Research on the implementation of structural optimisation techniques in agricultural machinery design: Case study for a rotary drum mower machine

The research presented details a computer aided structural optimisation algorithm which can be implemented for the development and improvement of agricultural machinery. The algorithm has been developed based on advanced Computer Aided Design / Engineering (CAD / CAE) technologies and structural optimisation techniques. The algorithm has been put in practice by utilising different optimisation techniques (e.g. Topology, shape and size optimisation) in an industrially focussed and applied case study. In the case study, some of structural components of a power take-off (PTO) driven Rotary Drum Mower Machine (RDMM) have been considered. Each of the algorithm?s steps, which were followed for each of the optimisation procedures, have been explained in detail in order that designers/engineers in industry and researchers in academia can implement this algorithm into their own structural optimisation applications, particularly other agricultural machinery and equipment. In the case study, a total operating cycle scenario, which is representative of both conventional and over-loading conditions of the RDMM during its in-situ field operations has been established. Based on this scenario, the stress distribution and deformation behaviour of a number of structural and transmission components of the RDMM have been the focus of investigation. To enable this, stress analyses have been conducted using analytical, numerical and experimental methodologies. All analyses have been conducted for the positions of fixed tractor connection, transportation and harvest position of the RDMM. Three-dimensional Finite Elements Method (FEM) and strain-gauge based experimental strain measurement techniques have been utilised for numerical and experimental stress analyses respectively. In accordance with the physical tests and experimental analyses results, stress distributions on the components have been obtained. These results have highlighted that the highest loading condition appears during the transportation operation of the machine in the agricultural field; however, the measured stress level on the structural components was much lower than the failure limit of the component?s constituent material even at the highest level loading conditions. In addition to this, the results of the numerical analyses have been validated through analytical and experimental analyses results and by comparing the stress values. The low level stress values and validation agreement have indicated that the numerical approach correlated well with real operating conditions and that structural optimisation applications could be utilised for some of the structural components of the machine. Subsequently, three optimisation techniques (Topology, shape and size optimisation) have been illustrated on the different structural components of the RDMM by following the algorithm?s progress and systematically considering the highest loading condition. Consequently, all structural optimisation illustrations have been concluded successfully and a reduction of the components weights of 24.24 %, 18.00 % and 40.64 % have been obtained for topology, shape and size optimisation case studies respectively. According to the optimisation outputs, technical drawings of the optimised components are presented. KEYWORDS: Computer Aided Design (CAD), Computer Aided Engineering (CAE), Finite Elements Method (FEM), Structural Optimisation, Agricultural Machinery Design, Mower Machine.