Our group has on-going research to develop new in-situ and ASTM standard testing methods for measuring flow, shear and compression loading of biomass particles (corn, soybean, rice, and wheat straw) and applied Design of Experiment (DOE) and optimization technique for Discrete Element Method (DEM) simulation of crop engaging equipment in grain handling, mechanical and pneumatic crop separation systems. With the DEM particle models for the various biomass particles, relatively accurate (less than ten per cent relative error) prediction of discharge mass flow rates from hopper orifice (corn, rice, and soybean), impact forces on combine grain yield system systems for varying corn moisture content, and compression pressure of wheat straw in confined chambers. Applying physics-based calibrated particle models from our research have enabled accelerated simulation-based design analysis of industry-scale grain harvesting system and optimized equipment designs.