Optimization of high-precision measurement device

Project Description

In this project, SimulaX Engineering was tasked with performing a modal analysis and center of gravity (COG) calculation for a complex assembly. The goal was to ensure that the first eigenfrequencies met specific requirements while maintaining a horizontally centered COG.

This device has two coaxially aligned rotating axes holding a large rotor blade with an analytic instrument attached to it. The rotors are placed on top of an XY positioning stage on a granite base. As the scientific results are heavily impacted by any vibrations of the analytic intruments, the aim of this project was to reach a certain minimum first eigen frequency.

Modal analysis

The initial modal analysis revealed that the eigenfrequencies of the original design were approximately 40% lower than the requirement, both in the upper and lower positions. Detailed investigation identified the rotor structure as the primary contributor to the low frequencies.

To address the center of gravity challenge, we developed a custom Python script that automatically adjusted counterweight positioning on the rotor. The script was designed to be universal, ensuring functionality even if assembly parameters or configurations changed—automatically recalculating and maintaining COG balance.

Meeting the minimum first eigen frequency requirements

Based on our findings, our main recommendation was using a double-sided rotor plate to significantly improve both the structural stiffness and the balance of the assembly. Moreover, increasing the distance between the rails and wagons, as well as reinforcing certain bearing attachment points and the frame supporting the rotating axles, resulted in minor improvements.

Conclusion

By implementing our suggested modifications, the assembly successfully met the modal analysis criteria, and the machine’s center of gravity was effectively balanced through the automated Python script. This solution not only fulfilled the project requirements but also enhanced the overall robustness and performance of the design.