Structural Reliability Analysis of Railroad Tank Cars Subjected to Fatigue and Corrosion

Reliability analysis of tank car structures undergoing fatigue crack growth and general corrosion (tank wall thinning) is illustrated to support informed decision-making and planning for reliability-centered maintenance. Two specific mechanisms that contribute to tank car deterioration are considered: (1) corrosion with negligible fatigue crack growth; and (2) corrosion-accelerated fatigue crack growth. Reliability analysis of corrosion-accelerated fatigue crack growth is performed with a time-dependent tank wall thickness reduction and a fatigue crack growth model that incorporates a three-degrees-of-freedom surface crack obeying Walker crack growth law under tank car spectrum loading. System reliability problems involving multiple corrosion sites are considered to illustrate important features of failure probability for a series system in relation to failure probability of individual corrosion sites.