关键词: 总八面体剪应变;最小应变率;晶粒c轴组构;组构平均半角

Abstract:

Uniaxial extension tests were performed until large amount of strain on six laboratory-prepared ice samples with initial randomly-oriented fine crystals at the temperature -3.0±0.05C° and the octahedral shear stress 0.2MPa and 0.3MPa. The minimum octahedral shear strain rate is 2.6x10 -8 s -1 for one test at octahedral shear stress 0.2MPa and the average 8.6x10 -8 s -1 for the other five at octahedral shear stress 0.3MPa and occurred at the total octahedral shear strain between 1% and 1.6% in all tests. With the increasing strain, the crystal c-axis orientation changes developing a large girdle fabric with mean half girdle angle around 65° at total octahedral shear strain approximately 60%. Beyond this, the mean half girdle angle tends to be steady. However, possibly due to the geometry of fabric diagram the mean half girdle angle deceases before 20% or so total octahedral shear strain. In comparison with the results from uniaxial compression tests, the minimum strain rate in extension agrees to that in compression at same temperature and stress, but the total strain is slightly greater at the minimum strain rate and much greater to develop the fabric.