Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sandia assists NASA with space shuttle rollout test

20.04.2005


Project looked at massive mobile launch platform, shuttle transporter



Sandia National Laboratories recently conducted a series of tests to help NASA understand the fatigue on the space shuttle caused during rollout from the Kennedy Space Center assembly building to the launch pad - a four-mile trip.

The tests are part of NASA’s return-to-flight mission, with the first flight scheduled between May 15 and June 3.


Sandia, a National Nuclear Security Administration laboratory, helped NASA design the test and instrumentation to measure the dynamic vibration environment during rollout. Sandia also computed the input forces the crawler applies to the Mobile Launch Platform (MLP). These computations are being used by Boeing and NASA to determine the fatigue life for critical shuttle components.

Sandia engineer Tom Carne assisted in a series of tests beginning in November 2003 to develop the data necessary to understand the environment and the response of the space shuttle vehicle during rollout.

"NASA requested Sandia to assist them in this project because of our expertise in planning and conducting structural dynamic tests on very large structures," Carne says.

Sandia’s solid mechanics/structural dynamics group has done numerous structural analysis projects on large structures including the I-40 Rio Grande bridge in Albuquerque, large wind turbines up to 110 meters tall, and the Department of Energy’s Armored Tractor. One of the group’s main missions is analysis and testing of the shock and vibration environments for weapons.

The three-million-pound shuttle sits on the eight-million-pound mobile launch platform, which is carried by a six-million-pound crawler. The crawler transports the vehicle and platform four miles from the Vehicle Assembly Building to the launch pad.

Moving the shuttle that distance, which normally takes five to six hours at 0.9 mph, had been considered a relatively low-stress process during most of the life of the shuttle system. As the equipment ages, however, more emphasis is being given to understanding how the rollout may fatigue the transport system.

Data were collected for rollouts of the MLP-only and the MLP with the two solid rocket boosters, at five different speeds ranging from 0.5 to 0.9 mph. For the tests more than 100 accelerometers were placed on the MLP, crawler, and solid rocket boosters. A data acquisition system installed inside the MLP for the road test measured and recorded the accelerations. The data were analyzed so that the character of the rollout environment is understood and can be analytically imposed on the shuttle using a finite-element computer model to predict fatigue damage to critical components. Even though these stresses are much lower than those seen during the launch, the five- to six-hour duration of the transport and the low-frequency vibration could cause fatigue in components within the orbiter.

Carne says the rollout analysis team determined that there are two families of forcing harmonics caused by the crawler drive train that vibrate the platform as a function of crawler speed, in addition to the random inputs induced by the road bed. Fortunately, he says, the harmonic forcing frequencies can be adjusted by merely changing the drive speed of the crawler, resulting in less damaging frequencies.

The team used a Sandia-developed algorithm, the Sum of Weighted Accelerations Technique (SWAT), to estimate the applied forces. Carne says the SWAT results were beneficial in choosing a new rollout speed that will extend the fatigue life of the shuttle components that were affected by rollout.

The SWAT-generated input forces have subsequently been used as the force input for NASA’s NASTRAN structural analysis of the mobile launch platform, emulating the test conditions. The correlation between the rollout-measured data and the predictions from the NASTRAN analysis has engendered confidence in both the SWAT-computed forces and the NASTRAN model of the MLP and solid rocket boosters, he says.

The analyses showed that the shuttle’s vibration response can be much reduced when the driving frequencies are shifted away from the shuttle’s own resonant natural frequencies. They helped NASA determine that merely reducing crawler speed from 0.9 mph to 0.8 mph would significantly reduce the vibrations in the shuttle by shifting the impact frequency of the crawler treads.

Michael Padilla | EurekAlert!
Further information:
http://www.sandia.gov

More articles from Physics and Astronomy:

nachricht Long-lived storage of a photonic qubit for worldwide teleportation
12.12.2017 | Max-Planck-Institut für Quantenoptik

nachricht Telescopes team up to study giant galaxy
12.12.2017 | International Centre for Radio Astronomy Research

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Long-lived storage of a photonic qubit for worldwide teleportation

12.12.2017 | Physics and Astronomy

Multi-year submarine-canyon study challenges textbook theories about turbidity currents

12.12.2017 | Earth Sciences

Electromagnetic water cloak eliminates drag and wake

12.12.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>