增材制造金属跨尺度冲击损伤与疲劳研究OA

The catapults,arresting hooks,weapon racks,and related structures of carrier-based aircraft are subjected to multiple impact loads during repetitive takeoff and landing processes.This leads to a failure mechanism that involves both impact damage and fatigue damage occurring simultaneously,thereby threatening the safety of the carrier-based aircraft,and even the aircraft carrier itself.Based on the Johnson-Cook dynamic constitutive model and the Lemaitre impact damage model,this paper further incorporates the strain gradient theory.A novel cross-scale impact damage constitutive theory is consequently developed.From this theory,an impact fatigue life prediction model is then derived.Additively manufactured 18Ni300 high-strength steel(MS1)was fabricated and characterized,with its constitutive parameters calibrated.To validate the proposed constitutive relationships and fatigue life prediction model,a cross-scale impact damage finite element model was established.This finite element model was employed to investigate the mechanical response and damage evolution of a U-notch specimens under repeated impact loading,and the cross-scale impact fatigue life prediction model was utilized to estimate their fatigue life.The results demonstrate that the material exhibits an approximately power-law relationship between impact fatigue life and plastic strain under cyclic impacts.The proposed model,which accounts for the material size effect,effectively captures this characteristic.