To accurately assess the fatigue reliability of fillet welds at the bottom of molten salt tanks during service,a fatigue reliability assessment method based on the stress-strength interference theory is introduced.This method involves randomizing stress-influencing factors and fatigue model parameters.The range of typical molten salt liquid level variations and their occurrence frequencies are obtained through the rainflow counting method.A numerical model of fillet welds,accurately representing their dimensions,is created to analyze stress distribution.By utilizing a normal distribution model for stress-influencing factors such as fillet weld size and load,the Latin hypercube sampling technique enables the statistical sampling necessary to establish the distribution model of equivalent structural stress at the fillet weld toe.The primary stress-life curve parameters within the fatigue life model as per the ASME BPVC.Ⅷ.2-2023 standard is randomized.Based on the stress-strength interference theory,a fatigue reliability assessment model for fillet welds is established.An illustrative analysis of the fatigue reliability of fillet welds at the bottom of a low-temperature molten salt tank of a solar thermal device reveals six typical operational scenarios for liquid level fluctuations within a quarter,with peak variations spanning from 1.55 m to 12.39 m.The highest stress on the fillet weld is identified at the inner weld toe,measuring 301.5 MPa.The average fatigue lifespan of fillet welds subjected to various loads is calculated at 46 a.Following 3 a of service,the probability of fatigue failure of the fillet weld stands at 0.040 6,escalating to 0.335 9 after 30 a of operational service.
molten salt tankfillet weldstress-strength interference modelfatigue reliability
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