Determination of the Failure Susceptibility of a Flat Die Used in Biomass Pelletizing Machines by Means of FEA-Based Design Exploration

Abstract

This paper focuses on a design analysis of a flat die used in an agricultural biomass pelletizing machine by considering its high-pressure loading failure susceptibility. The pellet die is one of the key elements in a pelletizing machine, and the strength of the die plate has an important role on the pellet’s quality and producibility. In fact, higher compression ratio (CR—the ratio of effective length and the internal (press channel) diameter of a die orifice/hole) will provide denser pellets which is a desired phenomenon, however, if the compression pressure is too high or CR is not determined to compensate high pressures, the raw material may block the die and the die may experience deformation failure due to overloading. If the desire is to make high-quality pellets with no die failure, optimum flat die hole/orifice design parameters should be used which can provide the best CR for a specific compression pressure. This is the core motivation of this research. In this study, finite element analysis (FEA)-based design exploration has been utilized for a sample single hole flat die with various die geometry parameters against various compression pressure values. Following the FEA design exploration undertaken, a response surface analysis (RSA) was carried out and then estimation models (empirical equations), which could be used to calculate parameters of the die hole/orifice against applied compression pressure and failure susceptibility based on structural stress and deformation, was described. The results gained from the RSA have indicated that the estimation models have high R2 values (higher than 98%) which could be used for adequately predicting failure susceptibility indicators. In addition to this, FEM-based simulation printouts have provided useful stress distribution visuals on the die against different compression pressure values. Most especially, the study has highlighted that a detailed structural optimization study may be scheduled in order to obtain die geometry design parameters with a focus on the failure susceptibility.