CHPP Vibration Survey
Mincka was commissioned to run a vibration survey in the CHPP building in Emerald, Queensland.
The customer was concerned about the excessive vibration on the centrifuges level in the CHPP building. A noticeable drifting motion from side to side horizontally, which was periodic in nature, was identified. In addition, some members appeared to be affected by the vibration generated by the excitation of the machinery on this floor.
The Challenges
The main challenge of this project was the constraints related to the installation of sensor and data acquisition systems. In addition, the deployment of an entire team of modal testers in the CHPP building was too cost-prohibitive. Finally, the available time span to conduct the measurements was very short, so installing wired sensors was not feasible.
The Solution
Mincka performed a series of measurements using wireless accelerometers, which are portable, do not require a fixed power source, and are easy to deploy. We carried out a series of measurements using a Rover-reference technique; one accelerometer acts as a reference, while the others move (rove) around the designated area. This allows us to get several measurement points along the building, capturing a complete, dynamic response.
With the recorded data we performed a experimental modal analysis. We identified the natural frequencies of the building, and were able to identify which ones were affected by the excitation generated by the machines. In addition, we used a finite element model to run a time-history analysis, in order to visualize all of the movement and the response of the structure.
The Impact
Mincka identified that the acceleration levels recorded in the building are harmful to the personnel working near the area. ISO standards were used as the criterion for the establishment of allowable acceleration levels, and the magnitude of the acceleration exceeded those thresholds. We recommended relocation of the personnel to a different area, to prevent incurring any health and safety risks. Mincka also provided recommendations for the maintenance and modification of the centrifuges’ insulators, to reduce the energy transfer between the machines and the structure.
