Extended life time calculation of the Straddle Carrier

The original specification of the straddle carrier accounted for a maximum of 630.000 load cycles which is equivalent to 52.500 operational hours. After moving more than a 1.000.000 containers a remaining fatigue life of the metal structure of the straddle carrier was advised. Because of its high center of gravity and the absence of shock absorbers the complicated driving dynamics was researched first. These dynamic loads were used as a basis for the remaining fatigue live calculations.

Because of the relatively low number of welded connections, only a small number of attention locations required NDT weld inspection (Non-Destructive Testing). Because of an absence of detectable cracks in these locations, regular inspection of these fatigue vulnerable spots was sufficient to increase the safe operational limit to 2.000.000 load cycles.