Providing Vibration & Fatigue Solutions on Equipment
Vibration and fatigue troubleshooting, testing & analysis services on equipment. Should issues arise, we design solutions – ensuring structural integrity, minimizing risk and controlling costs for owners/users.
Most equipment vibration problems are due to thermal, mechanical, acoustic, or flow related excitation – and if left unchecked, will cause fatigue and subsequent equipment failure, which may lead to greater repair costs.
Components vibrate at particular natural frequencies. These frequencies and resulting mode shapes can be found using modal and vibration analysis. Often, simple analysis can be performed, while for more complex systems, finite element analysis is performed to determine the dynamic response.
Once vibration and thermal / fatigue issues are identified, we design solutions to ensure structural integrity. Examples include:
- Troubleshooting, analysis and repair of rotating equipment including compressors, fans and shafts
- Vibration, seismic & fatigue analysis of piping, tanks, vessels, skids and welded structures
- Shock and vibration analysis of nuclear equipment in land-based and shipboard applications
Above – Vibration and Modal Analysis of an Industrial Impeller
Low Cycle / High Cycle Fatigue Analysis
Fatigue (from cyclic loading) is one of the most frequent causes of failure in pressure vessels, piping and process equipment. A vibrating component or system often leads to fatigue – which eventually leads to equipment malfunction, or catastrophic failure. Fatigue cracks usually initiate at the surface, and for this reason, the condition of the surface and the environment are important factors influencing fatigue behavior.
Low cycle fatigue failures result when a material is stressed above its elastic limit. This is the limit a material my be stressed without permanent alteration of size or shape.
High cycle fatigue failures occur under repetitive (e.g., cyclical, harmonic, and random vibration) stresses well below the yield strength of the material.
We perform (thermal / fatigue) analysis of non-welded and welded components. Tom O’Donnell performs vibration, fatigue and failure analysis to ASME and other relevant Codes. Bill O’Donnell Sr. continues to serve as a Contributing Member of the ASME Boiler and Pressure Vessel Code Subgroup on Fatigue Strength – and has published numerous papers on fatigue and failure analysis. One such paper is Code Design and Evaluation for Cyclic Loading – ASME Sections III and VIII.
Fatigue analysis is performed per ASME Section III Class 1 and Section VIII Division 2. The fatigue design life evaluation procedures in Section III of the ASME Boiler and Pressure Vessel Code were originally developed in the U.S. Naval Nuclear Program. Those involved were Bill O’Donnell, (Bernie) Langer, W.E. (Bill) Cooper and James (Jim) Farr – who, in the late 1950’s and early 1960’s developed the initial formulation of this technology in the Tentative Structural Design Basis for Reactor Pressure Vessels and Directly Associated Components, which became known as “SDB-63.”
Section III of the ASME Code “Vessels in Nuclear Service” was the first to include specific Code rules to prevent low cycle fatigue failure. Its first edition was published in 1963; Section VIII, Division 2, “Alternate Rules for Pressure Vessels” followed in 1968.
- Welded Assemblies
- Lifting Devices
- Power Generation
- Pumps & Valves
- Rotors & Shafts
- Medical Equipment
- Electronic Equipment
Give Us a Call to Discuss your Engineering Challenges.