Fuzzy fault tree analysis of EVAC system based on improved SAM- FFTA with butterfly optimization algorithm

•Propose a fuzzy fault tree analysis method incorporating the butterfly algorithm for reliability analysis of systems.•Adjustment of the relaxation factor enables a more accurate calculation of the probability of failure of the bottom event.•The most important cause of failure of 3D elliptical vibration-assisted cutting systems is the uneven heating of the tool.•Provide reasonable measures to maintain the functional reliability of the system.