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Experimental and numerical investigation of brittle ice crushing loads
Citation Link: https://doi.org/10.15480/882.4923
Publikationstyp
Doctoral Thesis
Date Issued
2023
Sprache
English
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2022-12-16
TORE-DOI
Citation
Technische Universität Hamburg (2023)
Ice loads pose a significant risk for ship operation in ice covered waters. At low strain rates, the ice behaves ductile, whereas at high strain rates it reacts in brittle manner. This thesis focuses on the brittle mode, which is the dominating mode for ship-ice interactions. A multitude of experimental data and numerical approaches for the simulation of ice can be found in the literature. Nevertheless, versatile and profound validated simulation techniques are currently missing to access the consequences of an iceberg collision or ice floe impact.
Hence, in this thesis the new experimental set-up of the ice extrusion tests for the investigation of ice crushing loads is presented and a finite element model for the simulation of brittle ice-structure interaction problems is developed. During the comprehensive ice extrusion test campaign confined ice specimens were pushed against quasi rigid or full-scale ship structures. The obtained results reveal that the failure mode depends mainly on the test speed, while the confinement of ice mainly determines the load level.
The core objective of the developed Mohr-Coulomb Nodal Split (MCNS) ice material model is to enable efficient physical based ice-structure interaction simulations. Unlike previously existing ice models, the MCNS model takes spalling and crushing into account, which significantly increases the versatility and reliability of the approach. The confinement effect on the crushing strength and the anisotropic failure behaviour of the ice is modelled by the Mohr-Coulomb material model. To preserve mass and energy as much as possible, the node splitting technique is applied in addition to the element erosion technique. To validate the findings of the model, the simulated maximum ice forces and contact pressures are compared with small- and large-scale ice extrusion experiments and double pendulum tests. During validation, the MCNS model shows a very good agreement with these experimental results.
Finally, a procedure is proposed to simulate full-scale ship-ice collisions on basis of the given methodologies and experimental results.
Hence, in this thesis the new experimental set-up of the ice extrusion tests for the investigation of ice crushing loads is presented and a finite element model for the simulation of brittle ice-structure interaction problems is developed. During the comprehensive ice extrusion test campaign confined ice specimens were pushed against quasi rigid or full-scale ship structures. The obtained results reveal that the failure mode depends mainly on the test speed, while the confinement of ice mainly determines the load level.
The core objective of the developed Mohr-Coulomb Nodal Split (MCNS) ice material model is to enable efficient physical based ice-structure interaction simulations. Unlike previously existing ice models, the MCNS model takes spalling and crushing into account, which significantly increases the versatility and reliability of the approach. The confinement effect on the crushing strength and the anisotropic failure behaviour of the ice is modelled by the Mohr-Coulomb material model. To preserve mass and energy as much as possible, the node splitting technique is applied in addition to the element erosion technique. To validate the findings of the model, the simulated maximum ice forces and contact pressures are compared with small- and large-scale ice extrusion experiments and double pendulum tests. During validation, the MCNS model shows a very good agreement with these experimental results.
Finally, a procedure is proposed to simulate full-scale ship-ice collisions on basis of the given methodologies and experimental results.
Subjects
Ice mechanics
Ice-structure interaction
Finite element analysis
Ice breaking ships
Experiment
DDC Class
620: Ingenieurwissenschaften
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Herrnring_Hauke_Experimental and Numerical Investigation of Brittle Ice Crushing Loads_publish.pdf
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