A Mathcad computer program largely automates the design and analysis of the restraint layer (the primary load-bearing layer) of an inflatable vessel that consists of one or more sections having cylindrical, toroidal, and/or spherical shape(s). A restraint layer typically comprises webbing in the form of multiple straps. The design task includes choosing indexing locations along the straps, computing the load at every location in each strap, computing the resulting stretch at each location, and computing the amount of undersizing required of each strap so that, once the vessel is inflated and the straps thus stretched, the vessel can be expected to assume the desired shape.

Prior to the development of this program, the design task was performed by use of a difficult-to-use spreadsheet program that required manual addition of rows and columns depending on the numbers of strap rows and columns of a given design. In contrast, this program is completely parametric and includes logic that automatically adds or deletes rows and columns as needed. With minimal input from the user, this program automatically computes indexing locations, strap lengths, undersizing requirements, and all design data required to produce detailed drawings and assembly procedures. It also generates textual comments that help the user understand the calculations.

This program was written by Gary Spexarth of Johnson Space Center. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Software category.

This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to

the Patent Counsel
Johnson Space Center
(281) 483-0837.

Refer to MSC-23906.

NASA Tech Briefs Magazine

This article first appeared in the February, 2007 issue of NASA Tech Briefs Magazine.

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