熔融沉积过程中单向扫描路径对制件残余应力的影响

Influence of single-direction deposition direction on residual stress of fused deposition modelled parts

熔融沉积成型(FDM)是将材料从熔融态转化为固态的逐层堆积过程,同时存在着热量的输入和传导,而温度变化会造成FDM制件残余应力的产生.残余应力作为附加载荷会直接影响产品表面质量以及几何尺寸的精度,还会造成产品发生翘曲变形以及一些内在缺陷.文中利用"单元生死"技术并基于ANSYS参数化编程语言(APDL)动态模拟单向FDM制件在常规和改进型两种不同扫描路径下的温度场,并继而分析在温度场作用下制件内残余应力的分布及其随平行于丝材轴线扫描方向(纵向)的演变过程.数值模拟和实验验证的结果均表明,通过改进型扫描路径打印出来的制件,残余应力的最大值下降很多,分布也更合理,较多区域只有3次应力波动,有力证明了该种扫描路径的优越性.

The fused deposition modeling(FDM)is a process turning the material from the molten state into a solid layer by layer deposition.During the processing,heat input and conduction are unavoidable,and the variation of temperature will result in residual stress of the FDM sample.Residual stress as an additional load will directly affect the surface quality of the product and the accuracy of geometric dimension,and also cause warpage and some inherent defects.In this paper,the"unit life and death"technology and the ANSYS parametric programming language(APDL)are used to dynamically simulate the temperature field of the unidirectional FDM article under two different conventional and improved scan paths,and then we analyze the distribution of the residual stress in the workpiece under the action of the temperature field and its evolution in the scanning direction(longitudinal)parallel to the axis of the wire.Both numerical simulations and experimental verification show that the maximum residual stress decreases greatly,the distribution is more reasonable for parts printed by the improved scan path,and there are only three stress fluctuations in some areas,which strongly proves the superiority of the scanning path.