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Justin G. Chen

Publications and source records attributed to Justin G. Chen.

Motion Magnification to Visualize the Modes of Space Structures

Traditional structural testing involves using accelerometers and strain gages to measure the motion. While this traditional instrumentation suite has proven accurate, it is limited to capture data only in the discrete locations where the transducers are placed. Additionally, applying the instrumentation can be a difficult and labor intensive task. By using video cameras, the motion of the test article – such as a launch vehicle or launch vehicle payload – can be easily captured at any location in the field of view and easily visualized using a post-processing technique called Motion Magnification. It is also much easier to place video cameras to measure motion rather than having to place contact sensors, especially when placement locations can be limited on final flight hardware. Recently, a team of MIT Lincoln Laboratory (MITLL) and NASA Marshall Space Flight Center (MSFC) have been collaborating to use Motion Magnification to measure the dynamics of large space structures. This presentation will detail some of the results of this collaboration.

Eric Colby Stewart↗

To the Moon! Space Launch System Modal Testing with Video and Motion Magnification

MIT Lincoln Laboratory and NASA Marshall Space Flight Center have been collaborating on using video camera measurements and motion magnification for modal testing of large aerospace components for several years. This presentation will discuss results from the Space Launch System Integrated Modal Test (IMT) and Dynamic Rollout/Rollback Test (DRRT) in support of the Artemis I mission. During the IMT, the data collection focused on operational mode shapes. In addition, the cameras were repositioned mid-test to better understand the physics of a low-frequency torsion mode. The non-contact nature of video data capture allowed for the quick redeployment of the cameras while not causing any delay in test schedule, whereas traditional instrumentation would have required a pause in testing to attach the sensors to the test article. The motion magnification analysis was able to find the low-frequency operational mode shapes and help the test team better understand the physics of the torsion mode. Building upon the success of the IMT motion magnification work, a camera system was used during the DRRT to find operational mode shapes, if the physics of the low-frequency torsion mode remained with different boundary conditions, and relative deflection of the vehicle and ML tower during the roll. In this paper we will present operational mode shape results, discuss the physics of the torsion mode, and review experimental setup idiosyncrasies to help the community in designing video camera measurement systems.

optical↗