Shape memory epoxy foams were used for an experiment aboard the International Space Station (ISS) to evaluate the feasibility of their use for building light actuators and expandable/deployable structures. The experiment named I-FOAM was performed by an autonomous device contained in the BIOKON container (by Kayser Italia) which was in turn composed of control and heating system, battery pack and data acquisition system. To simulate the actuation of simple devices in micro-gravity conditions, three different configurations (compression, bending and torsion) were chosen during the memory step of the foams so as to produce their recovery on ISS. Micro-gravity does not affect the ability of the foams to recover their shape but it poses limits for the heating system design because of the difference in heat transfer on Earth and in orbit. A recovery about 70% was measured at a temperature of 110 °C for the bending and torsion configuration whereas poor recovery was observed for the compression case. Thanks to these results, a new experiment has been developed for a future mission by the same device: for the first time a shape memory composite will be recovered, and the actuation load during time will be measured during the recovery of an epoxy foam sample.
Research Containing: Compression
Shape memory epoxy foams are a new class of materials for aerospace applications as light actuators, structural parts with reduced size during transport, and expandable/deployable structures. They were tested in an experiment onboard of the International Space Station in May 2011 (Shuttle Mission STS 134) and in April 2013, on board the BION-M1 capsule through the Soyuz-2 launch vehicle, with the aim to study the behavior in microgravity for future applications. The experiments were performed by an autonomous device which was in turn composed of control and heating system, battery pack and data acquisition system. Micro-gravity does not affect the ability of the foams to recover their shape but it poses limits for the heating system design because of the difference in heat transfer on earth and on orbit. This could be very significant for the behaviour of complex multi-functional structures in which shape memory epoxy foams are integrated. In this work, the main results of the experiments in microgravity are discussed and some results of tests on ground are shown in order to evaluate new possible developments in the field.
Mechanical forces, including gravity, tension, compression, hydrostatic pressure, and fluid shear stress, play a vital role in human physiology and pathology. They particularly influence extracellular matrix (ECM) gene expression, ECM protein synthesis, and production of inflammatory mediators of many load-sensitive adult cells such as fibroblasts, chondrocytes, smooth muscle cells, and endothelial cells. Furthermore, the mechanical forces generated by cells themselves, known as cell traction forces (CTFs), also influence many biological processes such as wound healing, angiogenesis, and metastasis. Thus, the quantitative characterization of CTFs by qualities such as magnitude and distribution is useful for understanding physiological and pathological events at the tissue and organ levels. Recently, the effects of mechanical loads on embryonic and adult stem cells in terms of self-renewal, differentiation, and matrix protein expression have been investigated. While it seems certain that mechanical loads applied to stem cells regulate their self-renewal and induce controlled cell lineage differentiation, the detailed molecular signaling mechanisms responsible for these mechano-effects remain to be elucidated. Challenges in the fields of both adult- and stem-cell mechanobiology include devising novel experimental and theoretical methodologies to examine mechano-responses more closely to various forms of mechanical forces and mechanotransduction mechanisms of these cells in a more physiologically accurate setting. Such novel methodologies will lead to better understanding of various pathological diseases, their management, and translational applications in the ever expanding field of tissue engineering.
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