【摘要】 目的：针对薄壁钛合金（Ti6Al4V）构件表面强化效率与效果难以兼顾，以及关键疲劳区域侧铣加工强化研究不足的问题，本文提出椭圆超声喷丸侧铣（UPSM）及双程超声喷丸侧铣（TUPSM）新方法，旨在实现加工与强化同步进行，以探究其表面强化机理与疲劳性能提升效果。创新点：1.提出适用于薄壁结构关键疲劳区域侧铣加工的UPSM方法，并首创TUPSM工艺，实现加工与强化的高效集成；2.通过运动学分析与二维切削仿真，揭示UPSM中刀具后刀面熨压效应和切削刃冲击效应的双重表面强化机理，以及TUPSM的累积强化机制；3.系统阐明超声振幅和加工循环次数对表面形貌、残余应力、亚表层塑性变形层及疲劳性能的调控作用。方法：1.建立UPSM刀具运动轨迹模型，并分析其切削与强化过程（图1～3）;2.采用ABAQUS软件进行二维有限元切削仿真，并对比分析常规切削（CM）、UPSM及TUPSM过程中的应力演化、塑性变形（PEEQ）和残余应力（S11）的分布特征，以揭示强化机理（图4、5、S1和S2）;3.通过实验研究，对比分析不同工艺下的切屑形态、表面形貌、表面粗糙度、表面残余应力及亚表层塑性变形层（图9～13）;4.进行高周疲劳寿命测试，并分析疲劳源位置、裂纹扩展路径及疲劳条带特征，以揭示疲劳性能提升机制（图14～17和S3）。结论：1. UPSM产生带有振动纹理的卷曲切屑，且振幅增至8μm时出现局部断屑特征；TUPSM产生较为细小的破碎切屑。2.相较于CM,UPSM显著减少表面划痕、鳞片等缺陷。3. UPSM通过刀具后刀面熨压和切削刃冲击效应实现显著的表面强化；在8μm振幅下，表面残余压应力和亚表层塑性变形层厚度较CM分别提升47.4%和91.5%;TUPSM通过叠加二次熨压和冲击效应，进一步强化表面，且残余应力较CM提升55.5%。4. UPSM显著提升试件疲劳寿命，并使疲劳源萌生位置从表面转移至亚表面甚至内部；在8μm振幅下，UPSM和TUPSM的疲劳寿命分别达到CM的3.38倍和3.76倍。5. UPSM和TUPSM被证明是一种有前景的钛合金强化技术，可有效提升薄壁构件的疲劳性能，同时实现精密加工。更多还原

【Abstract】 Ti6Al4V alloy is critical for thin-walled aerospace components, yet conventional methods for its surface enhancement struggle to balance efficiency and precision. While ultrasonic vibration milling has been demonstrated to improve fatigue performance, its strengthening mechanism requires further investigation. Additionally, its application in fatigue-critical side milling remains underexplored. To address this gap, we introduce the method of ultrasonic peening side milling(UPSM), which integrates elliptical vibration into side milling to achieve simultaneous machining and surface strengthening. Theoretical and finite element analyses are performed to elucidate the mechanisms of residual stress generation and plastic deformation in UPSM and two-pass UPSM(TUPSM). Our experimental results demonstrate that the UPSM method reduces surface defects. At a vibration amplitude of 8 μm, UPSM increases the surface residual compressive stress by 47.4% and the thickness of subsurface plastic deformation layer by 91.5% as compared to conventional milling(CM). TUPSM amplifies these effects, achieving a 55.5% increase in residual compressive stress. Fatigue tests reveal 3.38-fold(for UPSM) and 3.76-fold(for TUPSM) improvement in fatigue life over CM, a phenomenon which is attributed to the subsurface crack initiation and grain refinement induced by ultrasonic ironing and impact effects. This work establishes UPSM as an integrated and cost-effective solution for enhancing fatigue performance in thinwalled Ti6Al4V components, overcoming the limitations of conventional methods and advancing between precision machining and strengthening treatments.更多还原