李广琪,朱刚贤,赵亮,王丽芳,石世宏.中空环形激光熔覆层温度场与应力场的数值模拟研究[J].表面技术,2020,49(7):319-328. LI Guang-qi,ZHU Gang-xian,ZHAO Liang,WANG Li-fang,SHI Shi-hong.Numerical Simulation on Temperature Field and Stress Field of Cladding Layer by Hollow-Ring Laser[J].Surface Technology,2020,49(7):319-328 |
中空环形激光熔覆层温度场与应力场的数值模拟研究 |
Numerical Simulation on Temperature Field and Stress Field of Cladding Layer by Hollow-Ring Laser |
投稿时间:2019-11-20 修订日期:2020-07-20 |
DOI:10.16490/j.cnki.issn.1001-3660.2020.07.040 |
中文关键词: 中空环形激光 残余应力 数值模拟 温度场 应力演化 实验测定 |
英文关键词:hollow ring laser residual stress numerical simulation temperature field thermal stress evolution experimental determination |
基金项目:国家重点研发计划(2016YFB1100300) |
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Author | Institution |
LI Guang-qi | a.School of Mechanical and Electrical Engineering, Soochow University, Suzhou 215021, China |
ZHU Gang-xian | a.School of Mechanical and Electrical Engineering, Soochow University, Suzhou 215021, China |
ZHAO Liang | a.School of Mechanical and Electrical Engineering, Soochow University, Suzhou 215021, China |
WANG Li-fang | b.Engineering Training Center, Soochow University, Suzhou 215021, China |
SHI Shi-hong | a.School of Mechanical and Electrical Engineering, Soochow University, Suzhou 215021, China |
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中文摘要: |
目的 研究基于“光束中空、光内送粉”工艺下中空环形激光熔覆层温度场分布规律、应力演化过程及沿熔覆层深度方向上的残余应力分布,为调控或降低光内送粉激光熔覆层残余应力提供参考。方法 采用ANSYS软件APDL语言建立单道熔覆层物理模型,利用生死单元法模拟激光加载,从而得到温度场结果,在此基础上进行热力耦合,分析熔覆层内应力演化过程,在熔覆层深度方向上建立路径,得到沿路径方向上的残余应力分布结果,最后进行实验测定。结果 当采用中空环形激光束加载时,光斑温度分布呈“马鞍形”,熔覆层横切面上温度分布形状呈对称的“W”形,两侧温度高,中间温度低,熔覆层上表面扫描路径上的节点在扫描过程中都会经历两次温度峰值,且第二次温度峰值要高于第一次。热应力随着扫描过程进行而不断变化,由起初产生的熔覆层压应力逐渐转化为拉应力。沿扫描方向上的残余应力值最大,可达到273 MPa。熔覆层深度方向沿扫描方向上的残余应力值在上表面位置有最大值235 MPa,熔覆层与基材接合面处有最小值185 MPa。最后结合实验测定,数值计算与实验结果一致。结论 中空环形激光光斑“马鞍形”式的能量分布使得熔覆层温度分布更为均匀,可有效降低温度梯度。环形光斑后半环高温区域的重熔作用有利于能量的再分配,有利于减缓应力集中。熔覆层深度方向沿激光扫描方向上的残余应力分布,随着深度的增加而逐渐减小。 |
英文摘要: |
The work aims to study the distribution law of temperature field, stress evolution process and residual stress distribution along the cladding depth direction of hollow ring laser cladding layer based on the process of "hollow beam and inside-beam powder feeding" and provide guidance for regulating or reducing the residual stress of laser cladding layer. APDL language in ANSYS software was used to establish physical model of single cladding layer and simulate the laser loading to obtain the temperature field result by birth and death element. Based on this, the thermo-mechanical coupling was performed, the stress evolution process was analyzed and the path along the depth direction of the cladding layer was established, and the residual stress distribution results were obtained. Finally, the experimental determination was made. The spot temperature distribution was in “saddle” shape and the temperature distribution on the cross section of the cladding layer was in symmetric “W” shape when the hollow-ring laser beam was loaded. At the same time, the temperature of the cladding layer on both sides was high and the intermediate temperature was low. The nodes on the upper surface of cladding layer were heated twice during the laser scanning, and the second peak temperature was higher than the first time. The thermal stress changed continuously in the scanning process, which was transformed form compressive stress generated in the initial cladding process into tensile stress. The residual stress value along the scanning direction was the largest, which was up to 273 MPa, while the largest value at the upper surface was 235 MPa. The minimum value of the bonding surface between the cladding layer and the substrate was 185 MPa. Finally, the numerical calculation was consistent with the experimental results through the experimental determination. The "saddle-shaped" energy distribution of the hollow ring laser spot makes the temperature distribution of the cladding layer more uniform, which can effectively reduce the temperature gradient. The remelting effect of the high temperature region in the rear half of the ring spot facilitates the redistribution of energy and reduces stress concentration. The residual stress distribution in the depth direction of the cladding layer along the laser scanning direction gradually decreases with increasing depth. |
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