Download or read book Constitutive Equations and Fracture Models for Sea Ice written by and published by . This book was released on 1996 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final report summarizes research on deformation and fracture models for sea ice. In many cases results are compared with those for freshwater ice. Described first is work on modeling of primary creep for relatively short loading histories, studies on the applicability of linear elastic fracture mechanics to polycrystalline freshwater and sea ice, and finally a study on stress-transmission in polycrystals undergoing grain boundary sliding. Next, emphasis is on characterization of time-dependent deformation behavior of ice from short to very long-time behavior. This behavior requires the use of models that account for broad spectrum viscoelasticity. Linear viscoelasticity theory is used first in order to develop an understanding of how single-crystal creep produces broad-spectrum behavior of polycrystals through the mechanical interaction of single crystals. Guided by these results and then nonequilibrium thermodynamic principles, nonlinear viscoelastic constitutive equations are developed that make direct use of creep compliances predicted from the linear theory of polycrystals. While only theoretical work has been done on this grant, experimental data provided by others have been used to verify some of the predictions. Comparison of theory and experiment appears in some of the publications.
Download or read book Mechanical Behavior of Sea Ice written by Malcolm Mellor and published by . This book was released on 1983 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part of the report provides an introduction to the mechanics of deformable solids, covering the basic ideas of stress and strain, rheology, equilibrium equations, strain/displacement relations, constitutive equations, and failure criteria. Fracture mechanics and fracture toughness are also reviewed briefly. The second part summarizes available data on the mechanical properties of freshwater ice and saline ice, accounting for the influences of strain rate and loading rate, temperature, porosity, salinity, and grain size. Boundary value problems are not dealt with, but there is discussion of some miscellaneous topics, including thermal strains, behavior of brash ice, and pressure ridges. The report was written as a study text for a NATO Advanced Study Institute on Sea/Ice/Air Interactions, and was intended to be used in conjunction with companion texts on related topics. This report was written during the summer of 1981, and thus does not cover all results which appeared after the end of 1981.
Download or read book Mechanical Behavior of Sea Ice written by Cold Regions Research and Engineering Laboratory (U.S.) and published by . This book was released on 1983 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part of the report provides an introduction to the mechanics of deformable solids, covering the basic ideas of stress and strain, rheology, equilibrium equations, strain/displacement relations, constitutive equations, and failure criteria. Fracture mechanics and fracture toughness are also reviewed briefly. The second part summarizes available data on the mechanical properties of freshwater ice and saline ice, accounting for the influences of strain rate and loading rate, temperature, porosity, salinity, and grain size. Boundary value problems are not dealt with, but there is discussion of some miscellaneous topics, including thermal strains, behavior of brash ice, and pressure ridges. The report was written as a study text for a NATO Advanced Study Institute on Sea/Ice/Air Interactions, and was intended to be used in conjunction with companion texts on related topics. This report was written during the summer of 1981, and thus does not cover all results which appeared after the end of 1981.
Download or read book Sea Ice Mechanics Research written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sea Ice Mechanics and Arctic Workshop was held in Anchorage, Alaska, April 25-28, 1995. The workshop focused on current state of the practice and future research needs relative to offshore oil and gas facilities, and also reviewed the results of the U.S. Navy's Office of Naval Research (ONR) Sea Ice Mechanics Initiative (SIMI). SIMI was an Office of Naval Research Accelerated Research Initiative (ARI), spanning the years 1991 to 1996. Its goals were to: understand sea ice constitutive laws and fracture mechanics over the full range of geophysical scales; and determine the scaled response to applied external forces and develop physically based constitutive and fracture models.
Download or read book IUTAM Symposium on Scaling Laws in Ice Mechanics and Ice Dynamics written by J.P. Dempsey and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Volume constitutes the Proceedings of the IUTAM Symposium on 'Scaling Laws in Ice Mechanics and Ice Dynamics', held in Fairbanks, Alaska from 13th to 16th of June 2000. Ice mechanics deals with essentially intact ice: in this discipline, descriptions of the motion and deformation of Arctic/ Antarctic and river/lake ice call for the development of physically based constitutive and fracture models over an enormous range in scale: 0.01 m - 10 km. Ice dynamics, on the other hand, deals with the movement of broken ice: descriptions of an aggregate of ice floes call for accurate modeling of momentum transfer through the sea/ice system, again over an enormous range in scale: 1 km (floe scale) - 500 km (basin scale). For ice mechanics, the emphasis on lab-scale (0.01 - 0.5 m) research con trasts with applications at the scale of order 1 km (ice-structure interaction, icebreaking); many important upscaling questions remain to be explored.
Download or read book Drift Deformation and Fracture of Sea Ice written by Jerome Weiss and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea ice is a major component of polar environments, especially in the Arctic where it covers the entire Arctic Ocean throughout most of the year. However, in the context of climate change, the Arctic sea ice cover has been declining significantly over the last decades, either in terms of its concentration or thickness. The sea ice cover evolution and climate change are strongly coupled through the albedo positive feedback, thus possibly explaining the Arctic amplification of climate warming. In addition to thermodynamics, sea ice kinematics (drift, deformation) appears as an essential factor in the evolution of the ice cover through a reduction of the average ice age (and consequently of the cover's thickness), or ice export out of the Arctic. This is a first motivation for a better understanding of the kinematical and mechanical processes of sea ice. A more upstream, theoretical motivation is a better understanding of the brittle deformation of geophysical objects across a wide range of scales. Indeed, owing to its very strong kinematics, compared e.g. to the Earth’s crust, an unrivaled kinematical data set is available for sea ice from in situ (e.g. drifting buoys) or satellite observations. Here, we review the recent advances in the understanding of sea ice drift, deformation and fracturing obtained from these data. We focus particularly on the scaling properties in time and scale that characterize these processes, and we emphasize the analogies that can be drawn from the deformation of the Earth’s crust. These scaling properties, which are the signature of long-range elastic interactions within the cover, constrain future developments in the modeling of sea ice mechanics. We also show that kinematical and rheological variables such as average velocity, average strain-rate or strength have significantly changed over the last decades, accompanying and actually accelerating the Arctic sea ice decline.
Download or read book Ice Mechanics for Geophysical and Civil Engineering Applications written by Ryszard Staroszczyk and published by Springer. This book was released on 2018-12-29 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the concepts and tools of ice mechanics, together with examples of their application in the fields of glaciology, climate research and civil engineering in cold regions. It starts with an account of the most important physical properties of sea and polar ice treated as an anisotropic polycrystalline material, and reviews relevant field observations and experimental measurements. The book focuses on theoretical descriptions of the material behaviour of ice in different stress, deformation and deformation-rate regimes on spatial scales ranging from single ice crystals, those typical in civil engineering applications, up to scales of thousands of kilometres, characteristic of large, grounded polar ice caps in Antarctica and Greenland. In addition, it offers a range of numerical formulations based on either discrete (finite-element, finite-difference and smoothed particle hydrodynamics) methods or asymptotic expansion methods, which have been used by geophysicists, theoretical glaciologists and civil engineers to simulate the behaviour of ice in a number of problems of importance to glaciology and civil engineering, and discusses the results of these simulations. The book is intended for scientists, engineers and graduate students interested in mathematical and numerical modelling of a wide variety of geophysical and civil engineering problems involving natural ice.
Download or read book Fracture of Lake and Sea Ice written by Wilford Frank Weeks and published by . This book was released on 1969 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increased activity in cold regions has made a thorough understanding of fracture in lake and sea ice quite desirable, inasmuch as this information has application to a number of problems of geophysical as well as engineering importance. This survey starts with a discussion of the structure of ice I and the macro- and microstructure of sea and lake ice as well as their chemistry and phase relations. Recent work on the direct observation of dislocations as well as the formation of cracks in ice is summarized. Formal ice-brine-air models for analyzing variations in ice strength are also reviewed. The results of the different types of tests are discussed and compared (compressive, indentation, direct and ring-tension, small beam flexure and in situ cantilevers and simple beams, shear, and impact). Scale effects are considered as well as the rapid strength deterioration experienced by ice sheets in the spring. Finally, a number of recommendations are made concerning future research in this field. (Author).
Download or read book Ice engineering written by M. G. Katona and published by . This book was released on 1973 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing operational use od ice areas in polar regions has heightened the requirement for improved knowledge and techniques to analyze the behavior of sea ice. Previous studies on elastic behavior are reviewed with emphasis placed on plate analysis. Classical plate theory and the finite element method are compared in analyzing ice plates, with special attention given to sea-ice airfields. Since elastic analysis is not totally representative of actual ice behavior, a general formulation is presented which gives the assumptions and procedures for both viscoelastic and nonlinear domains of sea-ice behavior. A laboratory program is being initiated to determine material properties that are necessary to extend sea-ice analysis into the inelastic range. (Author).
Download or read book Numerical Models of Oceans and Oceanic Processes written by Lakshmi H. Kantha and published by Elsevier. This book was released on 2000-08-08 with total page 981 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oceans play a pivotal role in our weather and climate. Ocean-borne commerce is vital to our increasingly close-knit global community. Yet we do not fully understand the intricate details of how they function, how they interact with the atmosphere, and what the limits are to their biological productivity and their tolerance to wastes. While satellites are helping us to fill in the gaps, numerical ocean models are playing an important role in increasing our ability to comprehend oceanic processes, monitor the current state of the oceans, and to a limited extent, even predict their future state.Numerical Models of Oceans and Oceanic Processes is a survey of the current state of knowledge in this field. It brings together a discussion of salient oceanic dynamics and processes, numerical solution methods, and ocean models to provide a comprehensive treatment of the topic. Starting with elementary concepts in ocean dynamics, it deals with equatorial, mid-latitude, high latitude, and coastal dynamics from the perspective of a modeler. A comprehensive and up-to-date chapter on tides is also included. This is followed by a discussion of different kinds of numerical ocean models and the pre- and post-processing requirements and techniques. Air-sea and ice-ocean coupled models are described, as well as data assimilation and nowcast/forecasts. Comprehensive appendices on wavelet transforms and empirical orthogonal functions are also included.This comprehensive and up-to-date survey of the field should be of interest to oceanographers, atmospheric scientists, and climatologists. While some prior knowledge of oceans and numerical modeling is helpful, the book includes an overview of enough elementary material so that along with its companion volume, Small Scale Processes in Geophysical Flows, it should be useful to both students new to the field and practicing professionals. * Comprehensive and up-to-date review* Useful for a two-semester (or one-semester on selected topics) graduate level course* Valuable reference on the topic* Essential for a better understanding of weather and climate
Download or read book Sea Ice Mechanics Research Progress written by and published by . This book was released on 1997 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: The architecture for a new large scale (5 to 100 km, 1 hour to 1 day) sea ice dynamics model based on an anisotropic constitutive law is presented here. This architecture accounts directly for refrozen lead systems in the pack ice strength (with an anisotropic failure surface) and in the ice thickness distribution (with an oriented thickness distribution). The lower limit (5 km) of the model resolution is controlled by the fracture spacing of old, thicker ice and the maximum lead width. The upper limit of the model resolution (100 km) is controlled by curvature in the lead directions and variations in the lead width. These in turn are controlled by the variations in internal ice stress due to driving forces (winds and currents), which set the time resolution. This architecture features abrupt changes in the failure surface and the associated flow rule that cannot be averaged over a time step. In addition, the principal stress normal to a new lead must be zero as it opens. This model has sub-scale simulations that allow for the inclusion of phenomena such as ridging, rafting, buckling, and fracture on the behavior of the ice. With this new ice constitutive law, it is possible to directly test the ice failure strength, plastic flow rule, and ice thickness distribution. The data most useful for this testing come from ice stress and position buoys together with SAR deformation data. Some data comparisons have already been made.
Download or read book Ice Structure Interaction written by Stephen J. Jones and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt: IUTAM-IAHR Symposium on Ice-Structure Interaction Professor Bez Tabarrok, Chairman of the Canadian National Committee (CNC) of the International Union of Theoretical and Applied Mechanics (IUTAM) invited Professor Derek Muggeridge to organize a symposium on ice structure interaction. Dr. Muggeridge readily agreed and prepared a proposal that was endorsed by the CNC and presented to the General Assembly Meeting of IUTAM for their consideration. This Assembly gave its approval and provided the local organizing committee with the names of individuals who were willing to serve on the Scientific Committee. Dr. Muggeridge became chairman of this committee and Dr. Ian Jordaan became co-chairman of this committee as well as chairman of the local organizing committee. The symposium followed the very successful previous meeting, chaired by Professor P. Tryde in Copenhagen, by ten years. Both symposia uti lized Springer-Verlag to publish their proceedings. The Faculty of En gineering and Applied Science at Memorial University of Newfoundland were particul{lXly pleased to host this prestigious symposium as it marked the twentieth anniversary of its Ocean Engineering Research Centre.
Download or read book The Johannes Weertman Symposium written by R. J. Arsenault and published by Minerals, Metals, & Materials Society. This book was released on 1996 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume documents the proceedings of the symposium held to honor Professor Johannes Weertman on his 70th birthday. The chapter topics concentrate on research areas in which Prof. Weertman has made numerous notable contributions, including high temperature deformation, fatigue and fracture plastic deformation of ice, and dynamic plasticity.
Download or read book Constitutive Laws for Sea Ice Dynamics Models written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The long term goal of my research is to develop sea ice dynamics models that describe behavior on kilometer scales and larger, and to base these models on the smaller scale physical processes known to control leading, rafting, and ridging. Three objectives were (1) to continue development of the new anisotropic plasticity constitutive law for large scale sea ice behavior, (2) to analyze data from controlled-load tests conducted during SIMI, and (3) to formulate constitutive laws and solution methods a heterogeneous multiscale material using micromechanics of random media.
Download or read book Fracture Angles in Numerical Simulations of Sea Ice with Viscous plastic Rheologies written by Damien Ringeisen and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea ice is an essential component of the climate system because it modulates the exchange of energy between the ocean and the atmosphere. Under stress from wind and ocean currents, sea ice deforms constantly. Sea ice deformation takes the shape of narrow lines, the Linear Kinematic Features (LKFs). LKFs influence the heat transfer, mass balance, and sea ice dynamics, so LKFs should be accurately represented in high-resolution climate models. Sea ice is commonly modeled using viscous-plastic (VP) rheologies defined by a yield curve and a flow rule. Recent work showed that VP sea ice models explicitly create LKFs but overestimate their intersection angles. This thesis aims to investigate the link between the angles of fracture in sea ice models and the parametrization of the sea ice internal stresses using idealized compression experiments. Three questions are addressed: Which parameters of the VP rheologies influence the fracture angle? Which theoretical framework explains this influence? Which rheologies should be used to simulate intersection angles at the observed range? With the commonly used standard VP rheology with an elliptical yield curve and a normal flow rule, the fracture angles are linked to the yield curve's elliptical shape. Because of this shape, this rheology cannot create sea ice fracture angles more acute than 30 degrees in uniaxial compression, even by changing the aspect of the ellipse. The classical coulombic theory predicts the angle of fracture accurately when adapted to the context of sea ice modeling. A new rheology with an elliptical yield curve and a non-normal flow rule shows that fracture angles are also sensitive to the orientation of the flow rule. Using this new rheology allows creating fracture angles as low as 22 degrees in uniaxial compression. A theory based on the angle of dilatancy and observations of granular materials predicts precisely the simulated angles. Alternative rheologies can create fracture angles lower than 30 degrees. With Mohr--Coulomb yield curves, fracture angles are well predicted by joining the concepts of coulombic friction and angle of dilatancy. Teardrop and Parabolic lens yield curves create small angles of fracture in uni-axial compression when used with small tensile strength. Using a more realistic sea ice cover with heterogeneity, failure under deformation takes the form of a network of fracture lines. The choice of rheology strongly influences the angle of fracture in this network. Two rheologies are suitable candidates to decrease the fracture angles in sea ice VP models. In conclusion, fracture angles in sea ice models are determined by the properties of the VP rheology and can be accurately predicted using fracture orientation theory. Changing the rheology can reduce the fracture angles in sea ice simulations. With the results presented in this thesis, new rheologies could be inferred from observations to represent sea ice fracture more realistically.
Download or read book Creep and Fracture of Ice written by Erland M. Schulson and published by Cambridge University Press. This book was released on 2009-04-30 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first complete account of the physics of the creep and fracture of ice, for graduates, engineers and scientists.
Download or read book Fracture of Lake and Sea Ice written by Cold Regions Research and Engineering Laboratory (U.S.) and published by . This book was released on 1971 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
