A -- Nastic Structures (NAST) Workshop

Nastic Structures (NAST) Workshop, SN03-19. The Defense Sciences Office (DSO) of the Defense Advanced Research Projects Agency (DARPA) is sponsoring a workshop on Nastic Structures (NAST). The workshop will be held July 1, 2003, at the Executive Conference Center in Arlington, Virginia. Nastic and tropic movements in plants enable actions such as sun tracking and the capture of prey. Of interest to this workshop are technological developments that will enable the development of a practical material system that can mimic the ability of plants to generate large strains while carrying significant structural loads. The ultimate goal is the development of highly controllable and reversible material systems that can generate 10 Megapascals and 20% in blocked stress and free strain, respectively. The workshop is intended to help researchers in various disciplines self-assemble into teams capable of developing plant inspired actuation systems that will ultimately have application in military adaptive or morphing structures. Plant actuators possess a number of common features that may prove useful in future motion control and shape control systems: 1) Structural shape changes are accomplished through size changes in antagonistic volumes of plant tissue. For example, bending is accomplished when plant tissue on top of a branch gets larger while the tissue on the bottom shrinks. Bulk strains on the order of 10-20% have been observed and response times on the order of seconds to tens of seconds are common. In special cases large motions are accomplished in milliseconds, but these motions are not quickly reversible; 2) The root cause of the motile response is a change in cell size driven by pressure variations within the plant cells. The small size and large numbers of plant motor cells provide redundancy in actuation; 3) The pressure state in the cell is controlled by the ion transport characteristics of the cell wall. The ability of cell walls to transport and contain fluid providesprovides actuation and compressive strength. The cell walls themselves provide strength in tension. Thus the plant is essentially aan adaptive composite structure; 4) The transport characteristics of the cell wall are controlled by the presence or absence of both electric fields and ions. The ability to respond to both chemical and electrical signals provides control redundancy. It is anticipated that teams ultimately proposing in this area may need expertise in the chemistry, design, control, and mechanics of both plant actuation systems and conventional actuation systems. A clear military application for the proposed technology is also required. Please access the workshop website for further details including registration and abstract submission. The event website is www.eventmakeronline.com/dso/view/Index.asp?meetingid=186. The workshop registration fee is $73.00 and includes all workshop activities, continental breakfast, and working lunch. Registration cutoff is June 11, 2003, or at attendance capacity, whichever occurs first. Space is limited and it is recommended that you register early. For further administrative information contact [email protected]. The technical point of contact is Dr. John Main ([email protected]). Please refer to the NAST workshop in all correspondence. This announcement is NOT a request for proposals. No solicitation document is available at this time.