基于梯度降温的叠层制备热残余解析解

Thermal residual solutions to laminated object manufacturing with gradient cooling

叠层制备工件因高温制备环境易出现热残余应力和变形。实际制备工艺因制备时间差会产生降温梯度,充分考虑成型过程中沿厚度方向形成的温度梯度,建立了热残余变形和应力的解析解。根据具体的叠层工艺,采用不同的梯度降温模式。算例表明,梯度降温会造成显著的热残余现象;讨论了4种梯度降温模式对热残余程度的影响;合理解释了工件因降温梯度会产生明显的弯曲变形;揭示了弯曲变形实际上是工件降低残余应力的调节机制,以增大弯曲变形为代价来降低残余应力。研究结果为叠层制备工艺优化提供了可靠的理论依据。

Laminated object manufacturing results in thermal residual stresses and deformation due to its high temperature tech- niques. Cooling gradients occurs due to the time differences in manufacturing processes. Considering the temperature gradients through thickness in manufacturing processes, the analytical solutions of thermal residual stresses and deformations are built. There are several cooling gradient models due to different manufacturing techniques. It is shown in numerical examples that cool- ing gradients resuh in thermal residual phenomenon through thickness. The effects of cooling gradient models on thermal residual stresses are discussed. The model can reasonably explain the bending deformation due to the cooling gradients in a workpieces. Bending deformation is actually a self-regulation mechanism to reduce residual stresses in the workpiece, which means that in- creasing the bending deformation can reduce the thermal residual stresses. This work provides a reliable theoretical basis for the optimization of laminated object manufacturing.