In fatigue life calculations of structural components, methods based on fatigue damage accumulation hypotheses are commonly used. In addition to selecting an appropriate hypothesis, these methods require knowledge of the load spectrum, which usually consists of a set of sinusoidal cycles with variable parameters (Sa and Sm), and fatigue characteristics, typically in the form of a Wöhler fatigue curve. In the design and engineering process, due to the lack of physical objects and the inability to perform measurements, knowledge of this data is limited.In view of the above, this paper describes a method for calculating the fatigue life of structural components based on the relationships between fatigue life curves determined under constant-amplitude conditions (Wöhler curves) and programmed or random loading conditions. The proposed method has been experimentally verified using test results from steel structural components (welded tubular joints and components with geometric notches).
INITIAL FATIGUE LIFE CALCULATION METHOD OF MOTOR VEHICLE ELEMENTS
Methods based on fatigue damage accumulation hypotheses are commonly applied in fatigue life calculations of constructional elements. Knowledge of the loading spectrum is essential apart from the selection of a proper hypothesis.
The spectrum usually is a set of sinusoidal cycles with variable parameters (Sa and Sm) fatigue characteristics – usually as Wohler curve. Due to the lack of material objects and possibility of measurements there is weak knowledge of mentioned data in the design process.
With regard to the above the paper includes the description of a fatigue life calculation method based on relations among fatigue life curves in constant amplitude (Wohler curves) and programmed or random loading conditions.
The proposed method was experimentaly verified with the results of steel constructional elements (welded pipe nods and elements with geometrical notches). (…)
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Source: Logistyka Magazine
Preliminary fatigue life calculation method for motor vehicle components – PDF file for download