Contact Dynamics and Damping in High-G Digital Accelerometer

Graduate Student: Venkattraman Ayyaswamy (AAE)

Undergraduate Students: Devon Parkos (AAE)

Collaborators: Prof. Wayne Chen (Purdue AAE/MSE), Prof. Dimitrios Peroulis (Purdue ECE), Nithin Raghunathan (Purdue ECE)

A new damping model is being developed for thick microbeams (Figure 1) experiencing high levels of acceleration (up to 100,000 G). Its primary use will be performing dynamic simulations used for the development of high-g digital accelerometers composed of many different microbeams. Predicting the aerodynamic damping (Figure 2) is important because it significantly affects the time a beam takes to contact another surface, greatly influencing both the response time and stresses occurring in the beam itself.

Figure 1. Sample Cantilever Microbeam Setup for use in Accelerometer [1].

Figure 2. Beam Cross-section Near Contact with the Surface [1].

The aerodynamics are complicated by the small beam size, which pushes the aerodynamic behavior into the rarefied regime. By analyzing the aerodynamics and determining a functional relationship between gap size and the aerodynamic damping coefficient, dynamic simulations were run yielding the following data (Figures 3 and 4) for time the beam takes to contact and reopen. The data shows the comparison of the new model to both an existing model and experimental data. As is shown in the figures, the changes between aerodynamic damping models can significantly affect the behavior of the microbeam and consequently the performance of the accelerometer in development.

Figure 3. Time to Contact Comparison between Damping Models [1].

Figure 4. Time to Reopen Comparison between Damping Models [1].


[1] D. Parkos, N. Raghunathan, V. Ayyaswamy, A. Alexeenko, D. Peroulis, "Near-Contact Damping Model and Dynamic Response of Microbeams under High-g Loads", In Proceedings of International Conference on Microelectromechanical Systems (MEMS 2011), January 23-27, 2011.