| Summary: | Defining the compressive strength of ice is difficult. In this thesis the measuring of the compressive strength both in model and full-scale is discussed. With model tests it is possible to research the impact of ice on ships and offshore structures. The model ice is made to correspond sea ice. The most important characters are flexural strength and thickness. The compressive strength of model ice is significantly smaller than expected. The crystal structure of model ice differs from sea ice. The differences in measurements between model and full-scale are recognized but model test can still be considered reliable because the analysis is based on a great amount of model and full-scale references. This thesis focuses on finding reasons for the significantly lower compressive strength values of model ice. The thesis is divided into two parts. In the beginning there is a literature survey about the compressive strength of ice, measuring the quantity and its significance of the impact of ice on ships and offshore structures. The latter part is an empirical study that compares two different measuring equipments used for defining the compressive strength. There are three major tasks. First to find a valid value for the compressive strength measured from sea ice to be used as a numerical comparison in model tests. The second task is to find the best solution available for model scale measurements. Thirdly to discuss the low compressive strength of the ice in a model basin. Jään puristuslujuus on vaikeasti mitattava suure. Tässä työssä perehdytään jään puristuslujuuden mittaukseen täys- ja mallimittakaavassa. Jäämallikokeilla voidaan pienessä mittakaavassa tutkia meriteknisen rakenteen ja jään kohtaamiseen liittyviä ilmiöitä. Mallijää valmistetaan vastaamaan merijäätä mallikokeiden kannalta tärkeimmiltä ominaisuuksiltaan, jotka ovat jään paksuus ja taivutuslujuus. Mallijäätä ei vielä ole onnistuttu valmistamaan sellaiseksi, että sekä taivutus- että puristuslujuus skaalautuisivat oikein samanaikaisesti, vaan silloin ...
|
|---|