Maintenance interval decision models for a system with failure interaction

•A system is composed of n units connected in series, any unit fails would cause damages to other units.•We propose two different cases about failure interactions.•We present a periodical maintenance cost model for the multi-unit systems with failure interactions.•The result shows that failure interactions will shorten system maintenance interval.

Based on the three types of failure interactions, two periodical maintenance cost models were presented for a two-state series system and a three-state series system respectively, which all subjected to failure interactions between units. Consider any unit fails would cause damages to other units. The failure interaction influences included instantaneous damages and continuous damages between units. The result indicated that failure interactions will shorten system preventive maintenance interval, if the preventive maintenance strategy is based on the cost.