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During the last few years, there have been significant investments in the development of micro-electro-mechanical systems (MEMS) for the monitoring and control of weapons stockpiles and new weapons systems. However, in order for MEMS to be included in these stockpiles, they must satisfy stringent performance and reliability requirements, including survival after billions of cycles of operation, acceleration/deceleration up to 30,000g lasting milliseconds, and temperatures from -50 to 80°C. Despite significant effort, MEMS have not thus far been able to meet these criteria, and experience unexpected failures, the reasons for which are poorly understood. If these problems could be solved, MEMS would find widespread deployment.
Typical radio-frequency micro-electromechanical system (RF MEMS). The device has a length of about 400
microns long.
The objective of the PRISM center is to significantly accelerate the integration of MEMS technologies into stockpile monitoring and weapons systems through the use of predictive, validated science and petascale computing. The Center seeks to understand, control, and improve the long-term reliability and survivability of MEMS by using multiscale multiphysics simulation, from atoms to micro-devices, to address fundamental failure mechanisms. The central focus is on a single class of contacting radio-frequency (RF) metal-dielectric capacitative MEMS switches, though the advances made in PRISM will impact the development of a wide range of civilian and military MEMS as well.
PRISM research addresses five Center thrusts including:
- contact physics, including dielectric charging, current channeling, contact-area damage, and stiction,
- the electro-thermo-mechanical membrane response, including macro-scale materials modeling based on microstructural evolution of defects, dislocations and vacancies, and thermal modeling coupling sub-micron and continuum descriptions,
- multiscale modeling of aerodynamic damping, transitioning dynamically from continuum to rarefied descriptions as the metal-dielectric contact closes,
- uncertainty quantification in this complex multiscale multiphysics environment, and
- the integration of this wide range of models and numerics into a coherent simulation system.
The multiscale resolution of failure mechanisms requires billion-atom simulations over 1-10 million time steps at the atomic scale, and tens of millions of degrees of freedom over 1-10 million time steps at the macroscale; the inclusion of uncertainty quantification increases computational effort by an order of magnitude, necessitating petascale computing.
Supporting these five thrusts are three cross-cutting technology groups, including
- Computational Science and Engineering (CSE) to provide a strong backbone of algorithmic and petascale computing expertise,
- Software Engineering, to design, develop, maintain and support high-quality software, and
- Verification and Validation (V&V), a substantial Center effort to address issues specific to multiscale multiphysics simulations in microsystems.
An extensive experimental program is underway conducted at Purdue's state-of-the-art Birck Nanotechnology Center to augment published data with validation-quality measurements, particularly on microstructural characterization, and to develop a first-of-its-kind validation database for uncertainty quantification in microsystems. A 5-year simulation program is underway, starting with system simulations based on continuum physics, adding complexity yearly, and culminating in petascale MEMS simulations under both normal and high strain- rate loading conditions, and in harsh environments.
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