Experimental study of the physical and mechanical properties of an elastomer for the manufacture of shock-absorbing working bodies of agricultural machines

One of the significant factors affecting seed damage is the ability of the working surface of agricultural machines to absorb shock. The use of steel structural elements leads to significant seed damage. Therefore, in order to achieve high seed integrity, it is necessary to replace steel rigid structural elements that interact with seeds with polyurethane elastomers that can withstand significant tensile-compressive elastic deformations and absorb shock impact on seeds. A mobile modular sorting and treatment complex is planned to be created. The working bodies and elements of the technical devices included in this complex will be made of highly elastic polyurethane, which will make it possible not only to be sure of the reliability of the working bodies, but also the seed safety. To manufacture shock-absorbing working bodies of technical devices recommended for use in the technology of preparing seeds for sowing, a polyurethane elastomer of the Adipren-L167 brand was chosen. A sample cut with a stamping knife made from a polyurethane plate was subjected to tensile deformation until rupture on an original tensile testing machine designed and manufactured in the Azov-Black Sea Engineering Institute. There have been determined the characteristics of strength and plasticity of the Adipren-L167 elastomer. There has been built a graph of the dependence of stress on the standard deviation of the sample. A comparative analysis of the physical and mechanical characteristics of the elastomer obtained during the experiments with similar characteristics indicated by the manufacturer showed that the ultimate strength of the experimental sample is slightly lower than the value indicated by the manufacturer. There has been determined the true stress at the moment of rupture. This characteristic was not declared by the manufacturer, but it is very significant when choosing highly elastic polyurethane as a material for the manufacture of working bodies of agricultural machines operating under conditions of significant tensile deformations and dynamic loading. An analysis of the results of experimental studies of highly elastic polyurethane made it possible to formulate requirements for the choice of an elastomer for the manufacture of shock-absorbing working bodies of agricultural machines.