Effect of Grain Size on the Internal Fracturing of Polycrystalline Ice
This work presents the results of a study to examine the effects of grain size of internal microfractures in polycrystalline ice. Laboratory-prepared specimens were tested under uniaxial, constant-load creep conditions at -5 C. Grain size ranged from 1.5 to 6.0 mm. This range of grain size, under an...
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ftdtic:ADA171571 2023-05-15T16:37:32+02:00 Effect of Grain Size on the Internal Fracturing of Polycrystalline Ice Cole,David M COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH 1986-07 text/html http://www.dtic.mil/docs/citations/ADA171571 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA171571 en eng http://www.dtic.mil/docs/citations/ADA171571 APPROVED FOR PUBLIC RELEASE DTIC AND NTIS Snow Ice and Permafrost Solid State Physics *GRAIN SIZE *ICE FRACTURE(MECHANICS) DUCTILE BRITTLE TRANSITION POLYCRYSTALLINE *Polycrystalline ice PE62730A AST42 WU004 Text 1986 ftdtic 2016-02-21T02:19:11Z This work presents the results of a study to examine the effects of grain size of internal microfractures in polycrystalline ice. Laboratory-prepared specimens were tested under uniaxial, constant-load creep conditions at -5 C. Grain size ranged from 1.5 to 6.0 mm. This range of grain size, under an initial creep stress of 2.0 MPa, led to a significant change in the character of deformation. The finest-grained material displayed no internal cracking and typically experienced strains of 10 to the minus 2nd power at the minimum creep rate epsilon. The coarse-grained material experienced severe cracking and a drop in the strain at epsilon min to approximately 4x10 to the minus 3rd power. Extensive post-test optical analysis allowed estimation of the size distribution and number of microcracks in the tested material. These data led to the development of a relationship between the average crack size and the average grain size. Additionally, the crack size distribution, when normalized to the grain diameter, was very similar for all specimens tested. The results indicate that the average crack size is approximately one-half the average grain diameter over the stated grain size range. A dislocation pileup model is found to adequately predict the onset of internal cracking. The work employed acoustic emission techniques to monitor the fracturing rate occurred. Other topics covered in this report include creep behavior, crack healing, the effect of stress level on fracture size and the orientation of cracked grains. Theoretical aspects of the grain size effect on material behavior are also given. Text Ice permafrost Defense Technical Information Center: DTIC Technical Reports database |
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Open Polar |
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Defense Technical Information Center: DTIC Technical Reports database |
op_collection_id |
ftdtic |
language |
English |
topic |
Snow Ice and Permafrost Solid State Physics *GRAIN SIZE *ICE FRACTURE(MECHANICS) DUCTILE BRITTLE TRANSITION POLYCRYSTALLINE *Polycrystalline ice PE62730A AST42 WU004 |
spellingShingle |
Snow Ice and Permafrost Solid State Physics *GRAIN SIZE *ICE FRACTURE(MECHANICS) DUCTILE BRITTLE TRANSITION POLYCRYSTALLINE *Polycrystalline ice PE62730A AST42 WU004 Cole,David M Effect of Grain Size on the Internal Fracturing of Polycrystalline Ice |
topic_facet |
Snow Ice and Permafrost Solid State Physics *GRAIN SIZE *ICE FRACTURE(MECHANICS) DUCTILE BRITTLE TRANSITION POLYCRYSTALLINE *Polycrystalline ice PE62730A AST42 WU004 |
description |
This work presents the results of a study to examine the effects of grain size of internal microfractures in polycrystalline ice. Laboratory-prepared specimens were tested under uniaxial, constant-load creep conditions at -5 C. Grain size ranged from 1.5 to 6.0 mm. This range of grain size, under an initial creep stress of 2.0 MPa, led to a significant change in the character of deformation. The finest-grained material displayed no internal cracking and typically experienced strains of 10 to the minus 2nd power at the minimum creep rate epsilon. The coarse-grained material experienced severe cracking and a drop in the strain at epsilon min to approximately 4x10 to the minus 3rd power. Extensive post-test optical analysis allowed estimation of the size distribution and number of microcracks in the tested material. These data led to the development of a relationship between the average crack size and the average grain size. Additionally, the crack size distribution, when normalized to the grain diameter, was very similar for all specimens tested. The results indicate that the average crack size is approximately one-half the average grain diameter over the stated grain size range. A dislocation pileup model is found to adequately predict the onset of internal cracking. The work employed acoustic emission techniques to monitor the fracturing rate occurred. Other topics covered in this report include creep behavior, crack healing, the effect of stress level on fracture size and the orientation of cracked grains. Theoretical aspects of the grain size effect on material behavior are also given. |
author2 |
COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH |
format |
Text |
author |
Cole,David M |
author_facet |
Cole,David M |
author_sort |
Cole,David M |
title |
Effect of Grain Size on the Internal Fracturing of Polycrystalline Ice |
title_short |
Effect of Grain Size on the Internal Fracturing of Polycrystalline Ice |
title_full |
Effect of Grain Size on the Internal Fracturing of Polycrystalline Ice |
title_fullStr |
Effect of Grain Size on the Internal Fracturing of Polycrystalline Ice |
title_full_unstemmed |
Effect of Grain Size on the Internal Fracturing of Polycrystalline Ice |
title_sort |
effect of grain size on the internal fracturing of polycrystalline ice |
publishDate |
1986 |
url |
http://www.dtic.mil/docs/citations/ADA171571 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA171571 |
genre |
Ice permafrost |
genre_facet |
Ice permafrost |
op_source |
DTIC AND NTIS |
op_relation |
http://www.dtic.mil/docs/citations/ADA171571 |
op_rights |
APPROVED FOR PUBLIC RELEASE |
_version_ |
1766027831830118400 |