Cracking pattern of indented ice sheet bending failures

2021 ◽  
pp. 1-14
Author(s):  
Ning Xu ◽  
Haisheng Zhang ◽  
Yihe Wang
Keyword(s):  
Real Time ◽  
Ice Sheet ◽  
Offshore Structures ◽  
Analytical Models ◽  
Sheet Bending ◽  
Theory Of Plates ◽  
Pattern Determination ◽  
Ice Floes ◽  
Cracking Pattern ◽  
Real Time Simulations

Abstract Ice sheet bending failures have been investigated extensively for ice loads on conical offshore structures and icebreakers in arctic regions. Most previous theoretical studies focus on bending failures of semi-infinite level ice, ice wedges, or finite-sized rectangular ice floes. For indented ice sheet bending failures, Nevel (1992) and Lau (2004) developed analytical ice load models by assuming a radial-before-circumferential cracking pattern. Recently, real-time simulations of ice-structure interactions are gaining increasing traction due to their great application potential. The analytical or semi-analytical models implemented into the real-time simulator significantly influence the accuracy of real-time simulations. Against this backdrop, the cracking pattern assumption needs to be more critically examined, and the criterion for cracking pattern determinations is in demand for utilizing different models for different cracking patterns in real-time simulations. Motivated by this need, the current paper establishes the cracking pattern determination criterion for indented ice sheet bending failures, based on the theory of plates on elastic foundations and normalized formulae. It is found that large indentation lengths and radii of structure waterline curvature induce a circumferential-before-radial cracking pattern. Conversely, small indentation lengths and radii of structure waterline curvature result in a radial-before-circumferential cracking pattern.

Ice Load Calculation on Semi-Submersible Platform

2017 ◽  
Author(s):  
Marc Cahay ◽  
Brian A. Roberts ◽  
Sami Sadouni ◽  
Pierre-Antoine Béal ◽  
Cyril Septseault ◽  
...  
Keyword(s):  
Complex Geometry ◽  
Vertical Wall ◽  
Ice Sheet ◽  
Development Program ◽  
Offshore Structures ◽  
User Input ◽  
Sheet Bending ◽  
Common Framework ◽  
Multi Agent ◽  
Bending Failure

In 2012 TechnipFMC, Cervval and Bureau Veritas initiated a common development program to offer a new tool for the design of offshore structures interacting with ice combining a variety of models and approaches. This numerical tool called Ice-MAS (www.ice-mas.com) is using a multi-agent technology and has the possibility to combine in a common framework multiple phenomena from various natures and heterogeneous scales (i.e. drag, friction, ice-sheet bending failure, local crushing and rubble stack up). It can simulate the ice loadings of a drifting ice-sheet (including ridge or not) on predefined structures such as conical, cylindrical, sloping & vertical wall, artificial islands or more complex geometry by user input file like semi-submersible floaters with pontoon and columns allowing to obtain the detailed results on the different parts of the structure. This paper presents the overall functionalities of Ice-MAS and the different possibilities to model a semi-submersible floater. It will focus on the results obtained for different geometries subject to ice sheet loading through different incidence angles. The issues related to the anchoring of the platform are addressed in a simplified way.

scholarly journals ATCO radar training assessment and flight efficiency: the correlation between trainees’ scores and fuel consumption in real-time simulations

2020 ◽  
pp. 1-17
Author(s):  
T. Rogošić ◽  
B. Juričić ◽  
F. Aybek Çetek ◽  
Z. Kaplan
Keyword(s):  
Real Time ◽  
Fuel Consumption ◽  
Basic Training ◽  
Air Traffic Controller ◽  
Training Assessment ◽  
Assessment Scores ◽  
Human In The Loop ◽  
Assessment Standards ◽  
Two Parameters ◽  
Real Time Simulations

ABSTRACT Air traffic controller training is highly regulated but lacks prescribed common assessment criteria and methods to evaluate trainees at the level of basic training and consideration of how trainees in fluence flight efficiency. We investigated whether there is a correlation between two parameters, viz. the trainees’ assessment score and fuel consumption, obtained and calculated after real-time human-in-the-loop radar simulations within the ATCOSIMA project. Although basic training assessment standards emphasise safety indicators, it was expected that trainees with higher assessment scores would achieve better flight efficiency, i.e. less fuel consumption. However, the results showed that trainees’ assessment scores and fuel consumption did not correlate in the expected way, leading to several conclusions.

Wave Impact Loads on the Bottom of Flat Decks

2021 ◽  
Author(s):  
Daniel de Oliveira Costa ◽  
Julia Araújo Perim ◽  
Bruno Guedes Camargo ◽  
Joel Sena Sales Junior ◽  
Antonio Carlos Fernandes ◽  
...  
Keyword(s):  
Scale Effects ◽  
Offshore Structures ◽  
Model Tests ◽  
Analytical Models ◽  
Navier Stokes ◽  
Impact Loads ◽  
Wave Impact ◽  
Wave Channel ◽  
Waves And Currents ◽  
The Impact

Abstract Slamming events due to wave impact on the underside of decks might lead to severe and potentially harmful local and/or global loads in offshore structures. The strong nonlinearities during the impact require a robust method for accessing the loads and hinder the use of analytical models. The use of computation fluid dynamics (CFD) is an interesting alternative to estimate the impact loads, but validation through experimental data is still essential. The present work focuses on a flat-bottomed model fixed over the mean free surface level submitted to regular incoming waves. The proposal is to reproduce previous studies through CFD and model tests in a different reduced scale to provide extra validation and to identify possible non-potential scale effects such as air compressibility. Numerical simulations are performed in both experiments’ scales. The numerical analysis is performed with a marine dedicated flow solver, FINE™/Marine from NUMECA, which features an unsteady Reynolds-averaged Navier-Stokes (URANS) solver and a finite volume method to build spatial discretization. The multiphase flow is represented through the Volume of Fluid (VOF) method for incompressible and nonmiscible fluids. The new model tests were performed at the wave channel of the Laboratory of Waves and Currents (LOC/COPPE – UFRJ), at the Federal University of Rio de Janeiro.

scholarly journals Light-assisted electrospinning monitoring for soft polymeric nanofibers

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Dario Lunni ◽  
Goffredo Giordano ◽  
Francesca Pignatelli ◽  
Carlo Filippeschi ◽  
Stefano Linari ◽  
...  
Keyword(s):  
Real Time ◽  
Electrospun Fiber ◽  
Correlation Coefficients ◽  
Experimental Tests ◽  
Electrospinning Process ◽  
Analytical Models ◽  
Diameter Distribution ◽  
Soft Systems ◽  
Light Coupling ◽  
Waveguide Length

Abstract A real-time tool to monitor the electrospinning process is fundamental to improve the reproducibility and quality of the resulting nanofibers. Hereby, a novel optical system integrated through coaxial needle is proposed as monitoring tool for electrospinning process. An optical fiber (OF) is inserted in the inner needle, while the external needle is used to feed the polymeric solution (PEO/water) drawn by the process. The light exiting the OF passes through the solution drop at the needle tip and gets coupled to the electrospun fiber (EF) while travelling towards the nanofibers collector. Numerical and analytical models were developed to assess the feasibility and robustness of the light coupling. Experimental tests demonstrated the influence of the process parameters on the EF waveguide properties, in terms of waveguide length (L), and on the nanofibers diameter distribution, in terms of mean $$\widehat{D}$$ D ^ and normalized standard deviation $$\chi$$ χ . Data analysis reveals good correlation between L and $$\widehat{D}, \chi$$ D ^ , χ (respectively maximum correlation coefficients of $${\rho }_{L,\widehat{D}}$$ ρ L , D ^ = 0.88 and $${\rho }_{L,\chi }$$ ρ L , χ = 0.84), demonstrating the potential for effectively using the proposed light-assisted technology as real-time visual feedback on the process. The developed system can provide an interesting option for monitoring industrial electrospinning systems using multi- or moving needles with impact in the scaling-up of innovative nanofibers for soft systems.

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