NASA'S Successful "Can Crush" Will Aid Heavy-Lift Rocket Design

"This type of research is critical to NASA developing a new heavy-lift
vehicle," said NASA Administrator Charlie Bolden. "The Authorization
Act of 2010 gave us direction to take the nation beyond low-Earth
orbit, but it is the work of our dedicated team of engineers and
researchers that will make future NASA exploration missions a reality."

The aerospace industry's shell buckling knockdown factors date back to
Apollo-era studies when current materials, manufacturing processes
and high-fidelity computer modeling did not exist. These new analyses
will update essential design factors and calculations that are a
significant performance and safety driver in designing large
structures like the main fuel tank of a future heavy-lift launch vehicle.

During the test, a massive 27.5-foot-diameter and 20-foot-tall
aluminum-lithium test cylinder received almost one million pounds of
force until it failed. More than 800 sensors measured strain and
local deformations. In addition, advanced optical measurement
techniques were used to monitor tiny deformations over the entire
outer surface of the test article.

The Shell Buckling Knockdown Factor Project is led by engineers at
NASA's Engineering and Safety Center (NESC), and NASA's Langley
Research Center in Hampton, Va. NASA's heavy-lift space launch system
will be developed and managed at Marshall.

"Launch vehicles are thin walled, cylindrical structures and buckling
is one of the primary failure modes," said Mark Hilburger, a senior
research engineer in the Structural Mechanics and Concepts Branch at
Langley and the principal investigator of the NESC's Shell Buckling
Knockdown Factor project. "Only by studying the fundamental physics
of buckling through careful testing and analysis can we confidently
apply the new knowledge to updated design factors. The outcome will
be safer, lighter, more efficient launch vehicles."

Leading up to this full-scale test, the shell buckling team tested
four, 8-foot-diameter aluminum-lithium cylinders. Current research
suggests applying the new design factors and incorporating new
technology could reduce the weight of large heavy-lift launch
vehicles by as much as 20 percent.

"Marshall's Structural and Dynamics Engineering Test laboratory is
uniquely suited for shell buckling testing," said Mike Roberts, an
engineer in Marshall's structural strength test branch and the center
lead for this activity. "Originally built to test Saturn rocket
stages, the capabilities found here were essential to developing the
lightweight space shuttle external tank flying today and for testing
International Space Station modules."

For this test, Marshall led all test operations including the
engineering, test equipment design and safety assurance. Lockheed
Martin Space Systems Company fabricated the test article at
Marshall's Advance Weld Process Development Facility using
state-of-the-art welding and inspection techniques. Langley engineers
led the design and analysis of the test articles, defined the test
requirements, and developed new optical displacement measurement
standards that enabled highly accurate assessment of the large-scale
test article response during the test.

In the future, the shell buckling team will test carbon-fiber
composite structures that are 20-30 percent lighter than aluminum and
widely used in the automotive and aerospace industries.

For more information, visit:

http://www.nasa.gov/exploration

Source: NASA

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