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Finite Element Analysis of Advanced Technology Laboratories Isolation Slab Conditioning System

Jeffrey T. Fong and Zhengdong Wang, ACMD
Stephen J. Treado, Building and Fire Research Laboratory
E. Clayton Teague, Manufacturing Engineering Laboratory
Barry Bernstein, Illinois Institute of Technology
David E. Dietrich, Desatek, Inc.

NIST is currently engaged in the planning of a new facility known as the Advanced Technology Laboratories (ATL). The mission of ATL requires the ultimate in environment conditions such as precise temperature and humidity control, air cleanliness, clean electrical power, and absence of vibration. Among the many rigorous environmental control requirements, the most challenging two tasks of the project are (a) to control the temperature in some of the laboratories to +/- 0.01 deg.C accuracy, and (b) to control the vibration amplitudes of rms displacement to 0.025 micrometer at frequencies between 1 and 20 Hz, and rms velocity to 3 micrometer/sec at frequencies above 20 Hz and less than 100 Hz.

To ensure that the specified accuracies be achieved in the final product, i.e., a constructed building based on a well-thought out design with analysis to simulate all conceivable disturbances, NIST and its architect, Henningson, Durham & Richardson (HDR), conducted a study of high accuracy temperature control concepts and concluded that a Temperature Control Test Module be built by the NIST Building Environment Division to test various control concepts. A similar conclusion was also reached for the vibration isolation module.

Construction for the Temperature Test Module began sometime in the Fall of 1994 and is expected to be completed by April 1995. Dr. Stephen Treado is the project engineer for the experimental program. A pre-design effort for the vibration isolation module was undertaken by Dr. E. Clayton Teague. For both modules, Dr. Jeffrey Fong was invited to serve as the mathematics consultant to develop a finite-element model, with the appropriate error monitoring and mesh optimization routines, to simulate the steady- state and transient responses of two HDR-designed structural systems, one for temperature control and the other for vibration isolation. In addition, when the simulation results indicate that the HDR's design fails to meet the NIST specifications, Fong's model will be used to analyze design changes to be proposed jointly by Fong and Treado.

The project is important because the precision-driven problems need a special type of analysis and a routine application of commercially-available finite element packages is not accurate enough to accomplish the tasks. Consequently, new tools to embed routines such as LINPACK's code for calculating conditioning number of a matrix need to be developed to monitor error growth. Automatic mesh-generation routines need to be calibrated from benchmark problems of known solutions to ensure that an optimum mesh design is used to generate the best solution.

The analysis project was being done at ACMD because of (a) availability of ACMD's expertise, and (b) saving of critical time in coordination between the analyst and the experimentalist. The project is time-critical because there is a schedule to meet in completing the construction of this project.

A 46-page report with 27 drawings and 8 appendices was published in Nov. 1994 (NISTIR 5528) by Fong and Treado as the first of a series of reports on this subject. The next progress reports are (a) an error analysis report by Fong, Bernstein, Wang, and Dietrich, and (b) a finite element analysis report for the air conditioning system by Treado and Fong.

next up previous
Next: Concurrent Engineering Design Up: Other Projects Previous: Other Projects