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水射流喷丸强化残余应力场的有限元模拟 总被引:4,自引:2,他引:2
针对水射流的高湍动特性与受喷靶体材料复杂的弹塑性形变行为,提供一种水射流喷丸强化残余应力场的有限元分析方法.基于准静态压力分布和非线性轴对称面分布载荷,采用多线性各向同性强化的Mises率不相关弹塑性模型,应用Prandtl-Reuss塑性增量理论及增量初应力法,利用线性斜坡载荷加载制度,运用ANSYS有限元软件模拟不同压力作用下水射流喷丸在2A11铝合金材料表层产生的残余应力场,获得残余应力场的分布规律及残余应力沿层深和径向的变化规律,指出残余应力沿层深分为残余压应力区和残余拉应力区,沿径向分为第Ⅰ残余压应力区、残余拉应力区和第Ⅱ残余压应力区,得到表面残余压应力、表层最大残余压应力、残余压应力层深度随着喷丸压力的增加而增大.为验证有限元模拟的正确性,对喷丸表面残余压应力进行试验验证,结果表明,有限元法计算的表面残余压应力值与试验数据近似吻合. 相似文献
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针对前混合水射流的液固湍动特性与喷丸过程多重非线性耦合作用行为,提供一种射流喷丸强化残余应力场的有限元分析法。采用液固两相流动理论与计算流体动力学方法分析喷嘴内流特性,建立射流多弹丸喷丸模型;基于弹丸速度冲击载荷加载制度,利用多线性各向同性强化弹塑性模型,应用动态接触对称罚函数法,运用ABAQUS软件模拟不同弹丸数量作用下射流喷丸在45钢材料表层产生的残余应力场,获得残余应力场的分布规律及残余应力沿深度的变化规律;得出射流喷嘴内流呈均质流流型,不同弹丸数量射流喷丸在材料表层产生的径向残余应力沿深度的变化规律相同,但在材料表面产生的径向残余压应力值受喷丸模型影响较大,对弹丸分三层排列、相邻弹丸之间径向和周向中心距离均为弹丸半径的多弹丸喷丸模型,数值模拟获得的表面径向残余压应力值与射流喷丸试验数据基本吻合。 相似文献
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杜赓林 《机械制造与自动化》1995,(5)
控制喷丸不仅是一种强化金属的重要手段,而且是一种经济、节能、用途广阔又急待提倡的工艺方法。如图所示、这种工艺是用普通钢丸或不锈钢丸,玻璃丸或陶瓷丸高速喷射被处理件,通过控制喷丸材质、形状、尺寸与硬度,以及射流强度,角度与均匀性等参数,获得预期的应变强化层深度及其内的残余压应力分布状态。强化层深度决定于工艺要求,对于圆筒状零件,有的规定:单向喷丸时,残余压应力层深度为壁厚的10%;双向喷丸时,为壁厚的5%。有的报道.残余压应力层的深度范围为0.25~2.5mm。 相似文献
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焊接不可避免产生残余应力,对结构完整性造成很大影响。提出利用高压水射流喷丸技术降低焊接残余应力,并利用有限元法进行计算模拟。分别开发了模拟焊接的移动双椭球热源子程序及模拟高压水射流喷丸的移动压力载荷子程序,得到了经高压水射流喷丸处理前后焊接残余应力分布的变化规律。计算结果表明,经高压水射流喷丸处理后,焊缝和热影响区存在的焊态残余应力得到降低,在焊缝区已经产生压缩应力。证明高压水射流喷丸具有降低焊接残余应力的效果。 相似文献
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对AISI304不锈钢氩弧焊缝表面进行了喷丸处理,通过光学显微镜和扫描电镜对材料表面及断口的微观组织进行了观察,用X射线应力衍射仪测试了喷丸处理前后试样的残余应力,并进行了在NaCl水溶液中的应力腐蚀试验。结果表明:喷丸处理前,AISI304不锈钢焊缝在NaCl溶液中具有明显的应力腐蚀开裂敏感性,应力腐蚀裂纹断口表现为脆性断裂,属于穿晶型裂纹;喷丸处理后表面获得了组织细化的硬化层,残余压应力有极大提高,有效地降低了不锈钢焊缝的应力腐蚀开裂倾向。 相似文献
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Wang Jianming Liu Feihong Yu Feng Zhang Gang 《The International Journal of Advanced Manufacturing Technology》2011,56(5-8):571-578
Shot peening is a complex surface-treating process which is usually employed to improve the fatigue strength of metallic part or members. In dealing with shot peening simulation, existing literatures apply finite element method (FEM) to establish only a single shot or several shots models, thus the effect of a mass of shots impacting repeatedly and the interaction among adjacent shots are ignored. To overcome these defects of FEM models, smoothed particle hydrodynamics (SPH) coupled FEM modeling is presented, in which the shots are modeled by SPH particles and the target material is modeled by finite elements. Contact algorithm is used to simulate the interaction between shots and target. Utilizing this model, material model for shots is established, the relationships between compressive residual stress and peening frequencies, coverage, and velocities are analyzed. Steady compressive residual stress can be gotten by multiple peening; higher coverage can improve the compressive residual stress; faster velocities can induce greater and deeper maximum residual stress in target subsurface. The simulation results agree well with the existing experimental data. The study will not only provide a new powerful tool for the simulation of shot peening process, but also be benefit to optimize the operating parameters. 相似文献
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Junfeng Xiang Siqin Pang Lijing Xie Guanhua Cheng Ruo Liang Feinong Gao Long Bai 《The International Journal of Advanced Manufacturing Technology》2018,97(5-8):1673-1685
This paper proposed a numerically low-cost 3D FE modeling method for multi-shot shot peening. The low computation cost and high prediction accuracy of shot peening are realized at the same time by the incorporation of random multi-shot with defined spacing between the adjacent simultaneously impinging shots, periodicity, and coverage rate of 100%. With this modeling method, one-step and dual-step multi-shot peening of 34CrNiMo6 steel target is modeled and the produced residual stress is predicted. In order to make the predicted residual stress depth profile more comparable with the measured one by XRD method, the redistribution of residual stress due to the layer removal by electrochemical polishing is simulated using Model Change technique. And the comparison between the prediction and experiment indicates that this improved 3D periodic FE modeling of multi-shot impingement provides very accurate simulation models for one-step and dual-step shot peening. It can substitute for the costly and time-consuming optimization experiments of the shot peening process, especially the multi-step shot peening process. Finally, the evolution of residual stress depth profile in dual-step shot peening process is investigated by using the simulation model and a variation of residual stress towards a more uniform distribution on the finished surface taking place in the second step is discovered by RMS analysis. 相似文献
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作为机械表面强化技术之一,喷丸强化使工件表层发生形变硬化,引入较高的残余压应力,减少了疲劳应力作用下微裂纹的萌生并抑制其扩展,从而显著提高零件的抗疲劳断裂和抗应力腐蚀开裂的能力。基于喷丸残余应力解析计算模型,从余弦函数模型、接触应力模型和球腔膨胀模型三个方面介绍喷丸强化残余应力的产生,进而对喷丸残余应力的仿真预测及影响规律进行论述。为了提高试件疲劳强度而引入的残余压应力会带来影响形位精度的变形,基于此阐述了喷丸残余应力对疲劳性能的影响及其在疲劳过程中的演化,同时论述了喷丸残余应力变形预测及控制的研究现状,最后对喷丸残余应力未来的研究内容与发展方向进行展望。 相似文献
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Z. Y. Liu C. Huang Y. Zhao Y. B. Guo 《The International Journal of Advanced Manufacturing Technology》2017,93(5-8):1669-1683
The applications of functional ceramics are significantly limited by the brittleness and low reliability. Recent studies have shown that compressive residual stress can be created in ceramics by shot peening, which improves the contact strength and fatigue of ceramic components. However, the formation mechanism of residuals stress in shot peening is yet to understand. In this study, a pressure-dependent plasticity model has been incorporated into a finite element simulation model of shot peening to understand the process mechanism underpinning the residual stress formation. Since shot velocity is the key process parameter to dominate the impact energy which determines the deformation state of the peened surface and the resultant residual stress, a new kinematic model of shots has also been developed by incorporating air drag and travel distance inside and outside the peening nozzle. The results have shown that the shot velocity model can be used to predict shot velocity. The experiment-based model may help understand the process mechanism underpinning the residual stress formation. 相似文献
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Numerical Calculation and Experimental Research on Residual Stresses in Precipitation-hardening Layer of NAK80 Steel for Shot Peening 总被引:1,自引:1,他引:0
MIAO Hong ZUO Dunwen WANG Min ZHANG Ruihong WANG Hongfeng Jiangsu Key Laboratory of Precision Micro-Manufacturing Technology Nanjing University of Aeronautics Astronautics Nanjing China College of Mechanical Engineering Yangzhou University Yangzhou China 《机械工程学报(英文版)》2011,(3):439-445
Shot peening can improve fatigue strength of materials by creating compressive residual stress field in their surface layers,and offers a protection against crack initiation and propagation,corrosion,etc.And fatigue fracture and stress corrosion cracking of NAK80 steel parts are improved effectively.Currently there lacks in-depth research in which the beneficial effect of the residual stress may be offset by the surface damage associated with shot peening,especially in terms of the research on the effective control of shot peening intensity.In order to obtain the surface residual stress field of NAK80 steel after shot peening,the samples are shot peened by pneumatic shot peening machine with different rules.The residual stress in the precipitation-hardening layer of NAK80 steel is measured before and after a shot peening treatment by X-ray diffraction method.In order to obtain true residual stress field,integral compensation method is used to correct results.By setting up analytical model of the residual stress in the process of shot peening,the surface residual stress is calculated after shot peening,and mentioning the reason of errors occurred between calculated and experimental residual stresses,which is mainly caused by the measurement error of the shoot arc height.At the same time,micro hardness,microstructure and roughness in the precipitation-hardening layer of NAK80 steel before and after shot peening were measured and surveyed in order to obtain the relation between shot peening strength and surface quality in the precipitation-hardening layer.The results show that the surface quality of NAK80 steel is significantly improved by shot peening process.The over peening effect is produced when the shot peening intensity is too high,it is disadvantageous to improve sample’s surface integrity,and leading to reduce the fatigue life.When arc high value of optimal shot peening is 0.40 mm,the surface quality is the best,and the depth of residual stress in the precipitation-hardening layer reaches to about 450 μm.Numerical calculation is very useful to define the process parameters when a specific residual stress profile is intended,either to quantify the benefits on a specific property like fatigue life or to help on modeling a forming process like shot peen forming.In particular,the proposed parameter optimization in the progress of shot peening and effective control of the surface texture provide new rules for the quantitative evaluations of shot peening surface modification of NAK80 steel. 相似文献
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为有效控制2E12铝合金的晶间腐蚀失效行为,采用浸泡腐蚀试验、金相分析技术、扫描电镜分析技术和X射线衍射分析技术等研究了喷丸强化和应力因素对2E12-T3铝合金晶间腐蚀行为的影响规律,并探讨了作用机理。研究结果表明:2E12-T3铝合金具有很高的晶间腐蚀敏感性,拉应力会明显增强其敏感程度,而压应力则会降低其敏感性。采用合理的喷丸强化处理(喷丸强度取0.15 mmN,覆盖率取100%)能够明显降低2E12-T3铝合金的晶间腐蚀敏感性,因为喷丸在铝合金表面引入合理分布的残余压应力,同时使表层晶粒细化,铝合金的电化学活性降低,晶间的选择性腐蚀得到有效控制。然而,喷丸强度过高或喷丸覆盖率过大时,铝合金表面会存在较严重的脱层等损伤性破坏,反而会使2E12-T3铝合金的晶间腐蚀敏感程度提高。 相似文献
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Jongbin Im Ramana V. Grandhi Younghee Ro 《Journal of Mechanical Science and Technology》2012,26(12):3943-3952
Laser peening (LP) induces high-magnitude compressive residual stresses in a small region of a component. The compressive residual stresses cause plastic deformation that is resistant to fatigue fracture. Fatigue cracks are generally nucleated at critical areas, and LP is applied for those regions so as to delay the crack initiation. Many critical regions are located on the edge of the curved portion of structures because of stress concentration effects. Several investigations that are available for straight components may not give meaningful guidelines for peening curved components. Therefore, in this paper, we investigate residual stress behaviors induced by LP along the edge of curved models. Three curved models that have different curvatures are investigated for peening performance. Two types of peening configurations, which are simultaneous corner shot and sequential corner shots, are considered in order to obtain compressive residual stresses along an edge. LP simulations of multiple shots are performed to identify overlapping effects on the edge portion of a curved model. In addition, the uncertainty calculation of residual stress induced by LP considering laser pulse duration is performed. 相似文献
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Junji Sakamoto Yong-Sung Lee Seong-Kyun Cheong 《Journal of Mechanical Science and Technology》2014,28(9):3555-3560
Shot peening is an effective and economical technique for improving the fatigue strength of metallic components by inducing compressive residual stress and hardening the layer near the surface. The effect is generally evaluated by main two parameters: coverage and peening intensity. However, the valuable coverage for improving the fatigue strength depends on the shape of the target material. In this study, the effect of coverage on fatigue limit in round bar of annealed medium carbon steel was experimentally studied. The fatigue limits for shot peened round bar specimens with 140–2300% coverage increased 14–25% by comparing those for non-peened round bar specimens. The valuable range of coverage was 280–60% in the used material and shot peening condition for improving the fatigue limit in short time. The result indicates that the valuable coverage of the round bar material is higher than full coverage to improve the fatigue limit of the material due to the effect of incident angle on round bar, even though the degree depends on the materials and shot peening conditions. 相似文献
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Baskaran Bhuvaraghan Sivakumar M. Srinivasan 《International Journal of Mechanical Sciences》2011,53(6):417-424
Almen intensity is used in the shot peening industry as a standard measure of the residual stress during shot peening and it is employed to ensure the quality of the peening of identical parts. However, relating the intensity to the residual stresses in the strip needs to be established with confidence by realistic simulations. An improved FEM-based approach that simulates the actual process of Almen strip peening is presented in this paper. This approach has some unique features such as employing randomly located shots impacting on a slice of Almen strip and the inclusion of strain-rate dependent target material properties and the lateral deflection of the strip for improved accuracy. The intensity, the corresponding residual stresses and roughness match well with available experimental results. Further, it is shown in this study that the Almen intensity can be correlated well with the residual compressive stresses of the target material using a parameter that depends on the relative dynamic yield strength of the target material. 相似文献
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Masanori Seki Masahiro Fujii Yuji Kobayashi Masaaki Sato Akira Yoshida 《Journal of Mechanical Science and Technology》2010,24(1):141-144
To investigate the influence of shot peening on the surface durability of powder-forged rollers, the case-hardened powder-forged
rollers with a forging density of 7.5 g/cm3 treated by the single shot peening and the double shot peening were fatigue-tested under a sliding-rolling contact condition.
The surface roughness, the surface hardness and the surface compressive residual stress of the rollers were increased by the
shot peening. In addition, the pores near the roller surface were deformed by the shot peening. The failure mode of all the
test rollers was spalling due to subsurface cracking. The fatigue lives of all the test rollers were improved by the shot
peening, and that of the test roller S08, which was shot-peened with the hardest steel shots in this experimental range, was
especially improved. The surface durability of the test roller S08 was also most improved by the shot peening. Cracks became
difficult to occur and propagate under the roller surface since the pores near the roller surface were deformed by the stronger
shot peening. In this study, double shot peening, which generally restrains the increase in surface roughness, was not particularly
effective for the improvement in the surface durability of the powder-forged rollers, because the influence of tangential
force on fatigue was not always great in a case of subsurface cracking. 相似文献