Evaluation of ice induced loads on ships in compressive ice

Filipović, Antonio (2014) Evaluation of ice induced loads on ships in compressive ice. = Master's thesis (Bologna) , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Parunov, Joško.

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Abstract (Croatian)

Ice covered sea areas was given more attention during the last decade due to the increased natural resource exploitation and new transport routes. Merchant ships with a long parallel midbody section aren't suitable for winter conditions. Compressive ice can cause pressure to the side of the ship and ship can get stuck in ice. Compressive ice is one of the greatest hazards for maritime traffic in winter conditions, yet little is known about the effects and forces involved. Within project called SAFEWI\N ice model tests were conducted in the ice basin of Aalto University in compressive ice field. Tests included six test series with varying ice thickness and compression levels. The model adopted in the tests was a bulk carrier with a bulbous bow and a long parallel midship section. In this thesis the loads on the ship model in compressive ice has been studied. Measurement data are gathered from the load panels at the midship, bow shoulder and load sensors on the pusher plates for level ice tests and closing channel tests. Further, natural sea ice is highly heterogeneous and causes high scattering in any measured values. This study seeks to find the maximum line loads caused by compressive ice field and compare those with ones calculated by ISO code to verify ISO code reliability. As a limitation, loads due to ice ridges are not investigated within this thesis. An analyzed results show that ice thickness has a major influence on the loads. Compression level has influence on loads, too, but significantly less than thickness. Further, line load curves for different ice thicknesses are presented and compared with ISO code. The calculated values represented the results of the model tests fairly well. Moreover, measurements at midship load panel show that weak compression was occurred in 3 out of 6 compressive level ice tests (loads were significantly smaller than in other tests). Comparing compressive level ice and closing channel measurements, loads at the bow shoulder and midship have been found to be higher in closing channel tests.

Abstract

"Područja prekrivena ledom od velikog su interesa zadnjih desetljeća zbog povećane eksploatacije prirodnih resursa kao i zbog novih transportnih ruta. Trgovački brodovi s dugim paralelnim srednjakom nisu pogodni za zimske uvjete. Sabijajući led može izazvati pritisak na boku broda i brod može zapeti u ledu. Sabijajući led je jedna od najvećih opasnosti za pomorski promet u zimskim uvjetima, no ipak malo se znao o efektima i silama vezanim za taj proces. U sklopu projekta nazvanog ""SAFEWIN"", obavljena su modelska ispitivanja u bazenu s ledom Aalto Sveučilišta u polju sabijenog leda. Ispitivanja uključuju šest ispitnih serija s različitim debljinama leda i stupnjem sabijanja. Model korišten u ispitivanjima je brod za rasuti teret s pramčanim bulbom i dugim paralelnim srednjakom. U ovom radu su proučavana opterećenja na model u sabijajućem ledu. Upotrijebljeni mjerni podaci su prikupljeni s mjernih panela na paralelnom srednjaku, pramčanom ramenu i senzorima opterećenja na potisnim pločama za ispitivanja nivo leda (eng. level ice tests) i ispitivanja kanala koji se zatvara (eng. closing channel tests). Prirodni morski led je prilično heterogen i uzrokuje veliko rasipanje izmjerenih vrijednosti. Ovim radom se pokušavaju pronaći maksimalne krivulje opterećenja uzrokovane sabijajućim poljem leda i usporediti ih s onima dobivenima prema ISO propisima da bi se potvrdila pouzdanost tih propisa. Kao ograničenje, opterećenja uslijed ledenih grebena nisu promatrana u ovom radu. Analizirani rezultati pokazuju da debljina leda ima najveći utjecaj na opterećenja. Stupanj sabijanja također ima utjecaj, ali značajno manje nego debljina leda. Nadalje, prikazane su linije opterećenja za različite debljine leda i uspoređene su s ISO propisima. Izračunate vrijednosti jako dobro aproksimiraju rezultate modelskih ispitivanja. Povrh toga, mjerenja na opterećenim panelima na paralelnom srednjaku pokazuju da se slabo sabijanje dogodilo u 3 od 6 ispitivanja (opterećenja su bila značajno manja nego u drugim ispitivanjima). Uspoređujući mjerenja sabijajućeg nivo leda i zatvarajućeg kanala, opterećenja na pramčanom ramenu i paralelnom srednjaku su bila viša u ispitivanima zatvrajućeg kanala."

Item Type: Thesis (Master's thesis (Bologna))
Uncontrolled Keywords: compressive ice; ice loads; ice model testing; ship-ice interaction; line load curve; full-scale load
Keywords (Croatian): sabijajući led; opterećenje od leda; modelska ispitivanja s ledom; međudjelovanje brod-led; krivulja linijskog opterećenja; opterećenja u punom mjerilo
Date Deposited: 22 Sep 2014 18:00
Last Modified: 16 Oct 2015 12:46
URI: http://repozitorij.fsb.hr/id/eprint/2783

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