Operational modal analysis of the Artemis I dynamic rollout test

Operational modal evaluation (OMA) strategies have been used to determine the modal traits of the Artemis I launch automobile through the Dynamic Rollout Check (DRT) and Moist Costume Rehearsal (WDR) configuration previous to launch. Forces induced throughout rollout and on the launch pad usually are not immediately measurable, thus necessitating a singular method.

NASA is growing the SLS to assist lunar and deep space exploration. SLS is built-in contained in the Automobile Meeting Constructing (VAB) on the cell launcher (ML), which helps the built-in SLS launch automobile throughout transport to the pad by means of lift-off. The ML additionally supplies the gasoline, energy, and information umbilicals working to the SLS and Orion Multi-Goal Crew Automobile (MPCV), in addition to crew entry to the MPCV crew module.

The ML weighs ~10.6 million kilos and is over 380 ft tall. Within the spring of 2022, the SLS was transported on the ML from the VAB to Launch Pad 39B (Determine 1) utilizing the NASA crawler transporter (CT) to make this 4.2 mile trek, which takes ~8 hours. The CT alone weighs ~6.3 million kilos.

Though the rollout surroundings produces comparatively small launch automobile structural masses compared to launch and ascent masses for many buildings, the induced masses are totally consultant of all loading throughout your entire automobile, which isn’t possible to copy utilizing localized shakers as was carried out within the Built-in Modal Check.

As talked about, forces induced throughout rollout and on the launch pad usually are not immediately measurable, and OMA strategies have been used to determine the modal traits of Artemis I within the DRT and WDR configurations. WDR, which generally consists of vehicle fueling and different operations to show launch readiness, included a number of days of on-pad operations.

Knowledge collected for the WDR configuration, with partially stuffed core gasoline tanks and with out the CT below the ML, supplied engineers one other mannequin configuration to examine (Determine 2).

Acquisition and processing the information from greater than 300 accelerometers situated on Artemis I, ML, and CT was completed by a cross-program group of engineers and technicians from throughout the Company, together with from SLS, Exploration Floor Techniques, and the NESC. Utilizing analytical strategies developed from earlier rollout checks mixed with new data-processing methodologies, the group processed information from preselected CT velocity increments throughout rollout and on-pad throughout WDR.

By making the mandatory modifications to the built-in fashions to match each the DRT and WDR configurations, the group was ready to make use of these outcomes to assist make sense of what was being seen within the check information. This proved to be required for OMA testing on this construction, given the kind of advanced excitation that was being noticed.