Sensitivity Analysis of Impact Velocity and Added Mass for Iceberg/Bergy-Bit Impact with Fixed Offshore Structure
Iceberg/Bergy-bit impact with ships and offshore structures is an important consideration to govern design load in ice covered regions. Uncertainty in estimating impact load lies due to size and shape of the iceberg, ice properties and associated environmental effects. Moreover hydrodynamic interaction in close proximity also influences the impact load to a great extent which is still uncertain. Various full scale impact tests showed lower ice loads than would be expected with existing
... base. Model scale experiments also have shown different phenomena such as negative wave drift force, fluid cushioning, shadowing, reduction in impact velocity, and hydrodynamic damping. Impact velocity and added mass are two important parameters which influence the hydrodynamic interaction in close vicinity. A simplified iceberg impact model has been developed based on limited energy method and the effects of impact velocity and added mass are identified through sensitivity analysis using Monte-Carlo simulation. The results show significant effects of impact velocity and added mass on maximum impact load estimation which is more pronounced for impact velocity. A realistic impact scenario is demonstrated considering combined effects of increase in added mass and reduction in impact velocity. Statistical Design of Experiments (DOE) is also applied to a bergy bit impact study which reveals the sensitivity of the significant control parameters and their interaction effects on the response. DOE analysis reveals that ice crushing strength is another significant factor besides impact velocity and added mass coefficient that contributes to the maximum impact load estimation.