PENETRATION STUDIES OF ICE WITH APPLICATION TO ARCTIC AND SUBARCTIC WARFARE - PHASE II STUDY

• Main Author: Ross, Bernard
• Other Authors: STANFORD RESEARCH INST MENLO PARK CA NAVAL WARFARE RESEARCH CENTER
• Format: Text
• Language: English
• Published: 1967
• Subjects: Snow; Ice and Permafrost; Ammunition and Explosives; *PROJECTILES; *ICE; MATHEMATICAL MODELS; TEMPERATURE; THICKNESS; IMPACT; GUN LAUNCHERS; TENSILE PROPERTIES; FRACTURE(MECHANICS); PENETRATION; CYLINDRICAL BODIES; CONFIGURATIONS; WEIGHT; AIR DROP OPERATIONS; LABORATORIES; HYDROPHONES; SALINITY; SEA RESCUES; CONICAL BODIES; ANTISUBMARINE WARFARE; DIGITAL COMPUTERS; BLUNT BODIES; SONOBUOYS; ARCTIC REGIONS; ARCTIC OCEAN; SNOW VEHICLES; VELOCITY; COMPUTER PROGRAMS; CORE SAMPLING; PERFORATION; Arctic; Arctic Ocean; Barrow; Ice; permafrost; Point Barrow; Sea ice; Subarctic; Alaska
• Online Access: http://www.dtic.mil/docs/citations/AD0817598; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0817598

Impact tests with freely falling and explosively powered projectiles were performed on laboratory sea ice test slabs made from frozen seawater at Stanford Research Institute, and on Arctic sea ice in situ at Point Barrow, Alaska. In the experiments, particular attention was devoted to studying the mechanisms of penetration and perforation. Ranges of values investigated for the basic parameters were: impact velocity, 8-20 ft/sec and 50-494 ft/sec; projectile weights, 0.75, 9.69, and 41.5 lb; penetrator diameters, 5/8 in., 1-1/ 4 in., and 6 in.; penetrator profiles, blunt and conical; sea ice thickness, 3- 3/8 - 17 in.; sea ice temperature, +7F - +32F, and sea ice salinity, 7.2 - 17.1 ppm. All tests were carried out at normal incidence except for one sequence on Arctic sea ice in which the angle of incidence was 17.3 degrees from vertical. Results of the tests indicate that a cylindrical, blunt-end penetrator was more effective in perforation than a corresponding penetrator with a conical end. The blunt penetrator, impacting at normal incidence, perforated both laboratory sea ice and Arctic sea ice by expelling a cylindrical-conical shear plug from the test specimen. For this behavior, a mathematical model was constructed and a theoretical analysis developed from which the minimum impact velocity for perforation (critical velocity) was obtained. The critical velocity was found to be a function of projectile mass and diameter, and sea ice thickness, shear strength, tensile strength, and elastic modulus. The theory did not consider effects due to cratering.