生物质平模成型过程中力特性与数值模拟分析

Mechanical properties and numerical simulation analysis of the forming process for biomass plane-die briquetting machine

应用有限体积元方法对生物质成型过程的力学特性进行分析,建立力学特性模型,并应用ANSYS有限元分析软件,对成型过程进行了数值模拟分析。通过流变特性分析,物料成型过程可分为致密、成型、保型和挤出4个阶段。成型段物料外层和内层等效应力基本相等,等效应变近似线性变化,该阶段物料主要以弹性变形为主。保型段物料应力和应变变化复杂,该段物料发生由弹性变形向塑性变形的演变。挤出段颗粒受到残余内应力作用,内外层物料的应变出现不规则的变化趋势。成型段模孔壁的接触应力最大,且基本保持不变;保型段物料弹性变形减少,接触应力逐渐降低。文章建立的力特性模型和数值模拟试验取得的结果可为成型参数控制和平模设备结构优化提供参考。

The biomass mechanical properties in the pellet forming process were analyzed by the finite volume element method and the mathematical model was set up. The process numerical simulation tests were carried out by the ANSYS software. The pelleting process could be divided into closing, molding, shape-preserving and extrusion four stages through the analysis of the material rheologieal properties. In molding stage, the equivalent stress of outer and inner place was almost equal and the equivalent strain approximated linear variation which the material based mainly on the elastic deformation. In shape-preserving stage, the equivalent stress and strain varied complicatedly which the evolution of material in this phase from the elastic deformation to the plastic deformation. The equivalent stress and strain in the extruding zone appeared irregular variation because of the residual stress. The contact stress of the die hole reached the maximum in the forming area and reduced gradually due to the elastic deformation reducing in the whole shape-preserving area. The above mathematical properties model and numerical simulation conclusions provided reference for the process parameter control and the plane-die structural optimization.