Low-Temperature Flex Durability of Fabrics for Polar Sleds

Abstract : 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.