为了研究超声喷丸处理过程弹丸与构件之间弹塑性接触状态、应力场及表面状态分布规律，基于显式微粒离散函数的多弹丸撞击模型和Hertz-Mindlin （No Slip）碰撞接触力学定律，建立了弹丸冲击速度与恢复系数之间的模型。针对超声喷丸过程，建立DEM-FEM （离散元-有限元）耦合数值模型，建立ALE自适应网格模型，通过数值模拟研究恒定恢复系数与动态恢复系数对构件表面残余应力、残余应力层深度、表面宏观形貌的影响，恒定恢复系数增加的过程中，表面残余压应力、残余压应力层深度、表面粗糙度均增加，相比残余应力层深度与表面粗糙度，表面残余应力分布极值差低约12%，相比残余应力层深度内外端均值差值，表面残余应力与表面粗糙度差值低约9%~15%。结果表明，在恒定与动态恢复系数下，与残余压应力层深度相比，表面残余应力与表面宏观形貌更容易实现均匀性；与恒定恢复系数相比，动态恢复系数对构件表面引入的残余应力与试验结果误差均低于5%，预测更接近真实值。
To study the elasto-plastic contact state and stress field distribution between the projectile and the component during the ultrasonic shot peening process, the multi-projectile impact model based on the display particle dispersion function and the Hertz-Mindlin (No Slip) collision contact mechanics law is used. A model between the impact velocity of the projectile and the coefficient of restitution is established. According to the spherical cavity expansion model, the stress field under the collision of a single projectile is calculated. Aiming at the numerical model of ultrasonic shot peening, DEM-FEM coupling numerical model and ALE adaptive mesh model is established, and the effects of constant coefficient of restitution and dynamic coefficient of restitution on the surface residual stress, residual stress layer depth, and surface macroscopic morphology of the component surface are studied through numerical simulation. The constant recovery coefficient increased in the process, the surface compressive residual stress, the depth of the compressive residual stress and surface roughness are all increased. Compared with the depth of the residual stress layer and the surface roughness, the extreme value of the surface residual stress distribution is about 12% lower than the average value of the inner and outer ends of the residual stress layer depth. The difference between the surface residual stress and the surface roughness is about 9%-15% lower. The results show that under constant and dynamic coefficient of restitution, the surface residual stress and the surface macro morphology are easier to achieve uniformity, compared with the depth of the compressive residual stress layer. And compared with the constant coefficient of restitution, the residual stress introduced by the dynamic coefficient of restitution on the surface of the component and the test results are less than 5%, and the prediction is closer to the true value.
[1] 王彬文, 陈先民, 苏运来, 等. 中国航空工业疲劳与结构完整性研究进展与展望[J]. 航空学报, 2021, 42(5):524651. WANG B W, CHEN X M, SU Y L, et al. Research progress and prospect of fatigue and structural integrity for aeronautical industry in China[J]. Acta Aeronautica et Astronautica Sinica, 2021, 42(5):524651(in Chinese).
[2] 王业辉. TC4钛合金超声喷丸强化残余应力数值模拟分析[J]. 航空发动机, 2019, 45(3):58-64. WANG Y H. Numerical simulation analysis of residual stress in ultrasonic shot peening of TC4 titanium alloy[J]. Aeroengine, 2019, 45(3):58-64(in Chinese).
[3] BARLETTA M. Improvement of the fatigue behavior of stainless steel substrates by low pressure fluidized bed peening (FBP)[J]. Journal of Engineering Materials and Technology, 2011, 133(2):021018.
[4] COWLES B A. High cycle fatigue in aircraft gas turbines-an industry perspective[J]. International Journal of Fracture, 1996, 80(2-3):147-163.
[5] JAMES M N, NEWBY M, HATTINGGH D G, et al. Shot-peening of steam turbine blades:Residual stresses and their modification by fatigue cycling[J]. Procedia Engineering, 2010, 2(1):441-451.
[6] CIAVARELLA M, MACINA G. New results for the fretting-induced stress concentration on Hertzian and flat rounded contacts[J]. International Journal of Mechanical Sciences, 2003, 45(3):449-467.
[7] MURUGARATNAM K, UTILI S, PETRINIC N. A combined DEM-FEM numerical method for shot peening parameter optimisation[J]. Advances in Engineering Software, 2015, 79:13-26.
[8] NOUGUIER-LEHON C, ZARWEL M, DIVIANI C, et al. Surface impact analysis in shot peening process[J]. Wear, 2013, 302(1-2):1058-1063.
[9] ROUSSEAU T, HOC T, GILLES P, et al. Effect of bead quantity in ultrasonic shot peening:Surface analysis and numerical simulations[J]. Journal of Materials Processing Technology, 2015, 225:413-420.
[10] BADREDDINE J, ROUHAUD E, MICOULAUT M, et al. Simulation and experimental approach for shot velocity evaluation in ultrasonic shot peening[J]. Mécanique & Industries, 2011, 12(3):223-229.
[11] BADREDDINE J, MICOULAUT M, ROUHAUD E, et al. Effect of the confinement on the properties of ultrasonic vibrated granular gases[J]. Granular Matter, 2013, 15(3):367-376.
[12] MICOULAUT M, MECHKOV S, RETRAINT D, et al. Granular gases in mechanical engineering:on the origin of heterogeneous ultrasonic shot peening[J]. Granular Matter, 2007, 9(1-2):25-33.
[13] TU F B, DELBERGUE D, MIAO H Y, et al. A sequential DEM-FEM coupling method for shot peening simulation[J]. Surface and Coatings Technology, 2017, 319:200-212.
[14] THORNTON C. Theoretical background[M]//Granular Dynamics, Contact Mechanics and Particle System Simulations. Cham:Springer International Publishing, 2015:13-25.
[15] DAVIES R M. The Determination of static and dynamic yield stresses using a steel ball[J]. Proceedings of the Royal Society of London, 1949, 197(1050):416-432.
[16] THORNTON C. Coefficient of restitution for collinear collisions of elastic-perfectly plastic spheres[J]. Journal of Applied Mechanics, 1997, 64(2):383-386.
[17] BHUVARAGHAN B, SRINIVASAN S M, POTODAR Y, et al. SP modeling by combining DEM and FEM[C]//International Conference on Shot Peening. 2008, 10:131-42.
[18] GAO X L, JING X N, SUBHASH G. Two new expanding cavity models for indentation deformations of elastic strain-hardening materials[J]. International Journal of Solids and Structures, 2006, 43(7-8):2193-2208.
[19] KIRK D, ABYANEH M Y. Theoretical basis of shot peening coverage control[J]. Shot Peener, 1995, 9(2):28-30.
[20] KOUMI K E, NELIAS D, CHAISE T,et al. Modeling of the contact between a rigid indenter and a heterogeneous viscoelastic material[J]. Mechanics of Materials, 2014, 77:28-42.
[21] KAWANO S, KAWAGISHI A, SUEZONO N, et al. Development of ultrasonic shot peening technique for reactor components to improve structural integrity against stress corrosion cracking[C]//Proceedings of 17th International Conference on Nuclear Engineering, 2010:543-547.
[22] 杨天南, 林爽, 蔡晋. 超声喷丸激励振动幅值对TC4钛合金表面状态影响的仿真研究[J]. 航空精密制造技术, 2020, 56(4):14-18. YANG T N, LIN S, CAI J. Simulation study of effect excited vibration on ultrasonic shot peening surface state of TC4 titanium alloy[J]. Aviation Precision Manufacturing Technology, 2020, 56(4):14-18(in Chinese).
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