Ice-Structure Interaction Analysis: Inverse Ice Force Prediction for Stiffened Plate and Dynamic Simulation

Ice Structure Interaction;Dynamic Analysis;Stiffened Plate Analysis;Fourier Analysis;Finite Element Analysis;Strain Gauge;Inverse Force;Naval Architecture and Marine Engineering;Engineering;Naval Architecture & Marine Engineering

Zhang, YuxiVlahopoulos, Nickolas ;

University of Michigan

关键词: Ice Structure Interaction;    Dynamic Analysis;    Stiffened Plate Analysis;    Fourier Analysis;    Finite Element Analysis;    Strain Gauge;    Inverse Force;    Naval Architecture and Marine Engineering;    Engineering;    Naval Architecture & Marine Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/146006/yuxiz_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Offshore regions of the Arctic and the Great Lakes hold valuable resources in many respects for harvesting energy and serving as important shipping lanes. Ice loading poses a threat to structures in these regions with high local pressure and various failure modes. It is thus essential to evaluate the ice peak loadings using limited and site-specific data. This thesis aims to better predict the peak ice loading by developing an efficient inverse ice loading prediction methodology and accurate stiffened plate analysis for marine structure design. Additionally, the behavior of the ice-structure interaction is studied mathematically to understand the cyclic dynamic ice-loading applied on offshore structures during continuous ice crushing.Multiple inverse algorithms are presented for calculating the variable ice pressure acting on a stiffened steel plate. The analytical models are formulated to calculate the quasi-static pressure caused by contact of lake ice driven primarily by thermal expansion and winds. Loading pressures are calculated using strain measurements from a stiffened plate installed on a Keweenaw Peninsula lighthouse in Lake Superior. The ice sheet was essentially stationary through the winter months. The linear relationships between pressure and strain values are obtained by both strip beam theory and orthotropic plate theory. The inverse solutions are by nature not necessarily unique. Two inverse approaches using orthotropic plate theory show results with satisfying accuracy and efficiency compared to the finite element analysis. In addition, laboratory calibration and an examination using the recorded data from field measurements exhibit the effectiveness of the presented approach.Continuous ice brittle crushing occurs in the movement of an ice sheet against an offshore structure. Matlock’s ice-structure interaction model is used to simulate the behavior of the ice crushing by modeling ice teeth indentation contacting a spring-mass-dashpot structure. The dynamic behavior of the model is studied using Fourier analysis to predict the response of specific periodicity. The time histories of tooth deflections are expressed through non-linear dynamic equations. The kinematic initial conditions can be predicted at targeted periodicity via the Fourier analysis. Given a representative offshore wind tower system, the first mode shape of the physical system is calculated as input for the ice-structure interaction model as an extended validation. The amplitudes of the structural dynamic vibrations predicted by the analytical model at specific periodicity are compared to the mathematical numerical simulations.A discrete energy method is applied to accurately calculate the deformation of either unidirectional or cross-gridded stiffened panels. This approach obtains the strain energy of the plate and stiffeners using double Fourier series for the displacement fields. Two models are described assuming different reference planes. The first model presumes that the reference planes are located at the effective centroids which are calculated from the cross-sectional properties. The second model formulates the in-plane displacement fields at the mid-plane of the plate. The plate is simply supported along all four edges at the effective centroids for the first model, and at the mid-plane of the plate for the second model. Both methods accurately capture the deformations between stiffeners and the second model eliminates the complicated calculation for effective breadth which is an unavoidable effort for stiffened plate analysis using conventional orthotropic plate theory. The methods presented provide efficient design tools and can be applied to light weight structural design in various fields.