Overview of finite elements simulation of temperature profile to estimate properties of materials 3D-printed by laser powder-bed fusion

Laser powder bed fusion(LPBF),like many other additive manufacturing techniques,offers flexibility in design expected to become a disruption to the manufacturing industry.The current cost of LPBF process does not favor a try-anderror way of research,which makes modelling and simulation a field of superior importance in that area of engineering.In this work,various methods used to overcome challenges in modeling at different levels of approximation of LPBF process are reviewed.Recent efforts made towards a reliable and computationally effective model to simulate LPBF process using finite element(FE)codes are presented.A combination of ray-tracing technique,the solution of the radiation transfer equation and absorption measurements has been used to establish an analytical equation,which gives a more accurate approximation of laser energy deposition in powder-substrate configuration.When this new analytical energy deposition model is used in in FE simulation,with other physics carefully set,it enables us to get reliable cooling curves and melt track morphology that agree well with experimental observations.The use of more computationally effective approximation,without explicit topological changes,allows to simulate wider geometries and longer scanning time leading to many applications in real engineering world.Different applications are herein presented including:prediction of printing quality through the simulated overlapping of consecutive melt tracks,simulation of LPBF of a mixture of materials and estimation of martensite inclusion in printed steel.     

电子束辐照处理模拟甲苯废气的实验

目前治理低浓度甲苯废气的传统方法还存在很多问题，还需研发新的治理技术，为此，进行了电子束辐照处理甲苯的动态实验。     

扩展的Jacobi椭圆函数展开法和Zakharov方程组的新的精确周期解

对Jacobi椭圆函数展开法进行了扩展，且利用这一方法求出了Zakharov方程组的一系列新的精确周期解，在极限情况下可得到相应的孤波解，补充了前面研究的结果. 关键词： Jacobi椭圆函数展开法 非线性发展方程 精确解 周期解     

微形大孔径鱼眼车载镜头光学设计

将典型反远摄镜头设计方法与PWC法相结合,从理论模型出发搭建初始结构,借助光学设计软件ZEMAX辅助设计.得到一款工作波段436 nm、486 nm、546 nm、587 nm、656 nm,F#1.5,全视场角160°,光学总长18.5 mm,可应用于车载后视系统的镜头,比市场上现有产品指标有明显提升,镜头高低温性能...     

一种测试小分子迁移的新方法

针对高聚物材料中小分子的迁移现象,结合数字图像处理技术,提出了一种基于钠光和斐索等厚原理的光学干涉法.介绍了系统测试原理,针对光学系统的设计作了详细的分析与计算;通过实验测试,设计的光学系统能够采集到清晰的干涉条纹,且满足测试精度要求,由条纹间距随时间的变化测出了丙酮和乙醇小分子迁移时高聚物折射率的变化规律为:丙酮小分...     

邻溴苯基—2—恶唑啉的合成研究

改进了邻溴苯基－２－恶唑的合成方法，使得Ｎ－（β羟乙基）－２－溴苯甲酰胺在氯化亚砚作用了缩合成恶唑啉的收率从４０％左右提高到８４％，并避免了使用ＮａＨ试剂，为芳基－２－恶唑啉的合成提供一条方便，经济的路线。     

离子束辅助沉积对类金刚石膜结构影响的计算机模拟

采用分子动力学(MD)模拟研究了离子束辅助沉积(1BAD)生长类金刚石(DLC)膜的物理过程.分 别选C₂分子和Ar离子作为沉积源和辅助沉积粒子.改变Ar的入射能量和到达比(A r／C)，研 究了它对DLC膜结构的影响.重点讨论了Ar辅助沉积引起表面原子的瞬间活性变化对薄膜结构 产生的影响.分析表明，由于Ar离子的轰击引起的能量和动量的传递，大大地增强了C原子在 表面的反冲动能及迁移概率，增加了合成薄膜的SP³键含量.研究结果和实验 观察一致，并从合成机理上给出了一些定量解释. 关键词： 类金刚石膜 离子束辅助沉积 分子动力学模拟