基于梯度降温的叠层制备热残余应力

发布时间：2018-08-27 19:20

【摘要】：针对叠层制备工艺的热残余问题,为消除传统的基于同步降温假设的理论解与实际热残余现象的差异,本文在充分考虑成形过程中沿长度和厚度方向形成的温度梯度的基础上,分别建立在层平面和厚度方向引起的热残余变形和应力的解析解,并根据不同叠层制备工艺,将降温梯度概括为同步降温、均等梯度降温、非均等梯度降温、瞬态降温的4种模式.算例表明,梯度降温会造成在层平面和厚度方向均产生热残余现象.讨论了4种梯度降温模式对热残余程度的影响,梯度越大影响越大;合理解释了同一种材料制备的工件也会因降温梯度而产生明显的弯曲变形;对于梯度材料,叠层制备顺序会显著影响热残余的程度.研究表明,梯度降温假设符合实际制备、工艺,更准确地揭示了叠层制备热残余现象产生的机理,优化制备工艺缩小降温梯度是解决热残余问题的有效途径.
[Abstract]:In order to eliminate the difference between the traditional theoretical solution based on synchronous cooling hypothesis and the actual thermal residual phenomenon, the temperature gradient along the direction of length and thickness in the forming process is fully considered in this paper. The analytical solutions of the thermal residual deformation and stress caused by the plane and thickness direction of the layer are established respectively. According to the different laminated preparation processes, the cooling gradient is summed up as synchronous cooling, uniform gradient cooling, uneven gradient cooling. Four modes of transient cooling. An example shows that gradient cooling will result in thermal residual phenomenon in both the plane and thickness direction of the layer. The influence of four gradient cooling modes on the thermal residual degree is discussed. The bigger the gradient is, the greater the influence is, and it is reasonable to explain that the workpiece prepared by the same material will also have obvious bending deformation due to the cooling gradient. The preparation order of the laminated layer has a significant effect on the degree of thermal residue. The results show that the hypothesis of gradient cooling is in line with the actual preparation and the process, which reveals the mechanism of the thermal residual phenomenon in laminated preparation more accurately. Optimizing the preparation process to reduce the cooling gradient is an effective way to solve the thermal residual problem.
【作者单位】：淮海工学院机械工程学院;
【基金】：江苏省重点学科资助项目(苏财教[2014]-98-96)
【分类号】：TH16

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