Estimation of Local Ice Pressure Using Up-Crossing Rate

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Chuanke Li ◽  
Ian J. Jordaan ◽  
Rocky S. Taylor
Keyword(s):  
Probabilistic Method ◽  
Companion Paper ◽  
Offshore Structures ◽  
Maximum Pressure ◽  
Local Pressure ◽  
Data Set ◽  
Pressure Area ◽  
Rate Method ◽  
Ice Pressure ◽  
Maximum Method

Ice load estimation is required in the design of ships and offshore structures for arctic and subarctic conditions. This paper focuses on the estimation of local ice pressures. The “event-maximum” method for local ice pressure analysis is a probabilistic method based on the maximum pressure of a given event; other local peaks in the data are not included. To study how this may affect local ice pressure estimates, a new probabilistic method based on the up-crossing rate was developed. Field data from 1982 Polar Sea arctic trials in the Beaufort Sea are processed as a time series. Up-crossing rates at different local pressure levels are obtained for local areas of interest. A relationship between up-crossing rate and local pressure-area results is established. Results from the analysis of full-scale data using the event-maximum method are presented for the selected data set; a more comprehensive set of results for the analysis of available ship-ice interaction data is presented in a companion paper. For a sample case, local ice pressure estimates obtained using the up-crossing rate method are compared with results obtained using the event-maximum method. The local pressure-area relationship is found to be similar for both the up-crossing rate method and the event-maximum method. For design curves based on the data set considered, estimates using the event-maximum method were more conservative than those obtained using the up-crossing rate method. The up-crossing rate approach is promising; analysis of additional data sets is recommended to allow broader comparison of the methods.

Estimation of Local Ice Pressure Using Up-Crossing Rate

2009 ◽  
Author(s):  
Chuanke Li ◽  
Ian J. Jordaan ◽  
Rocky S. Taylor
Keyword(s):  
Companion Paper ◽  
Offshore Structures ◽  
Maximum Pressure ◽  
Local Pressure ◽  
Pressure Area ◽  
Arctic Conditions ◽  
Rate Method ◽  
Ice Pressure ◽  
Areas Of Interest ◽  
Maximum Method

Ice load estimation is required for offshore structures designed for arctic and sub-arctic conditions. This paper focuses on the estimation of local ice pressures. The ‘event-maximum’ method for local ice pressure analysis is based on the maximum pressure of a given event; other local peaks in the data are not included. To study how this may affect local ice pressure estimates, a method based on the up-crossing rate was developed. Field data from 1982 Polar Sea arctic trials in the Beaufort Sea are processed as a time series. Up-crossing rates at different local pressure levels are obtained for local areas of interest. A relationship between up-crossing rate and local pressure-area results is established. Results from the analysis of full-scale data using the event-maximum method are presented in a companion paper. For a sample case, local ice pressure estimates obtained using the up-crossing rate method are compared with those presented in the companion paper, based on analysis using the event-maximum method. The local pressure-area relationship is found to be similar for both the up-crossing rate method and the event-maximum method. Both methods and corresponding analysis results are compared.

Local Design Pressures for Structures in Ice: Analysis of Full-Scale Data

2009 ◽  
Author(s):  
Rocky S. Taylor ◽  
Ian J. Jordaan ◽  
Chuanke Li ◽  
Denise Sudom
Keyword(s):  
Companion Paper ◽  
Full Scale ◽  
Local Pressure ◽  
Event Duration ◽  
Alternative Approach ◽  
Ice Conditions ◽  
Two Parameters ◽  
Source Of Information ◽  
Maximum Method ◽  
Pressure Analysis

The design of structures for ice conditions requires knowledge of local ice pressures to allow for appropriate levels of structural strengthening. Full-scale field data are key to enhancing our understanding and modeling of ice behavior. Data collected during icebreaker ramming events represent an important source of information for use in the evaluation and validation of design methodologies. This paper examines several ship-ice interaction datasets using the ‘event-maximum’ method of local pressure analysis developed by Jordaan and co-workers [1]. In this method, the local pressure is obtained from a normalized curve which contains two parameters, α and x0. Local pressure analysis results for data from the USCGS Polar Sea, CCGS Terry Fox, CCGS Louis St. Laurent, and Swedish Icebreaker Oden are presented. For all data considered the calculated values of α fall below the design curve. A discussion of panel exposure, event duration and the effect of these factors on x0 is given. New design curves are presented. A comparison of results with those obtained using an alternative approach, the up-crossing rate method, is presented in a companion paper [2].

Reanalysis of Ice Pressure-Area Relationships

2007 ◽  
Vol 44 (04) ◽  
pp. 234-244
Author(s):  
C. G. Daley
Keyword(s):  
Contact Area ◽  
Offshore Structures ◽  
Polar Regions ◽  
General Description ◽  
Average Pressure ◽  
Pressure Data ◽  
The World ◽  
Pressure Area ◽  
Ice Loads ◽  
Ice Pressure

In the polar regions of the world, ships and offshore structures may be subject to impacts with large ice features. Pressure-area models are commonly used to determine both local and global ice loads. A general description of the two types of ice pressure-area models is given. Reanalysis of data from the trials on the USCGC Polar Sea suggests rising average pressure with rising contact area, quite the opposite of the expected result. A quick review of other ice pressure data lends support to the hypothesis. The paper concludes with a discussion of the implications and needed research to improve our understanding of ice loads.

A Novel Data Processing Method for Ice Pressure Area Relations

2014 ◽  
Author(s):  
Karoline M. Neumann ◽  
Sören Ehlers ◽  
Bernt J. Leira
Keyword(s):  
Data Processing ◽  
Processing Method ◽  
Point Of View ◽  
Sensing Matrix ◽  
Data Set ◽  
Data Processing Method ◽  
Pressure Area ◽  
Novel Processing ◽  
Temporal Events ◽  
Ice Pressure

An ice pressure data processing method based on definitions of basic, spatial and temporal events is described. The data processing method can be applied on a data set of semi continuous ice structure interaction observed with a finely meshed pressure sensing matrix with high sampling rates. An available data set satisfying these conditions from a model scale experiment in the Aalto ice tank is used to illustrate the application of the method. Using this novel processing method, each sample is associated with defined events, making it simple to produce various curves from the data set. Global and local, as well as spatial and process representations of pressure area curves are discussed, from design and ice research point of view. Finally four different pressure area curves are presented based on the application of the described processing method on the example data set. This processing methods aims to make extraction of results simpler for the designer and the scientist.

A revised ice pressure-area curve and a fracture mechanics explanation

2009 ◽  
Vol 56 (2-3) ◽  
pp. 73-76 ◽  
Author(s):  
A.C. Palmer ◽  
J.P. Dempsey ◽  
D.M. Masterson
Keyword(s):  
Fracture Mechanics ◽  
Pressure Area ◽  
Ice Pressure

scholarly journals ACAT1 Benchmark of RANS-Informed Analytical Methods for Fan Broadband Noise Prediction—Part I—Influence of the RANS Simulation

Acoustics ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 539-578
Author(s):  
Carolin Kissner ◽  
Sébastien Guérin ◽  
Pascal Seeler ◽  
Mattias Billson ◽  
Paruchuri Chaitanya ◽  
...  
Keyword(s):  
Turbulence Model ◽  
Analytical Methods ◽  
Companion Paper ◽  
Broadband Noise ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Data Set ◽  
The Past ◽  
Flow Turbulence ◽  
Diverse Data

A benchmark of Reynolds-Averaged Navier-Stokes (RANS)-informed analytical methods, which are attractive for predicting fan broadband noise, was conducted within the framework of the European project TurboNoiseBB. This paper discusses the first part of the benchmark, which investigates the influence of the RANS inputs. Its companion paper focuses on the influence of the applied acoustic models on predicted fan broadband noise levels. While similar benchmarking activities were conducted in the past, this benchmark is unique due to its large and diverse data set involving members from more than ten institutions. In this work, the authors analyze RANS solutions performed at approach conditions for the ACAT1 fan. The RANS solutions were obtained using different CFD codes, mesh resolutions, and computational settings. The flow, turbulence, and resulting fan broadband noise predictions are analyzed to pinpoint critical influencing parameters related to the RANS inputs. Experimental data are used for comparison. It is shown that when turbomachinery experts perform RANS simulations using the same geometry and the same operating conditions, the most crucial choices in terms of predicted fan broadband noise are the type of turbulence model and applied turbulence model extensions. Chosen mesh resolutions, CFD solvers, and other computational settings are less critical.

Development of a Probabilistic Ice Load Model Based on Empirical Descriptions of High Pressure Zone Attributes

2014 ◽  
Author(s):  
Rocky S. Taylor ◽  
Martin Richard
Keyword(s):  
High Pressure ◽  
Failure Process ◽  
Temporal Distribution ◽  
Tactile Sensor ◽  
Companion Paper ◽  
Offshore Structures ◽  
Load Model ◽  
Ice Load ◽  
High Pressure Zone ◽  
Ice Failure

During an ice-structure interaction, the localization of contact into high pressure zones (hpzs) has important implications for the manner in which loads are transmitted to the structure. In a companion paper, new methods for extracting empirical descriptions of the attributes of individual hpzs from tactile sensor field data for thin first-year sea ice have been presented. In the present paper these new empirical hpz relationships have been incorporated into a probabilistic ice load model, which has been used to simulate ice loads during level ice interactions with a rigid structure. Additional aspects of the ice failure process, such as relationships between individual hpzs and the spatial-temporal distribution of hpzs during an interaction have also been explored. Preliminary results from the empirical hpz ice load model have been compared with existing empirical models and are discussed in the context of both local and global loads acting on offshore structures.

Variations of the Local Failure Pressure With Depth Through First-Year and Multi-Year Ice

1988 ◽  
Vol 110 (2) ◽  
pp. 159-168 ◽  
Author(s):  
D. Blanchet
Keyword(s):  
Ice Thickness ◽  
First Year ◽  
Strain Rates ◽  
Failure Pressure ◽  
Pressure Profiles ◽  
Vertical Distributions ◽  
Pressure Area ◽  
Ice Floes ◽  
Ice Pressure ◽  
The Vertical Distribution

Typical vertical distributions of the failure pressure in an ice sheet are presented. The distributions, derived for intermediate strain rates, are a function of many parameters, namely, the salinity, the temperature, the type of ice, the location of the ice pressure area through the ice thickness, the thickness of ice, the density, and the crack and flaw distributions. Two combinations of these parameters lead to “representative” summer and winter vertical ice pressure profiles for 8 and 2-m thick ice floes. The importance of the vertical distribution of the failure pressure inside an ice cover is fundamental for two reasons. The change in the eccentricity of the resultant of the load induces changes in failure mode and load transmission to the structure. This nonuniform distribution will create nonsimultaneous failure and the ice pressure on the structure will not be hydrostatically distributed over a given area.

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