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Author: D. E. Nevel Publisher: ISBN: Category : Ice Languages : en Pages : 122
Book Description
The problem investigated in this thesis is the prediction of the deflection and stresses in a floating ice sheet under loads which act over a long period of time. This problem is currently important for oil exploration offshore in the Arctic. A review of analytical methods for predicting the bearing capacity of an ice sheet is given. The problem is formulated by assuming the ice is isotropic with a constant Poisson's ratio. The shear modulus is assumed to obey a linear viscoelastic model. The specific model selected is a series of one Maxwell model and two Voigt models. One of the Voigt models has a negative spring constant which produces tertiary creep. The ice model exhibits a primary, secondary, and tertiary creep response, similar to that observed in uniaxial creep tests of ice. The material properties in the viscoelastic model may be a function of the vertical position in the ice sheet, but all these material properties must be proportional to the same function of position. Using the thin-plate theory for the floating ice sheet, the solution is obtained for the deflection and stresses in the ice sheet for primary, secondary, and tertiary creep regions. It is then shown that for a load that is not distributed over a large area, the time-dependent part of the deflection and stresses is relatively independent of the load's distribution. For the elastic case, the stress significantly depends upon the load's distribution. Results are given for the deflection and stresses as a function of time and distance from the load. The maximum deflection and stresses occur at the center of the load. At this point the deflection increases with time, while the stresses decrease; i.e., the stresses relax. (Author).
Author: D. E. Nevel Publisher: ISBN: Category : Ice Languages : en Pages : 122
Book Description
The problem investigated in this thesis is the prediction of the deflection and stresses in a floating ice sheet under loads which act over a long period of time. This problem is currently important for oil exploration offshore in the Arctic. A review of analytical methods for predicting the bearing capacity of an ice sheet is given. The problem is formulated by assuming the ice is isotropic with a constant Poisson's ratio. The shear modulus is assumed to obey a linear viscoelastic model. The specific model selected is a series of one Maxwell model and two Voigt models. One of the Voigt models has a negative spring constant which produces tertiary creep. The ice model exhibits a primary, secondary, and tertiary creep response, similar to that observed in uniaxial creep tests of ice. The material properties in the viscoelastic model may be a function of the vertical position in the ice sheet, but all these material properties must be proportional to the same function of position. Using the thin-plate theory for the floating ice sheet, the solution is obtained for the deflection and stresses in the ice sheet for primary, secondary, and tertiary creep regions. It is then shown that for a load that is not distributed over a large area, the time-dependent part of the deflection and stresses is relatively independent of the load's distribution. For the elastic case, the stress significantly depends upon the load's distribution. Results are given for the deflection and stresses as a function of time and distance from the load. The maximum deflection and stresses occur at the center of the load. At this point the deflection increases with time, while the stresses decrease; i.e., the stresses relax. (Author).
Author: Arnold D. Kerr Publisher: ISBN: Category : Ice Languages : en Pages : 52
Book Description
This report contains a critical survey of the literature on the bearing capacity of floating ice plates. It consists of a discussion of general questions, a critical survey of analytical attempts to determine the bearing capacity of floating ice plates, and a survey of field and laboratory tests on floating ice plates and their relation to the analytical results. The paper concludes with a systematic summary of the results, a discussion of observed shortcomings, and suggestions for needed investigations.
Author: P. Tryde Publisher: Springer Science & Business Media ISBN: 3642814344 Category : Science Languages : en Pages : 392
Book Description
In the programme of the symposium was written: "The International Union of Theoretical and Applied Me chanics has taken the initiative to organize the sympo sium. As the name of IUTAM implies, the organization brings forward achievements within the field of theore tical mechanics for application in science and engineer ing. According to the rules of IUTAM that only invited persons can attend, all lecturers and participants have been ap pOinted by the members of the scientific committee. To facilitate contact among the attending persons, it has been decided to restrict the total number to 85 persons including the lecturers. Only one session is planned, making it possible for everybody to attend all lectures. Most scientists and engineers have realized that the knowledge attained by extensive basic research is essen tial in order to solve technological problems. In the process of acquiring this knowledge we often fail to un derstand that scientific progress is only achieved by two main principles: (1) By studying the scientific litera ture and applying or improving the theories in order to predict behaviour and forces correctly, or (2) by re jecting existing theories and developing new ways to cope with the problem, resulting in a more differenti ated and, hopefully, more exact theory. Ice seems to be a simple material, but it is in fact so complex and strange that it is only in the latest dec ades that we have come to know some of the natural laws governing its behaviour.
Author: K. Hutter Publisher: Springer ISBN: 9401511675 Category : Science Languages : en Pages : 535
Book Description
The purpose and scope of this book on theoretical glaciology is outlined in the Introduction. Its aim is to study the theoretical aspects of'ice mechanics' and the 'dynamics of ice masses in a geophysical environment. For the mature reader, the book can serve as an introduction to glaciology. How ever, this is not what I would regard as advisible. Glaciology is an inter disciplinary science in which many special scientific disciplines play their part, from descriptive geography to fairly abstract mathematics. Advance ment will evolve from a merger of two or more branches of scientific specialization. In the last 20 years, several researchers in different fields of glaciology have written books emphasizing the aspects of their specialities and I have listed some which are known to me at the end of the Introduction. When glancing through these books, one recognizes that the mathematical aspects of glaciology are generally glossed over and, to date, there seems to be nothing available which concentrates on these. Therefore, I have written this book in an effort to close the gap and no apologies are offered for the mathematical emphasis. Rather, I believe that this neglect has, to a certain extent, aggra vated progress in the modelling of glaciology problems.
Author: Roger LeB. Hooke Publisher: Cambridge University Press ISBN: 1108427340 Category : Business & Economics Languages : en Pages : 537
Book Description
The principles of glacier physics are developed from basic laws in this up-to-date third edition for advanced students and researchers.
Author: W. F. Weeks Publisher: ISBN: Category : Ice mechanics Languages : en Pages : 100
Book Description
The review discusses the state of thinking of each of the main national groups investigating sea ice and gives an overall appraisal of the field as a whole. Emphasis is placed on (1) the physical basis for interpreting sea ice strength (phase relations, air volume, and structural considerations), (2) theoretical considerations (strength models, air bubbles and salt reinforcement, and interrelations between growth conditions and strength), (3) experimental results (tensile, flexural, shear, and compressive strength, elastic modulus, shear modulus and Poisson's ratio, time dependent effects, and creep), and (4) plate characteristics. The paper includes a review of problems in sea ice investigations, relates the chemical, crystallographic, mechanical, and physical aspects involved, and concludes by showing how to utilize this knowledge to solve practical problems. (Author).
Author: D. E. Nevel Publisher: ISBN: Category : Elastic plates and shells Languages : en Pages : 20
Book Description
The solution for the vibration of an elastic plate floating on water is developed. The water is assumed to be incompressible and to have irrotational flow. In free vibration upon release of the plate, the maximum negative rebound of the deflection is 25%. For forced vibration, the steady state part of the solution shows that there is a frequency at which the deflection is a maximum. The stresses become a maximum at a frequency higher than the one for deflection. These critical frequencies depend upon the plate's characteristic length and the depth of the water. For most situations the critical frequency for stress is less than 0.2 cycle per second. At this critical frequency the stresses are amplified over the static case by a factor less than 10%. (Author).
Author: D. E. Nevel Publisher: ISBN: Category : Materials Languages : en Pages : 24
Book Description
The paper considers a load moving with a constant velocity across an ice sheet that is floating on water. The ice sheet is assumed to be an isotropic, elastic, thin plate extending to infinity. The water is assumed to be inviscous, incompressible, and of a constant depth. The dynamic equations describing this ice-water system are solved for the steady state solution. Both a concentrated load and a uniform load distributed over a circular area are considered. The velocity which causes resonance is determined. The deflection and stress directly under the load are numerically evaluated.
Author: D. E. Nevel
Author: D. E. Nevel
Author: Arnold D. Kerr
Author: Shunsuke Takagi
Author: P. Tryde
Author: K. Hutter
Author: Cold Regions Research and Engineering Laboratory (U.S.)
Author: Roger LeB. Hooke
Author: W. F. Weeks
Author: D. E. Nevel
Author: D. E. Nevel