MODELLING OF A MULTI-CROP THRESHER: FINITE ELEMENT ANALYSIS OF THE THRESHING DRUM.
CAD software are tools which have been developed to aid engineers in design and design optimization process. Series of multi-crop threshers have been modelled and developed using different CAD software but many of those research works do not perform Finite Element Analysis of the components of the thresher in order to determine the deformations in those components as a result of the operating condition of the machine. A multi-crop thresher was modelled using Autodesk Inventor (a CAD software) and Finite Element Analysis (FEA) was performed on the threshing drum of the machine in this write-up. The various component parts of the machine were modelled in the parts environment of the software, assembled in the assembly environment and exploded in the presentation environment after which drawings of the machine (isometric, autographic and parts) were extracted from the drawing environment of the software. For the FEA of the threshing drum, the operating conditions of the drum were determined such as bearing load, threshing torque and the force exerted by the feed material on the bars attached to the threshing drum which were applied on the drum. The drum was discretized into finite elements and FEA was carried out in the analysis environment of the software. It was discovered that under the operating conditions to which the threshing drum was subjected to for the FEA, there was no failure of the drum though little deformation was recorded. The maximum Von mises stress of 2.246 MPa which is the working stress of the threshing drum was less than the yield strength of stainless steel (the material make-up of the drum) of 250 Mpa. The maximum first and third principal stress of 2.10896 MPa and 0.2639 MPa respectively are less than the yield strength of the material while the maximum first and third principal strain of 0.0000099 and 0.000000102 shows infinitesimal deformation. The overall maximum displacement of 0,0360034 mm and the maximum displacement in the x, y and z axis of 0.036 mm, 0.0155 mm and 0.001587 mm shows little deformation in the threshing drum under the operating conditions it was subjected to. The factor of safety obtained was also very high indicating a safe design. After modelling the multi-crop thresher and analyzing the FEA result of the threshing drum, it can be concluded that the design is a safe one since it passed all the tested criteria.
Keywords: Multi-crop thresher, Autodesk Inventor, Finite Element Analysis, Computer Aided Design, Modelling.
