An application of the MIBSA model to the Little Chief Landslide

2020 ◽  
Author(s):  
Giuseppe Dattola ◽  
Giovanni Battista Crosta ◽  
Thomas Stewart
Keyword(s):  
Mathematical Model ◽  
Water Reservoir ◽  
Material Behavior ◽  
Material Strength ◽  
Failure Behavior ◽  
Model Parameters ◽  
Time To Failure ◽  
Empirical Formulas ◽  
Volume Determination ◽  
Landslide Volume

<p>The prediction of a landslide behavior is fundamental for the design of early warning system (EWS) as well for the hazard and risk assessment. The evaluation of expected landslide volume (or extent), displacement, velocity and acceleration is mandatory. Very often empirical formulas are used for landslide volume determination whereas semi-empirical methods like the inverse velocity approach are used for time to failure definition.</p><p>Various approaches have been proposed in the literature to reproduce the landslide behavior in terms of displacement for landslides which are already in an active state or for which displacement data are available for calibration. Some approaches introduce the material viscosity to reproduce the slow motion of the landslide when the driving factor is the fluctuation of the ground water table. Another strategy consists in using numerical methods in which the material strength reduction is introduced. In other cases more sophisticated constitutive models are employed to reproduce the material behavior.</p><p>In this work, we propose an extension of a simple one dimensional mathematical model which reproduces the post failure behavior considering the landslide as an assembly of blocks interacting between each other and moving along the bedrock. In particular, the model takes into account the shear band mechanical behavior by means of a viscous-plastic model based on the Perzyna’s approach with strain-hardening. The interactions between blocks are modelled by formulating an interaction law which takes into consideration also the tangential effects due to friction along the lateral block boundaries. The forcing factors can be the piezometric level oscillation, the seismic shaking and the oscillation of external water reservoir level.</p><p>To validate the mathematical model the numerical results are compared with the Little Chief Landslide located in the North Western Canada along the upper Columbia River valley. The landslide involves a mass of about 800 million of m<sup>3</sup> with the stable bedrock depth ranging between 100 and 300 meters. This is an extremely slow landslide which has been investigated since 1960’s and for which displacements, piezometric levels and their evaluation in time are available for long time out-wards allowing to test the model. The landslide shows a periodic trend for displacements with cyclic accelerations and stable creeping. This allows for the calibration of the model parameters.</p>

Mechanical Properties and Modeling of Subcutaneous Adipose Tissue: a Comprehensive Review

2021 ◽  
Author(s):  
Zhaonan Sun ◽  
Bronislaw Gepner ◽  
Patrick S. Cottler ◽  
Sang-hyun Lee ◽  
Jason Kerrigan
Keyword(s):  
Mechanical Properties ◽  
Adipose Tissue ◽  
Constitutive Models ◽  
Rate Sensitivity ◽  
Material Behavior ◽  
Failure Behavior ◽  
Model Parameters ◽  
Comprehensive Review ◽  
Nonlinear Stress ◽  
Human Body Models

Abstract Mechanical models of adipose tissue are important for various medical applications including cosmetics, injuries, implantable drug delivery systems, and plastic surgeries, and biomechanical applications such as computational human body models for surgery simulation, and blunt impact trauma. This article presents a comprehensive review of experimental approaches that aimed to characterize the mechanical properties of adipose tissue, and the resulting constitutive models and model parameters identified. In particular, this study examines the material behavior of adipose tissue, including its nonlinear stress-strain relationship, viscoelasticity, strain hardening and softening, rate-sensitivity, anisotropy, preconditioning, failure behavior, and temperature dependency.

scholarly journals Assimilation of Dynamic Combined Finite Discrete Element Methods Using the Ensemble Kalman Filter

2021 ◽  
Vol 11 (7) ◽  
pp. 2898
Author(s):  
Humberto C. Godinez ◽  
Esteban Rougier
Keyword(s):  
Kalman Filter ◽  
Ensemble Kalman Filter ◽  
Failure Modes ◽  
Split Hopkinson Pressure Bar ◽  
Peak Stress ◽  
Discrete Element ◽  
Material Behavior ◽  
Model Parameters ◽  
Hopkinson Pressure Bar ◽  
Parameter Values

Simulation of fracture initiation, propagation, and arrest is a problem of interest for many applications in the scientific community. There are a number of numerical methods used for this purpose, and among the most widely accepted is the combined finite-discrete element method (FDEM). To model fracture with FDEM, material behavior is described by specifying a combination of elastic properties, strengths (in the normal and tangential directions), and energy dissipated in failure modes I and II, which are modeled by incorporating a parameterized softening curve defining a post-peak stress-displacement relationship unique to each material. In this work, we implement a data assimilation method to estimate key model parameter values with the objective of improving the calibration processes for FDEM fracture simulations. Specifically, we implement the ensemble Kalman filter assimilation method to the Hybrid Optimization Software Suite (HOSS), a FDEM-based code which was developed for the simulation of fracture and fragmentation behavior. We present a set of assimilation experiments to match the numerical results obtained for a Split Hopkinson Pressure Bar (SHPB) model with experimental observations for granite. We achieved this by calibrating a subset of model parameters. The results show a steady convergence of the assimilated parameter values towards observed time/stress curves from the SHPB observations. In particular, both tensile and shear strengths seem to be converging faster than the other parameters considered.

Dynamic Characterization and Modeling of Carbon Composite Ballistic Behavior

2016 ◽  
Author(s):  
Chian-Fong Yen ◽  
Robert Kaste ◽  
Jian Yu ◽  
Charles Chih-Tsai Chen ◽  
Nelson Carey
Keyword(s):  
Composite Material ◽  
Progressive Failure ◽  
Laminated Composite ◽  
Carbon Composite ◽  
Ballistic Impact ◽  
Impact Testing ◽  
Material Behavior ◽  
Failure Behavior ◽  
Failure Model ◽  
Carbon Composite Material

Design of the new generation of aircraft is driven by the vastly increased cost of fuel and the resultant imperative for greater fuel efficiency. Carbon fiber composites have been used in aircraft structures to lower weight due to their superior stiffness and strength-to-weight properties. However, carbon composite material behavior under dynamic ballistic and blast loading conditions is relatively unknown. For aviation safety consideration, a computational constitutive model has been used to characterize the progressive failure behavior of carbon laminated composite plates subjected to ballistic impact conditions. Using a meso-mechanics approach, a laminated composite is represented by a collection of selected numbers of representative unidirectional layers with proper layup configurations. The damage progression in a unidirectional layer is assumed to be governed by the strain-rate dependent layer progressive failure model using the continuum damage mechanics approach. The composite failure model has been successfully implemented within LS-DYNA as a user-defined material subroutine. In this paper, the ballistic limit velocity (V50) was established for a series of laminates by ballistic impact testing. Correlation of the predicted and measured V50 values has been conducted to validate the accuracy of the ballistic modeling approach for the selected carbon composite material. The availability of this modeling tool will greatly facilitate the development of carbon composite structures with enhanced ballistic and blast survivability.

scholarly journals Building the space elevator: lessons from biological design

2018 ◽  
Vol 15 (147) ◽  
pp. 20180086 ◽  
Author(s):  
Dan M. Popescu ◽  
Sean X. Sun
Keyword(s):  
Tensile Strength ◽  
Material Strength ◽  
Mathematical Framework ◽  
Time To Failure ◽  
Repair Mechanism ◽  
Engineering Structures ◽  
Biological Design ◽  
Working Stress ◽  
Design Paradigm ◽  
Stress Ratios

One of the biggest perceived challenges in building megastructures, such as the space elevator, is the unavailability of materials with sufficient tensile strength. The presumed necessity of very strong materials stems from a design paradigm which requires structures to operate at a small fraction of their maximum tensile strength (usually, 50% or less). This criterion limits the probability of failure by giving structures sufficient leeway in handling stochastic components, such as variability in material strength and/or external forces. While reasonable for typical engineering structures, low working stress ratios—defined as operating stress as a fraction of ultimate tensile strength—in the case of megastructures are both too stringent and unable to adequately control the failure probability. We draw inspiration from natural biological structures, such as bones, tendons and ligaments, which are made up of smaller substructures and exhibit self-repair, and suggest a design that requires structures to operate at significantly higher stress ratios, while maintaining reliability through a continuous repair mechanism. We outline a mathematical framework for analysing the reliability of structures with components exhibiting probabilistic rupture and repair that depend on their time-in-use (age). Further, we predict time-to-failure distributions for the overall structure. We then apply this framework to the space elevator and find that a high degree of reliability is achievable using currently existing materials, provided it operates at sufficiently high working stress ratios, sustained through an autonomous repair mechanism, implemented via, e.g. robots.

Biomechanics of Soft Tissues: The Role of the Mathematical Model on Material Behavior

2019 ◽  
pp. 301-311
Author(s):  
Carlos Bustamante-Orellana ◽  
Robinson Guachi ◽  
Lorena Guachi-Guachi ◽  
Simone Novelli ◽  
Francesca Campana ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Soft Tissues ◽  
Material Behavior ◽  
The Mathematical Model

scholarly journals Deep search for hydrogen peroxide toward pre- and protostellar objects

2020 ◽  
Vol 636 ◽  
pp. A114
Author(s):  
G. W. Fuchs ◽  
D. Witsch ◽  
D. Herberth ◽  
M. Kempkes ◽  
B. Stanclik ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Solid State ◽  
Water Reservoir ◽  
Reaction Network ◽  
Reaction Scheme ◽  
Young Stellar Objects ◽  
Model Parameters ◽  
Stellar Objects ◽  
Additional Information ◽  
Water Formation

Context. In the laboratory, hydrogen peroxide (HOOH) was proven to be an intermediate product in the solid-state reaction scheme that leads to the formation of water on icy dust grains. When HOOH desorbs from the icy grains, it can be detected in the gas phase. In combination with water detections, it may provide additional information on the water reaction network. Hydrogen peroxide has previously been found toward ρ Oph A. However, further searches for this molecule in other sources failed. Hydrogen peroxide plays a fundamental role in the understanding of solid-state water formation and the overall water reservoir in young stellar objects (YSOs). Without further HOOH detections, it is difficult to assess and develop suitable chemical models that properly take into account the formation of water on icy surfaces. Aims. The objective of this work is to identify HOOH in YSOs and thereby constrain the grain surface water formation hypothesis. Methods. Using an astrochemical model based on previous work in combination with a physical model of YSOs, the sources R CrA-IRS 5A, NGC C1333-IRAS 2A, L1551-IRS 5, and L1544 were identified as suitable candidates for an HOOH detection. Long integration times on the APEX 12 m and IRAM 30 m telescopes were applied to search for HOOH signatures in these sources. Results. None of the four sources under investigation showed convincing spectral signatures of HOOH. The upper limit for HOOH abundance based on the noise level at the frequency positions of this molecule for the source R CrA-IRS 5A was close to the predicted value. For NGC 1333-IRAS 2A, L1544, and L1551-IRS 5, the model overestimated the hydrogen peroxide abundances. Conclusions. HOOH remains an elusive molecule. With only one secure cosmic HOOH source detected so far, namely ρ Oph A, the chemical model parameters for this molecule cannot be sufficiently well determined or confirmed in existing models. Possible reasons for the nondetections of HOOH are discussed.

scholarly journals The identification of a device based on a Peltier element by the least squares method

2020 ◽  
pp. 17-27
Author(s):  
Vladimir Grinkevich ◽  
Keyword(s):  
Mathematical Model ◽  
Least Squares ◽  
Least Squares Method ◽  
Control Object ◽  
Object Identification ◽  
Model Parameters ◽  
Peltier Element ◽  
Transport Delay ◽  
Non Linear ◽  
The Mathematical Model

The evaluation of the mathematical model parameters of a non-linear object with a transport delay is considered in this paper. A temperature controlled stage based on a Peltier element is an identification object in the paper. Several input signal implementations are applied to the input of the identification object. The least squares method is applied for the calculation of the non-linear differential equitation parameters which describe the identification object. The least squares method is used due to its simplicity and the possibility of identification non-linear objects. The parameters values obtained in the process of identification are provided. The plots of temperature changes in the temperature control system with a controller designed based on the mathematical model of the control object obtained as a result of identification are shown. It is found that the mathematical model obtained in the process of identification may be applied to design controllers for non-linear systems, in particular for a temperature stage based on a Peltier element, and for self-tuning controllers. However, the least square method proposed in the paper cannot estimate the transport delay time. Therefore it is required to evaluate the time delay by temperature transient processes. Dynamic object identification is applied when it is required to obtain a mathematical model structure and evaluate the parameters by an input and output control object signal. Also, identification is applied for auto tuning of controllers. A mathematical model of a control object is required to design the controller which is used to provide the required accuracy and stability of control systems. Peltier elements are applied to design low-power and small- size temperature stage . Hot benches based on a Peltier element can provide the desired temperature above and below ambient temperature.

scholarly journals Formulated Mathematical Model for Delayed Particle Flow in Cascaded Sub-Surface Water Reservoirs with Validation on River Flow

2018 ◽  
Author(s):  
Ombaki Richard ◽  
Kerongo Joash ◽  
Okwoyo M. James
Keyword(s):  
Mathematical Model ◽  
Time Delay ◽  
Surface Water ◽  
Discrete Time ◽  
River Flow ◽  
Water Reservoir ◽  
Point Sources ◽  
Water Reservoirs ◽  
Discrete Time Delay ◽  
Mixing Problem

Pollution of sub-surface water reservoirs mainly rivers and streams through contaminated water point sources (CWPS) was studied. The objective was to formulate a discrete time delay mathematical model which describes the dynamics of reservoir pollution using mixing-problem processes that involve single species contaminants such as nitrates, phosphorous and detergents. The concentration  of pollutants was expressed as a function of the inflow and outflow rates using the principle for the conservation of mass. Systems of ODEs generated from principles of mixing problems were refined into a system of DDEs so that the concentration of pollutant leaving the reservoir at time would be determined at some earlier instant, for the delay. The formulated model is a mathematical discrete time delay model which would be used to describe the dynamics of sub-surface water reservoir pollution. The results from the validation of the model were analyzed   to determine how time delays in the mixing processes affect the rate of particle movement in water reservoirs.

scholarly journals Hydrogeological and Hydro Chemical Evaluation of Groundwater in Karbala Region Using Geographic Information System (GIS)

2020 ◽  
Vol 38 (4A) ◽  
pp. 515-522
Author(s):  
Marwa S. Hussein ◽  
Imzahim A. Alwan ◽  
Tariq A. Hussain
Keyword(s):  
Mathematical Model ◽  
System Modeling ◽  
Water Reservoir ◽  
Unconfined Aquifer ◽  
Groundwater Table ◽  
Flow State ◽  
Groundwater Levels ◽  
Chemical Evaluation ◽  
Unsteady Flow Condition ◽  
High Production

The study area is located in the holy governorate of Karbala, Iraq; the research studied a predictive mathematical model of groundwater within Dibdiba Formation and by fifty (50) wells distributed randomly within the boundaries of the study area, all of them fall within the unconfined aquifer. Likewise, there is no component to direct the activity of these wells, where a mathematical model for the study area has been developed using the groundwater system modeling program (GMS v.10). The area was divided into a grid where the dimensions of a single cell ranged from 250m×250m. The model of the steady flow state was adjusted utilizing pressure driven conductivity extending from 9 to 15 m/day with a 0.15 storage coefficient to match the groundwater levels measured with the calculated groundwater table. The model was run for unsteady flow condition in the first scenario with fifty (50) wells and five (5) years. The drawdown in the groundwater tables ranged between (0.05-1.05) m. In the second scenario, the model was run after adding thirty-six (36) wells for five (5) years, groundwater limits 0.15-1.15 meters. The drawdown values are concentrated near wells sites, and the drawdown decline as we move away from the sites of these wells and this reflects the nature of the water reservoir located in the study area, which is characterized by high production where compensation resulting from the operation of the wells decline rapidly by the reservoir. Therefore, the values of the drawdown in elevations appeared very low. The study also showed the possibility of drilling additional wells in this area, depending on this model to benefit from them in the future for different uses.

scholarly journals A mathematical model of common-cold epidemics on Tristan da Cunha

1971 ◽  
Vol 69 (3) ◽  
pp. 423-433 ◽  
Author(s):  
B. J. Hammond ◽  
D. A. J. Tyrrell
Keyword(s):  
Mathematical Model ◽  
Common Cold ◽  
Average Duration ◽  
Model Parameters ◽  
Epidemic Threshold ◽  
Tristan Da Cunha ◽  
Simulation Techniques ◽  
Time Courses ◽  
The Mathematical Model ◽  
Computer Simulation Techniques

SUMMARYRecords of seven common-cold outbreaks on the island of Tristan da Cunha are compared with the corresponding time courses given by the mathematical model of Kermack & McKendrick (1927) and with an alternative model that directly involves a constant average duration of individual infection. Using computer simulation techniques the latter model is shown to be preferred and is then closely matched to the field data to obtain values for the model parameters. Consideration is then given to the intensity of epidemics predicted by the model and to the distribution of the actual epidemics relative to the theoretical epidemic threshold.

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