スーパープレッシャー気球用網の引張強度評価

抄録

Super-pressure balloons have been developed for scientific observation at high altitude. The strength of net that covers balloon's surface is important to utilize the balloon in safety. The purpose of this study is to evaluate the practicable condition by determining fracture strength and elastic modulus. Net of balloon have mesh of rope to cover the whole balloon. Polyarylate rope for our super-pressure balloon is formed by two strands which is consists of many thin fibers. Tensile test of a single fiber, a rope and a rope with a point of intersection were carried out. Rope is made of Polyarylate which is used for super-pressure balloons. The tensile strength of a single fiber is 80% of bulk specimen, and that of a rope is 45%. Following reasons are considered for the decrease of the strength; 1. a twisted rope has a torque which makes twist back force, 2. friction between piled fibers due to loading on piled fibers. Moreover, the strength of rope containing a point of intersection is 40% of bulk specimen. This is because friction is generated at a point of intersection where rope contact each other. Although the fracture strength of the Polyarylate rope is smaller than that of the bulk, it is well higher than that of the strength required for pressurized balloons. It is shown that the rope is practicable as a net of super-pressure balloons.