Optimisation design and experimental analysis of rotary blade reinforcing ribs using DEM-FEM techniques

Abstract

This study addresses the prevalent issue of rotary blade fractures in tillage operations by designing a new type of reinforcing rib that mitigates neck force and alleviates stress concentration. Initially, utilising traditional design concepts, the side-plate reinforcing rib was segmented into units and analysed using ANSYS to develop an initial model. Evaluation indices such as specific strength structural efficiency and specific stiffness structural efficiency were employed to perform orthogonal optimisation of the rib dimensions, achieving optimal measurements of 72.9 mm in length, 15.7 mm in width, and 3.5 mm in thickness. These dimensions enhance the specific strength structural efficiency by 14.14% and the specific stiffness structural efficiency by 0.95% compared to the initial model. Further, the rib's mathematical model was refined and generalised by a curve-fitting method across different rotary blade models (IT series), followed by topological optimisation to fine-tune morphological features. This optimisation reduced the model's mass by 9.78% and improved efficiency metrics by 2.6% (strength) and 0.5% (stiffness). Comparative experiments using DEM-FEM coupled analysis were conducted on three optimised models to assess the redesigned blade's performance. The experiments evaluated key performance metrics such as neck force, maximum stress, fatigue life, and ultimate fracture stress. The results indicate that after two rounds of optimisation, the blade's neck force was reduced by 16.85%, the maximum stress decreased by 15.22%, the fatigue life increased by 76.03%, and the ultimate fracture stress improved by 20.16%. These changes align with the optimisation objectives. Subsequent control and calibration tests produced a load-strain curve that validated the simulation data with a marginal error range of 3%–10%, validating the simulation's accuracy. This research provides a robust theoretical framework for optimising the reinforcing rib and fracture resistance of rotary blades.