Nonsimultaneous Failure And Ice Loads On Arctic Structures

Ashby, MF; Palmer, AC; Thouless, M.; Goodman, D. J.; Howard, Michele; Hallam, S.D.; Murrell, Stanley A.; Jones, Norman; Sanderson, T. J. O.; Ponter, A. R. S.

doi:10.4043/5127-ms

Cited by 21 publications

(12 citation statements)

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“…The results of Ashby et al (1986) are shown in Fig. 2 along with the calculated penetration stress from the micromechanical model.…”

Section: Model Of Penetrationmentioning

confidence: 99%

“…The normal and frictional forces are given by The second force condition of interest occurs after the initial rupture of microstructural elements that produces a randomly distributed surface geometry of intact microstructural elements. In this situation, the deflection and force exerted on a penetrometer by any microstructural element in contact has an equal probability of taking any value between zero and fp,r' This condition is described by a uniform probability distribution with probability density function Ashby et al (1986) conducted a series of penetration tests in zirconia foam using a flat faced penetrometer/indenter. In these tests, the initial penetration stress increased to a peak then fell back to near zero.…”

Section: Model Of Penetrationmentioning

confidence: 99%

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Characterizing the microstructural and micromechanical properties of snow

Johnson

Schneebeli

1999

Cold Regions Science and Technology

104

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ABSTRACT:A micropenetrometer has been developed that produces snow grain bond ruptures at the microstructural level and provides a unique signal for different snow types . A micromechanical theory of penetration has been developed and used to recover microstructural and micromechanical parameters for different snow types from the penetration force-distance signal. These parameters are the microstructural element dimension, the mean grain size, the critical microstructural deflection at rupture and the microstructural coefficient of elastic restitution. Additional derived mechanical properties include the compression strength and elastic modulus of microstructural elements and continuum scale volumes of snow. Analysis of the forcedistance signal from a Monte Carlo simulation of micropenetration indicates that microstructural and micromechanical parameters may be recovered with an accuracy of better than 5% when spatial and force resolutions are high and the penetrometer tip area is of similar size to the structure dimension.

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“…The results of Ashby et al (1986) are shown in Fig. 2 along with the calculated penetration stress from the micromechanical model.…”

Section: Model Of Penetrationmentioning

confidence: 99%

Section: Model Of Penetrationmentioning

confidence: 99%

Characterizing the microstructural and micromechanical properties of snow

Johnson

Schneebeli

1999

Cold Regions Science and Technology

104

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“…As stated in the independent failure zone theory by Ashby et al [7], the interaction between an ice block of thickness h and a structure of width D is studied. The irregular contact area with dimension h × D is divided into a set of small zones with dimensions L i × L i , as shown in Figure 2.…”

Section: Non-simultaneous Ice Failure Modelmentioning

confidence: 99%

“…According to Palmer et al [5], fragments of crushed ice were found to have a fractal size distribution. Ashby et al [7] divided the whole contact area into N independent zones and estimate the total force across the contact area based on pressure in each failure zone. Ashby et al [7] divided the whole contact area into N independent zones and estimate the total force across the contact area based on pressure in each failure zone.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, a new analytical model on ice non-simultaneous failure that combines the independent failure zone theory of brittle materials [7] and a dynamic ice-structure interaction model [11,12] is developed. In this paper, a new analytical model on ice non-simultaneous failure that combines the independent failure zone theory of brittle materials [7] and a dynamic ice-structure interaction model [11,12] is developed.…”

Section: Introductionmentioning

confidence: 99%

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An Ice-Structure Interaction Model for Non-simultaneous Ice Failure

Karr

2014

All Days

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This paper presents a new analytical model to simulate time-dependent response of structures subjected to ice impact. The ice forces are limited by ice failure with the ice considered to fail in multiple zones non-simultaneously. The results of numerical simulation of structural response to the non-simultaneous ice failure loads are provided. Non-simultaneous ice failure is one important failure mode of larger scale ice moving at moderate to high speed. This model combines previous independent failure zone theory of brittle materials and a dynamic ice-structure interaction model.Developing offshore energy has become more and more serious worldwide in recent years with considerable offshore and shipping activities in the Arctic. Ice is a dominant feature of the Arctic region and predicting interaction effects on offshore structures and ships operating in the Arctic is essential in Arctic engineering. The ability to understand the magnitude and cyclic nature of ice forces and structure response is a key aspect for offshore structural design in cold regions. The prediction of structural response when encountering interactions with ice is essential for safe operations in this region. The model presented here is an effort to better understand and predict ice forces.This model is able to produce an ice load time history, which can be applied to dynamic ice-structure interaction analysis. The model can also generate a pressure-area curve based on the input ice characteristics. The resulting shape of the pressure-area curve is shown to depend upon input parameters. Besides the pressure area relationships, the resulting pressure dependence on various parameters is also studied such as independent zone size, shape and strength.

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Continuum cavity expansion and discrete micromechanical models for inferring macroscopic snow mechanical properties from cone penetration data

Ruiz

Capelli

Herwijnen³

et al. 2017

Geophysical Research Letters

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Digital cone penetration measurements can be used to infer snow mechanical properties, for instance, to study snow avalanche formation. The standard interpretation of these measurements is based on statistically inferred micromechanical interactions between snow microstructural elements and a well‐calibrated penetrating cone. We propose an alternative continuum model to derive the modulus of elasticity and yield strength of snow based on the widely used cavity expansion model in soils. We compare results from these approaches based on laboratory cone penetration measurements in snow samples of different densities and structural sizes. Results suggest that the micromechanical model underestimates the snow elastic modulus for dense samples by 2 orders of magnitude. By comparison with the cavity expansion‐based model, some of the discrepancy is attributed to low sensitivity of the micromechanical model to the snow elastic modulus. Reasons and implications of this discrepancy are discussed, and possibilities to enhance both methodologies are proposed.

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Nonsimultaneous Failure And Ice Loads On Arctic Structures

Cited by 21 publications

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Characterizing the microstructural and micromechanical properties of snow

Characterizing the microstructural and micromechanical properties of snow

An Ice-Structure Interaction Model for Non-simultaneous Ice Failure

Continuum cavity expansion and discrete micromechanical models for inferring macroscopic snow mechanical properties from cone penetration data

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