If a machine experiences a problem because of an unexpected resonant frequency, high local flexibility, a weak element in the system, an unexpectedly high dynamic load, or excessive sensitivity to known dynamic loads, structural failure may occur.

Finite element (FE) analysis helps find correction factors that make more cost-effective, simplified analyses as accurate as possible. This approach provides flexibility factors for reinforced piping joints, adjustment factors for calculating forces transmitted by reciprocating compressors to their foundations, and the rotor stiffening effect of interference fits in turbomachines.

Finite element predictions identified high-stress locations that led to stress corrosion cracking failures in the centrifugal compressor wheel to the right. FE analysis guided design changes that improved the integrity of the compressor. 

Southwest Research Institute (SwRI) engineers complement their field problem solving and failure analyses services with finite element analysis to diagnose causes and develop design solutions.

Analysis of 3-point mounted compressor skids, designed for offshore structures, helps to evaluate skid responses. Animation: Windows Media.		High-frequency, unbalanced gas load excitation of a reciprocating compressor skid is evaluated by finite element analysis. Animation: Windows Media.

Structural Integrity Assessment

SwRI applies finite element methods to evaluate structural dynamic characteristics of skid-mounted centrifugal and reciprocating compressors used for gas compression.

The illustration (above) shows a gas turbine mode of vibration identified by finite element analysis. The illustration (below) shows the vibration-mode shape of a skid-mounted reciprocating compressor caused by high-frequency gas forces. Predicting harmonic response to applied dynamic forces helps SwRI engineers assess the severity of resonant vibration. Animation helps identify the elements that contribute most strongly to troublesome modes of vibration and clarifies the most effective locations for bracing or stiffening of the structure.

For more information about our machinery vibration services, finite element dynamic analysis capabilities, or how you can contract with SwRI, please contact Jeff Moore, Ph.D., at jmoore@swri.org or (210) 522-5812.

machineryvibration.swri.org