Adult ; Gamma Rays ; Humans ; Male ; Radiation Protection ; instrumentation ; Space Suits

AIMTo observe the protection effect of a new combined anti-G measure which was composed of KH-x anti-G suit, unassisted PBG (positive pressure breathing for G, PBG) and PHP maneuver. The problem of fatigue and pain when using this measure was also discussed.

METHODSFive fully qualified centrifuge subjects were exposed to 5 groups of +Gz exposure: (1) relaxed tolerance, (2) KH-x and KT-x, (3) PBG, (4) 6.5 G 45 s, (5) 9.0 G 15 s. The subjective feeling of fatigue and pain induced by +Gz exposure was evaluated by the questionnaire after runs.

RESULTSThere was no incidents of G-induced lose of consciousness in this study. The protective effect of KH-x and KT-x was 2.3 G while it was 1.7 G for PBG. All the subjects have accomplished the 4th and 5th runs. The pain has developed on neck, waist, arm and hands. The problem of waist pain was very significant.

CONCLUSIONThe new combined anti-G measure could meet the requirement of +9.0 Gz protection for high performance plane. How to prevent the occurrence of neck injury and alleviate the pain induced by G when using this measure should be studied further.

Acceleration ; Adult ; Aerospace Medicine ; Fatigue ; prevention & control ; Gravity Suits ; Humans ; Male ; Pain ; prevention & control ; Space Suits ; Young Adult

The hand strength of astronauts, when they are outside the space capsule, is highly influenced by the residual pressure (the pressure difference between inside pressure and outside one of the suit) of extravehicular activity spacesuit glove and the pressure exerted by braided fabric. The hand strength decreases significantly on extravehicular activity, severely reducing the operation efficiency. To measure mechanical influence caused by spacesuit glove on muscle-tendon and joints, the present paper analyzes the movement anatomy and biomechanical characteristics of gripping, and then proposes a grip model. With phalangeal joint simplified as hinges, seven muscles as a finger grip energy unit, the Hill muscle model was used to compute the effects. We also used ANSYS in this study to establish a 3-D finite element model of an index finger which included both bones and muscles with glove, and then we verified the model. This model was applied to calculate the muscle stress in various situations of bare hands or hands wearing gloves in three different sizes. The results showed that in order to achieve normal grip strength with the influence caused by superfluous press, the finger's muscle stress should be increased to 5.4 times of that in normal situation, with most of the finger grip strength used to overcome the influence of superfluous pressure. When the gap between the finger surface and the glove is smaller, the mechanical influence which superfluous press made will decrease. The results would provide a theoretical basis for the design of the EVA Glove.
Astronauts ; Fingers ; physiology ; Finite Element Analysis ; Gloves, Protective ; adverse effects ; Hand Strength ; physiology ; Humans ; Mechanical Phenomena ; Pressure ; Space Suits ; adverse effects