应力超声滚压表面强化机理和抗疲劳性能研究

Study on Strengthening Mechanism and Anti-fatigue Performance of Stress Ultrasonic Rolling

从理论分析角度探讨了超声滚压与单轴拉伸弹性应力场耦合的基本原理,并通过有限元模拟和实验表征依次从数值仿真和实验角度对理论分析结果进行验证,从而发展了一种先进的表面机械强化新工艺—应力超声滚压,并将其成功应用于TiB_(2)/2024和TiB_(2)/7050铝基复合材料表面机械强化效果的增强和抗疲劳性能的提升。结果表明,相较于普通超声滚压,应力超声滚压对TiB_(2)/2024和TiB_(2)/7050铝基复合材料表层压缩残余应力峰值的提升可分别达到所施加单轴拉伸弹性应力水平的45%和70%,可将压缩残余应力影响层深度提升约100μm,从而将两种复合材料样品的疲劳极限在普通超声滚压强化的基础上分别进一步提升6%和5%。

The basic principle of coupling ultrasonic rolling with uniaxial tensile elastic stress field is discussed from the perspective of theoretical analysis,and the results of theoretical analysis are verified from the perspective of numerical simulation and experiment through finite element simulation and experimental characterization in turn.Thus,a new advanced surface mechanical strengthening process,stress ultrasonic rolling,is developed and successfully applied to enhance the surface mechanical strengthening effect and fatigue resistance of TiB_(2)/2024 and TiB_(2)/7050 aluminum matrix composites.Compared with ultrasonic rolling,the results showed that,after stress ultrasonic rolling,the peak compressive residual stresses in the surface layers of TiB_(2)/2024 and TiB_(2)/7050 aluminum matrix composites are increased by 45%and 70%of the applied uniaxial tensile elastic stress values,respectively,the depth of the layer affected by compressive residual stresses is increased by about 100μm,and the fatigue limits of the two composite samples were further increased by 6%and 5%,respectively.