可燃毒物芯块成型过程的有限元模拟分析

Finite Element Simulation Analysis of the Forming Process of Burnable Absorber

采用MSC.Marc有限元模拟软件,研究分析可燃毒物的原料氢化锆粉压制成形过程中粉末的运动情况、应力的分布及规律,研究了粉末成型工艺对压制坯的密度及等效应力的影响。结果表明,压坯高度方向上的高密度区和高应力区均为靠近上模头附近的区域;在半径方向上,压坯的相对密度在压坯轴线r=0 mm上的变化幅度最小,而在圆柱表层r=7.1 mm上,压坯的密度分布最不均匀;压坯的等效应力在压坯轴线r=0 mm上呈先减小后增加的趋势,在上模头附近到达最大,在中间圆柱面r=3.5 mm,压坯两端的等效应力差异不大,中间部分最小,分布较为均匀,在圆柱表层r=7.1 mm,压坯的下模头附近最小,在上模头附近有最大值。压坯最佳的压制工艺参数为成型压力600 MPa、保压时间20 s。

MSC. MARC finite element simulation software was used to study and analyze the movement and stress distribution of raw material( ZrH powder) of burnable absorber in the forming process, and the influence of different forming processes on the density and equivalent stress distribution of the compaction was explored. The results show that the high density area and high stress area in the direction of compaction height are near the upper die head. In the radius direction, the variation range of the relative density of the compaction is the smallest at the axis r=0 mm, and the density distribution is the least uniform at the surface of the cylinder r=7.1 mm.The equivalent stress of compaction on the axis r=0 mm firstly reduce and then increase and reach maximum near the die head, in the middle cylinder r =3.5 mm, the difference of equivalent stress at the ends of the compaction is not big and in the middle is the smallest thus its distribution is uniform generally;in the cylindrical surface r =7.1 mm, the equivalent stress of the compaction is the minimum near the lower die head and the maximum near the upper die head. The best pressing process parameters of compaction are the forming pressure of 600 MPa and the holding time of 20 s.