Courbe Intrinseque De La Glace en Compression

Nadreau, J.-P.; Michel, B.

doi:10.1051/jphyscol:1987145

Cited by 3 publications

(3 citation statements)

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“…It can be seen that these conditions depend on both the triaxial stress system (in particular the confining pressure and the tensile or compressive nature of the stresses) and the temperature and strain-rate (grain-size is also important, see Murrell, 1990). Few triaxial mechanical tests have been reported on ice, and the great majority have been limited to relatively high temperatures and relatively low strain-rates, under which conditions crystal plastic creep has been the dominant deformation mechanism (Jones, 1982;Nadreau and Michel, 1986;Richter-Menge et al, 1986;Cox and Richter-Menge, 1986). However, Durham et al, (1983) have studied the confined brittle fracture of pure ice at temperatures below 195K.…”

Section: Introductionmentioning

confidence: 97%

Strength and Failure Modes of Pure Ice and Multi-Year Sea Ice Under Triaxial Loading

Murrell

Sammonds

Rist

1991

Ice-Structure Interaction

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Following a brief description of a new servo-controlled triaxial testing system for large ice samples (ca. 40mm diameter) with facilities for acoustic emission (AE) observations, and of a technique for manufacturing pure ice samples, laboratory results are presented for the strength of ice under uniaxial tension, and under uniaxial and triaxial compression. Data has been gathered using strain rates up to 10-2 /s, confining pressures up to 30MPa and temperatures down to -40°C. The pure ice had a uniform grain size of about 1mm and a high density. The sea ice, collected from the Canadian High Arctic, had a large natural variability of structure, salinity and density. The test conditions straddle the boundary between brittle cracking and fracture behaviour, and high temperature plasticity. The behaviour shows some similarities with that of silicate rocks and covalent oxides. At low temperatures and high strain rates ice fracture exhibits a pressure dependence similar to that of brittle rocks, with strength increasing as confining pressure increases. AE is also similar to that of brittle rocks. However, at higher temperatures and pressures, where ductile behaviour occurs, increasing pressure leads to decreasing strength. The peak strengths observed during ductile behaviour are not yet fully understood. The results are discussed in terms of Griffith crack theory.

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Section: Introductionmentioning

confidence: 97%

Strength and Failure Modes of Pure Ice and Multi-Year Sea Ice Under Triaxial Loading

Murrell

Sammonds

Rist

1991

Ice-Structure Interaction

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“…by healing cracks and melting grains). A pressure of 110 MPa will cause melting at –10°C (Nadreau and Michel, 1987; Nordell, 1990). Since pressures of 70 MPa have been observed under field conditions (Frederking and others, 1990), and pressures on the order of 50 MPa are not uncommon, the effects of localized stress concentrations of these applied loads could be sufficient to initiate melting during ice–structure interaction at grain boundaries.…”

Section: Introductionmentioning

confidence: 99%

Microstructural change in ice: I. Constant-deformation-rate tests under triaxial stress conditions

et al. 1999

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Extensive damage to ice occurs during ice structure interaction by microcracking, recrystallization and melting. The objective of this work was to investigate this damage process under confined-stress conditions believed to be associated with impact zones that occur during ice–structure interaction. “Damage” refers to microstructural modification that causes deterioration of the mechanical properties. Prior experimental work has shown that a small amount of deformation causes permanent damage in ice, leading to enhanced creep rates during subsequent loading. To investigate this softening, freshwater granular ice was deformed under moderate confinement (20 MPa) at –10°C, at two rates which bracket ductile and brittle behavior (10−2 s−1 and 10−4 s−1). Samples were deformed to different levels of axial strain up to 28.8%. Thin sections were examined to assess the progressive changes in microstructure.Both grain-boundary and intra-granular cracking began at strains corresponding to the peak stress (1–2%) for tests at both strain rates. The peak stresses were 23.4 MPa for the tests at 10−2 s−1 and 9.8 MPa for the tests at 10−4 s−1. At strains of > 1–2%, dense clusters of intra-granular cracks began to develop in the samples tested at the higher rate. At the lower rate, dynamic recrystallization was apparently the dominant deformation mechanism beyond the peak stress. The average grain-size decreased strongly during the first few per cent strain and then maintained a relatively stable value.

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“…by healing crac ks a nd melting grai ns). A pressure of 110 MPa will cause melting at -lOoC (Nadreau and Michel, 1987;Nordell, 1990). Since pressures of 70 MPa have been observed under field conditions (Frederking and others, 1990), a nd press ures on the order of 50 MPa a re not uncommon, the effects of localized stress concentra ti ons of these appli ed load s could be sufficient to initi a te melting during ice-structure interac tion a t grain bound a ries.…”

Section: Daillage Illechanicsmentioning

confidence: 99%

Microstructural change in ice: I. Constant-deformation-rate tests under triaxial stress conditions

et al. 1999

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Extensive da mage to ice occ urs during ice-structure interac ti o n by microc racking, recrystalli zati o n a nd melting, Th e obj ecti ve of this wo rk was to investigate this da m a ge process unde r confin ed-stress conditi o ns beli eved to bc assoc ia ted with impact zo nes th a t occ ur durin g ice-structure inte r ac ti on, "Da m age" refers to mi c ros truc tura l mod ifi cati o n th at causes d e teriorati on o f the m ee ha nica l prope rti es, Prior exp erimental work h as shown that a sm a ll a mo unt of defo rm a ti on causes pe rm a nent da mage in ice, leading to e nh a nced creep ra tes during subsequc nt load ing, To investigate thi s soft ening, fr es hwater g ra nul a r ice was defo rmed under m od era te confineme nt (20 :'IiPa ) a t -10°C, a t two rates which brac ket duc ti le a nd brittl e beh avio r (10 2 s I a nd 10 + s I). Sa mples were deform ed to different level s of ax ial strain up to 28,8% , Thin sec tio ns we re exam i ned to assess the prog ressive cha nges in microstructure, Bo th g ra in-bound a ry a nd intra-g ra nul a r c rac king began a t strains co rrespond ing to th e peak stress (1-2% ) fo r tests at both stra in ra tes. The peak stresses we re 23.4 MPa for the tests a t 10 2 S I a nd 9.8 MPa for th e tes ts a t 10 + s I, At strains of > 1-2%, d e n se elusters of intra-g ra nul a r crac ks b ega n to develop in th e samples tes ted a t the highe r ra te, At th e lower ra te, d yna mic rec rys ta lli zati on was a ppa rently the do min a nt defo rm a ti o n m eeha nism b eyo nd the pea k stress. The a\' C rage g r a in-size decreased stro ngly during th e fi rst few per ce nt stra in a nd then m a intained a rela tivel y stabl e va lue.

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Courbe Intrinseque De La Glace en Compression

Cited by 3 publications

References 1 publication

Strength and Failure Modes of Pure Ice and Multi-Year Sea Ice Under Triaxial Loading

Strength and Failure Modes of Pure Ice and Multi-Year Sea Ice Under Triaxial Loading

Microstructural change in ice: I. Constant-deformation-rate tests under triaxial stress conditions

Microstructural change in ice: I. Constant-deformation-rate tests under triaxial stress conditions

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