ◽  
Mixed Mode Fracture ◽  
Test Bed ◽  
Moisture Concentration ◽  
Simplified Approach ◽  
Rate Dependent ◽  
Nonlinear Viscoelastic ◽  
Convolution Integrals ◽  
Dependent Behavior ◽  
Moving Wedge

The objective of this paper is to model the synergistic bond-degradation mechanisms that may occur at the interface between a fiber-reinforced polymer (FRP) that is adhesively bonded to a substrate and subjected to elevated temperature and humidity. For this purpose, a two-dimensional cohesive-layer constitutive model with a prescribed traction-separation law is constructed from fundamental principles of continuum mechanics and thermodynamics, taking into account strain-dependent, non-Fickian hygrothermal effects as well as diffusion-induced degradation in the cohesive layer. In the interest of solution tractability, a simplified approach is employed where the rate-dependent behavior in the cohesive layer is implemented through the characterization of rate dependence of the maximum stresses and maximum strains in the cohesive layer, rather than through the use of convolution integrals in the free-energy definition. The remainder of the polymeric adhesive outside the cohesive layer is modeled as a nonlinear viscoelastic continuum with time-dependent constitutive behavior. The influence of temperature and moisture concentration on the work-of-separation and on crack growth is derived from first principles. The model is implemented in a test-bed finite element code. Results predicted by the computational model are benchmarked through comparison to experimental data from mixed-mode fracture experiments performed using a moving wedge test.

Numerical simulation of physiologically relevant pulsatile flow of blood with shear-rate-dependent viscosity in a stenosed blood vessel

2018 ◽  
Vol 11 (06) ◽  
pp. 1850082
Author(s):  
Subrata Mukhopadhyay ◽  
Mani Shankar Mandal ◽  
Swati Mukhopadhyay
Keyword(s):  
Numerical Simulation ◽  
Blood Flow ◽  
Blood Vessel ◽  
Pulsatile Flow ◽  
Time Dependent ◽  
Governing Equations ◽  
Rate Dependent ◽  
Realistic Situation ◽  
Newtonian Case ◽  
Dependent Viscosity

Pulsatile flow of blood in a blood vessel having time-dependent shape (diameter) is investigated numerically in order to understand some important physiological phenomena in arteries. A smooth axi-symmetric cosine shaped constriction is considered. To mimic the realistic situation as far as possible, viscosity of blood is taken to be non-uniform, a shear-thinning viscosity model is considered and a physiologically relevant pulsatile flow is introduced. Taking advantage of axi-symmetry in the proposed problem, the stream function–vorticity formulation is used to solve the governing equations for blood flow. Effect of different parameters associated with the problem on the flow pattern has been investigated and disparities from the Newtonian case are discussed in detail.

The Denholm landslide, Saskatchewan, Canada, an update

1987 ◽  
Vol 24 (1) ◽  
pp. 163-168 ◽  
Author(s):  
E. Karl Sauer ◽  
E. A. Christiansen
Keyword(s):  
Shear Strength ◽  
Key Words ◽  
Residual Strength ◽  
Average Rate ◽  
Clay Shale ◽  
Movement Rates ◽  
The North ◽  
Lower Block ◽  
Geological Age ◽  
Retrogressive Landslide

The lower block of the Denholm landslide has moved 370 m over alluvium deposited by the North Saskatchewan spillway and river during the last 11 500 years at an average rate of 32 mm/year. These values must be considered minimal because erosion of the toe of the landslide is required for the formation of retrogressive landslides. The shear strength for the bedrock clay (shale) of the Lea Park Formation was back calculated to be [Formula: see text] assuming zero cohesion. Key words: retrogressive landslide, clay shale, residual strength, movement rates, geological age, inclinometer.

Thermal wrinkling behavior of formable decorative film laminates

2016 ◽  
Vol 33 (3) ◽  
pp. 290-308 ◽  
Author(s):  
G Prasath Balamurugan ◽  
Rohan N Pukadyil ◽  
Mahdy M Malayery ◽  
Michael R Thompson ◽  
John Vlachopoulos ◽  
...  
Keyword(s):  
Heating Rate ◽  
Thermal Stresses ◽  
Metal Substrate ◽  
Rate Effect ◽  
Time Dependent ◽  
Threshold Temperature ◽  
Viscoelastic Response ◽  
Final Temperature ◽  
Rate Effects ◽  
Compliant Layer

This paper focuses on wrinkle development in decorative film laminates during heating operations with the goal to understand their driving factors and develop strategies to overcome such defects. The study looked at temperature and heating rate effects on the wrinkling behavior of a commercial black-out film laminated onto a metal substrate. The 135℃ threshold temperature identified for our film under which no wrinkles formed, related to the stiffness of its different construction layers. Heating rate was also noted by this study to be an important parameter in wrinkling; values between 1℃ and 350℃/min were tested. It was possible to exceed the threshold temperature stated above without wrinkling when the heating rate was sufficiently low (closer to 1℃/min, though less than 50℃/min was often sufficient depending on the final temperature). The heating rate effect is believed to be related to the time-dependent viscoelastic response of the compliant layer in relation to building thermal stresses.

TIME-DEPENDENT MECHANICAL BEHAVIOR OF CARBON BLACK FILLED ELASTOMERS

2011 ◽  
Vol 84 (3) ◽  
pp. 296-324 ◽  
Author(s):  
Aparajita Bhattacharya ◽  
Grigori A. Medvedev ◽  
James M. Caruthers
Keyword(s):  
Cyclic Loading ◽  
Stress Relaxation ◽  
Constitutive Models ◽  
Large Change ◽  
Time Dependent ◽  
Tangent Modulus ◽  
Strain Rate Effects ◽  
Damage Models ◽  
Filled Elastomers ◽  
Rate Effects

Abstract An extensive set of time-dependent mechanical data was obtained for several filled SBR elastomers, including Mullins experiments, cyclic loading experiments, and stress relaxation. These comprehensive data enable critical evaluation of three classes of constitutive models. Viscoelastic models can naturally describe the hysteresis upon loading/reloading, but are unable to capture the large change in tangent modulus between the initial loading and the modulus just as the specimen is being unloaded. Elastic-damage models can capture the large change in tangent modulus just prior versus subsequent to unloading of a virgin sample, but can only parameterize the hysteresis on cyclic loading and are unable to predict strain rate effects and stress relaxation. A viscoelastic-damage model can predict the large change in tangent modulus upon reversal of the strain, hysteresis, strain rate effects, and stress relaxation; however, viscoelastic-damage models are unable to simultaneously predict the modest amount of hysteresis observed in cyclic experiments and the large amount of stress relaxation observed after loading to large deformations. The analysis indicates that constitutive models that include different deformation mechanics than the traditional elastic, viscoelastic, and damage processes will be needed to describe the full range of mechanical behavior exhibited by carbon black filled elastomers.

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