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Stress & Fatigue AnalysisFor Piping, Valves, Vessels, Heat Exchangers
2 | www.gantner-instruments.com
Thermal Load Definition
Based on thermal loads gathered by the process automation system or dedicated monitoring system, transients for the analysis are created.
In case input data from the normal process instrumentation is used the fluid temperature and heat transfer coefficient are defined. In case data from a monitoring system with temperature sensors at the outer surface of a component or pipe is used, Fourier’s heat transfer equation is solved inversely.
Gantner Instruments engineering service provides stress and fatigue analysis for thermal transient
loaded components of power plants or other industrial plants and applications.
Stress and Fatigue Analysis for Thermal Transient Loaded Mechanical Components
Stress & Fatigue Evaluation According to Codes & Standards:
ASME Section III NB3200 RCCM B3200 KTA 3201.2 / 3211.2 NUREG / CR6909
Thermal load from process automation or dedicated monitoring system and definition of load transients
Temperature evolution on nodes of FE model
Periode Occurence Event
N_Fuel loading
∑D
1985 – 2016 15 31 0.23
1985 – 2025 15 40 0,3
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FE Modelling
For the thermal and mechanical analysis a detailed finiteelement model is created.
Finite Element Software
Our analysis are performed with Code_Aster solver developed by EDF R&D and released under GNU GPL license.
Mechanical Analysis
The thermal transient field of the analyzed pipe or component is used for the stress & strain calculation. The complete stress tensor (normal & shear stress) is evaluated and stress ranges according to Tresca or von Mises are determined under consideration of plasticity factors, weld seam factors in compliance with the codes & standards.
Stress is linearized on evaluation sections, the comparison with the allowable stress limit will inform if an elastic (Ke=1) or a simplified elasticplastic analysis (Ke>1) should be performed.
Fatigue Analysis
For each considered transient the alternate stress will be determined with a peakvalleymethod or a rainflow algorithm. The allowable number of cycles corresponding to each alternate stress is obtained from the corresponding fatigue curve. The sum of all the partial usage factors over the whole lifetime of the component should be lower than 1 to exclude fatigue damage.
Environmentally Assisted Fatigue
R&D topics are focusing on the influence of medium effects on fatigue lifetime. These parameters can be considered in the evaluation as experimental fatigue curves or numerical correction factors (Fen).
Equivalent stress
Thermal field calculation
Modelling of heat exchanger
Bending moment on Tjunction
Evaluation sections on instrumentation nozzle
Fatigue evaluation with end of life prediction at the highest loaded section
Test and Measurement Technology. Designed for You.
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