Structural Analysis Predicts Vibration for Pumping Platforms: A Case Study on Mechanical Solutions, Inc.

Mechanical Solutions, Inc. (MSI) is a leading mechanical engineering firm that performs consulting and R&D, along with design, analysis, and testing services for a diverse range of project types throughout the world. In this case, MSI was subcontracted to increase the capacity of a pumping station in New Orleans, a city prone to flooding and severe weather events. The company's expertise in mechanical engineering and its ability to leverage advanced technology like ANSYS Mechanical software were critical in addressing the challenges of this project.

In the aftermath of Hurricane Katrina, one of the deadliest hurricanes in the United States, Mechanical Solutions, Inc. (MSI) was subcontracted to increase the capacity of a pumping station in flood-prone New Orleans. The challenge was to evaluate the vibration responses of the platform during the operation of high-power mechanical equipment. During major weather events, these high-power pumping units must work at full capacity to drain excess water out of sub-sea-level areas. The heavy equipment produces vibrations and other stresses that can cause the massive platforms supporting the equipment to fail. MSI engineers faced numerous challenges in assessing and addressing design problems of the partially submerged pumping station platforms. All design issues had to be identified and addressed before any construction began, and the project needed to be completed prior to the onset of the next hurricane season.

MSI utilized ANSYS Mechanical software to simulate pumping platform stresses and vibrational responses to ensure that the system would perform optimally during storms. The engineers imported solid models of the equipment into ANSYS Mechanical and used a combination of solid, shell, beam, and mass point elements to create a mesh of the truss platform support structure. This resulted in a structural dynamic model with approximately 5 million degrees of freedom (DOF). They employed substructuring techniques available in ANSYS Mechanical to significantly reduce DOF without losing accuracy. They performed modal analysis followed by a superposition harmonic response analysis and identified worst-case loading conditions. Virtual sensors were placed in various locations to provide vibrational frequency response functions in a forced-response FEA analysis. They also performed an acoustic evaluation of the discharge piping to assess the potential for acoustic resonance.

• The use of ANSYS Mechanical software allowed MSI to effectively simulate and predict the stresses and vibrational responses of the pumping platforms. This ensured that the system would perform optimally during storms, a critical requirement given the flood-prone nature of New Orleans. The successful completion of this project before the onset of the next hurricane season demonstrated MSI's ability to address complex design problems under tight deadlines. The platforms and pumps' successful performance during Hurricane Gustav in 2008 further validated the accuracy of the ANSYS simulation results and MSI's expertise in mechanical engineering.

• The structural dynamic model created had approximately 5 million degrees of freedom
• The use of substructuring techniques significantly reduced degrees of freedom without losing accuracy
• The platforms and pumps successfully kept flood waters in check during Category 2 hurricane Gustav in 2008, validating the accuracy of the ANSYS simulation results