增材制造中金属粉末卡塞动力学离散元模拟研究

Discrete Element Simulation of Metal Powder Spreading in Additive Manufacturing

基于金属粉末的增材制造技术在航空航天、新能源和新材料等领域中得到快速应用,但其产品性能受制于铺粉过程形成的粉层质量。本文基于金属粉末中离散颗粒的真实物理和力学参数,采用离散元方法对刮刀铺粉过程进行了模拟和分析。结果表明,粉层中颗粒总体积与铺粉间隙成线性关系,且临界铺粉间隙为基于颗粒数量的D_(90)。同时,粉层沿铺粉方向容易出现空斑,空斑的数量随其长度呈指数递减的规律,且空斑大小与铺粉间隙密切相关。颗粒容易在铺粉间隙处发生卡塞行为,发生概率随持续时间增加而急剧降低,且持续时间长的卡塞行为对粉层中空斑的形成起着主导作用。颗粒卡塞瞬间会产生强烈的力链结构,并通过颗粒迸射过程而在粉层中产生空斑。

The use of Additive Manufacturing(AM) based on metal powder has been rapidly applied in the fields of aerospace, new energy and new materials, but its product performance is limited by the quality of the powder layer formed during the spreading process. Based on the realistic physical and mechanical properties of an individual particle in the metal powder, the blade spreading process in additive manufacturing is simulated in this work by discrete element method.The results show that the total volume of particles in the spread layer is linear to the spreading gap,and the critical spreading gap size is the number based D_(90). Meanwhile, empty patches could be found in the spread layer along the spreading direction, and the number of empty patches decreases with its length in an exponential law while the size of empty patches is sensitive to the gap size.Particle jamming could occur at the spreading gap, and its probability decreases sharply with the survival time. The jamming event with longer survival time has more effects on the formation of empty patches in the spread layer. During the survival period of particle jamming in the spreading direction, large force of the contact pair is generated, and then the empty patches in the spread layer is formed through the burst process of particles.