One of the problems with exposure to microgravity is the shift of the blood centre towards the upper part of the body. This leads to a series of physiological changes that have a negative impact on the body, such as increased pressure in the skull and visual disturbances. The most promising countermeasure is the application of lower body negative pressure (LBNP), which expands the exposed tissues, causing the blood centre to shift back towards the lower body. To achieve positive effects, astronauts would need to be exposed to LBNP for a prolonged period of time, which is not possible with current rigid support solutions that separate the negative pressure from the surrounding environment. In this study, we investigate the effect of negative pressure on the soft tissue response and develop a numerical model of the lower body in the thigh region to analyse the effect of negative pressure. To determine the material properties of the model, we develop an inverse identification method based on recordings from a portable ultrasound device. The tissue response is analysed in relation to the developed wavy substructure, and the results are evaluated on the basis of the change in tissue volume induced by a given geometric variation of the support structure. The use of the latter is evaluated on the basis of contact pressures, which represent the limit of safe use.
|
