Investigation of the Interaction Between a Human Index Finger and Spacesuit Glove

Abstract

With over five decades of spaceflight experience, from the Mercury Program to the current International Space Station, it is well recognized that Extravehicular Activity (EVA), is a critical operational capability necessary for successful space habitation. Whether in LEO or on the Lu-nar and Martian surfaces, an EVA suit must provide life support systems, communication, power, thermal protection and radiation protection. In addition to these functions, the EVA suit must be comfortable and not inhibit the performance of the human. A critical component of the EVA suit are the gloves. Whether it be for exterior assembly, maintenance or science-based surface operations, there will be a continued reliance on manual tasks, requiring fine use of a crew member’s hands. The long duration nature of a Lunar or Martian mission requires spacesuit gloves to be reliable, durable and nearly invisible to the crew-member. While several researchers have studied the effects of EVA Gloves and pressurization on hand strength, dexterity and tactility, these efforts relied on exterior measures of the performance of a glove. Although measures such as grip strength, range of motion and task completion time are valid metrics for how well a glove per-forms, they provide little insight on the mechanics of the human-glove interaction. To engineer the best glove for future LEO, Lunar and Martian EVA missions, it is critical to develop a deeper understanding of the complex interactions that take place inside of the glove. A finite element model of the interaction between the human index finger and notional EVA glove pressure bladder and restraint layer was developed to further understand this interaction. It was found that material modulus was the largest contributing factor (accounting for approximately 72% of overall stiff-ness) followed by bunching of the glove (accounting for approximately 25% of overall stiffness). It was also determined that pressure had minimal effect on the overall stiffness of the EVA glove finger. Additionally it was found that the pre-bunching of the restraint layer significantly reduced the overall stiffness of the glove finger. Finally, it was shown that material modulus and thickness of the restraint layer, material thickness of the pressure bladder and convolute size had the largest effects on glove stiffness.