On the deformation of human skin for mechanical counter pressure space suit development

Abstract

Exploration of planetary bodies requires space suits that do not inhibit astronaut mobility. Gas pressurized suits are typically bulky and stiff to operate or require unnatural human motion. Development of mechanical counter pressure (MCP) space suits can change the current space suit design paradigm. The primary goal of this thesis is to develop methodology to quantify strain and deformation of human skin to inform how to make a MCP space suit, or second skin, that maximizes mobility and minimizes human energy expenditure. Specific emphasis was placed on joint mobility, therefore, the Lines of Non-Extension (LoNE) was investigated in detail throughout the deformation of the human elbow joint. This goal was driven by three research objectives: develop a system to measure human skin deformation and strain, develop a rigorous method to compute LoNE, and examine the variation of skin strain between multiple subjects. The contributions of this thesis are the development of a multi-camera system to measure skin deformation at 1 mm², a streamline approach for calculating LoNE, strain data at the elbow joint and a methodology moving forward to measure more sections of the human body. The results from the six subjects showed that skin deformation can be similar in magnitude between subjects of varying anthropometrics, but the principal strain directions and LoNE maps can vary. The elbow data was flattened to 2D and normalized by anthropometrics to allow comparisons between subjects. This skin deformation data informs material selection, material placement, and suit patterning. This data is relevant to any compression garment or device that interacts with human skin.