Low-Temperature Flex Durability of Fabrics for Polar Sleds

• Main Authors: Lever, James H, Weale, Jason C, Durell, Glenn
• Format: Report
• Language: English
• Subjects: AIR PERMEABILITY TESTS; ANTARCTICA; ARCS MATERIALS; ARCS(AIR-RIDE CARGO SLEDS); Coatings, Colorants and Finishes; CRACKING(FRACTURING); DURABILITY; EPOLAR; FABRICS; FATIGUE CRACKS; FATIGUE(MECHANICS); FLEX-DURABILITY TESTS; FLEXIBILITY; FOLD-CRACKING PROBLEMS; FUEL-BLADDER MATERIALS; GELBO TEST; GREENLAND; HMW-PE(HIGH MOLECULAR WEIGHT POLYETHYLENE); LIGHTWEIGHT SLEDS; LOW TEMPERATURE; Mechanics; MOLECULAR WEIGHT; PERMEABILITY; PLASTIC COATINGS; Plastics; POLAR REGIONS; POLYETHYLENE PLASTICS; POLYMER-COATED FABRICS; SLEDS; STORAGE; Surface Transportation and Equipment; TENSILE CRACKING; TEST AND EVALUATION; Textiles

Lightweight fuel-bladder sleds are remarkably efficient and less expensive than conventional steel sleds for Antarctic resupply traverses. However, a significant fraction of fuel bladders develop cracks after being emptied and folded for return transport and storage. We conducted low-temperature flex-durability tests of existing and candidate bladder materials to understand the fold-cracking problems and to seek more durable materials. The fabric specimens underwent repeated cycles of severe twisting and folding at -40 C, after which the specimens were checked for leaks by using an air-permeability test. Remarkably, the existing bladder material could withstand hundreds of cycles before cracking and leaking, and it performed better than tested alternatives. We speculate that months-long folded storage of bladders causes stress-relaxation in the polymer coating at tight folds, and pre-season unfolding then induces tensile cracking. In 2013, the South Pole Traverse (SPoT) acted on our recommendation to transport and store empty bladders inflated. They reported very promising results: no leaks in bladders and shorter preparation times for sled reuse. The flex-durability tests also identified very durable materials to build enclosure pouches for air-ride cargo sleds (ARCS). ARCS have the potential to transport rigid and out-size cargo as efficiently as fuel in bladder sleds. The original document contains color images.