1 Introduction Damping bolts with WC–Co wear-resistant coatings serve as critical connecting components in helicopter rotor systems. The coatings help suppress fretting wear and enhance wear resistance [1, 2]. However, under complex service loads, the bolts are prone to cracking at the bolt shank, which is different from the fatigue failure site found at the bolt head or thread region [3]. Fretting fatigue assumptions on this issue fail to accurately predict the fatigue initiation site [4, 5].
