Beitrag zur Ermittlung der Kräfte beim Eisbrechen unter besonderer Berücksichtigung der Anisotropie des Eises und seiner Versagenseigenschaften unter mehrachsiger Beanspruchung

Content Provider	Semantic Scholar
Author	Häusler, Franz Ulrich
Copyright Year	1989
Abstract	(Title: Contribution to the Evaluation of the Forces at Icebreaking with Particular Consideration of the Anisotropy of lee and it's Failure Properties und er Multiaxial Stresses) For the numerical analysis of icebreaking problems, a planar isotropie elastic-plastic material model is described which represents the mechanical properties of columnargrained sea-ice or sea-ice-like model ice. The failure criterion is considered to be quadratic and dependent on temperature, total porosity and strain rate. Its shape aIlows for the description of the strength dependent on hydrostatic stress. In a case study on columnargrained urea-doped model ice it is investigated if and to what degree useful results can be achieved with this material model. The case study is subdivided into three sections: 1. Evaluation of the material model coefficients for urea-doped model ice by means of uniaxial and multiaxial strength testing. 2. Nonlinear finite element analysis on deformation and yield behaviour of two geometricaIly different model ice covers based on the material model and the above coefficients. 3. Verification of computed results through load testing of two model ice covers. Strong and weak points of the material model are analyzed based on the comparison between tests and computation. Paths of further improvement are discussed. As a means of determining the material model coefficients, reference strengths and reference moduli are described. They aIlow for approximate deduction of the mechanical properties of the ice considered through the parameters temperature, total porosity and strain rate for the various conditions encountered within floating ice covers. It is essential that the effect of temperature on the mechanical properties of the load carrying ice matrix be considered separately. On urea-doped and sodium chloride-doped ice it is demonstrated that the reference strengths and reference moduli are independent of the chemical composition of the dopents entrapped within the ice. This applies at least in as far as the dopents are rejected by the ice lattice thus forming pores. In this context formulae for total porosity evaluation according to Cox and Weeks (1982) are developed for urea-doped as weIl as for sodium chloride-doped ice. In addition it is shown that the reference strengths apply to natural columnar-grained sea-ice also. The reference strengths and reference moduli are also employed to evaluate the material model coefficients for sodium chloride-doped model ice. By means of uniaxial, biaxial and triaxial compressive strengths measured on columnar-grained sodium chloride-doped ice it is demonstrated that the material model represents the strength characteristics of real ice for practicaIly aIl stress states of interest in icebreaking problems with good or at least acceptable accuracy. The triaxial strength testing device with brush-like loading platens developed for uniaxial and multiaxial compressive strength testing is described as weIl as the supplementary equipment for tension strength testing. The essential points in preparation and performance of strength testing are illustrated.
File Format	PDF HTM / HTML
DOI	10.15480/882.911
Alternate Webpage(s)	https://tubdok.tub.tuhh.de/bitstream/11420/913/1/Bericht_Nr.494_F.U.Husler_Beitrag_zur_Ermittlung_der_Krfte_beim_Eisbrechen.pdf
Alternate Webpage(s)	https://doi.org/10.15480/882.911
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article