Characterization of particulate in vacuum casting for long term space flight.

摘要

Introduction: NASA has expressed a need for a new method of treating upper extremity fractures on long range exploration missions. Currently, fiberglass casts are the gold standard for fracture treatment on Earth, but there is little to no research into alternative methods to treat/secure more serious fractures on long range. For this study vacuum sealed particulate was considered as a possible casting material. The aim of this study was to identify candidate particulates and quantify their stabilization effectiveness, create designs that incorporated the vacuum sealed particulate, and test therapeutic ultrasound's ability to penetrate the material.;Materials and Methods: Samples were made that contained four different potential cast materials: ground coffee, sawdust, green clay powder and bentonite clay powder. Three point bending was conducted on the sample groups using an Instron to gather load/displacement. Control samples made of standard fiberglass were also tested. The design chosen to house the particulate was a wrap. The wrap was sectioned off into a four and eight well design and tested in three point bending. Piezo-electric transducers were used to output an ultrasound pulse through samples of varying thicknesses. The transducers were connected to an oscilloscope to show the amount to signal able to pass through the samples. Amplitude of each signal was measured and compared to a control (piezo-electric discs touching in water).;Results: Elastic moduli of the four materials were compared and we saw that the coffee consistently showed a higher elastic modulus throughout testing. For this reason, along with other material properties found in literature, we concluded that coffee was the most fitting cast particulate out of the four materials. The load/displacement data for the wrap design was represented graphically and correlations were found between the stiffness of the layered wrap designs and the stiffness of thicker samples. For the ultrasound testing it was found that the ultrasound waves were not able to effectively penetrate the particulate layers. Discussion and.;Conclusion: Development of a new and effective casting technique will increase the safety of astronauts as NASA expands their program to include long range space missions. This study shows the material properties of the particulates as well as the potential effectiveness of a vacuum sealed cast.