Study of the resistance of bast fiber crop stems to abrasive wear

The development of technical means with optimal design parameters for harvesting bast fiber crops is closely related to the mechanical and technological properties of plant material. These properties characterize the structure of the stem, resistance to loads acting on it, behavior under various deformations and destruction, friction on working surfaces, etc. The stems of bast fiber crops, such as industrial hemp, contain fibers that have abrasive properties and cause rapid wear of the cutting edges of knives. However, there are still no studies of the resistance of the stems to abrasive wear. In order to determine the resistance of the fibrous layer of hemp stems to abrasive wear, the authors studied the physico-mechanical and strength properties of the stems of industrial hemp of three varieties – Lyudmila, Nadezhda, and Surskaya. The authors studied the micro-relief of the surface of the bast fiber layer of industrial hemp using atomic force microscopy with a scanning probe microscope. The abrasion experiment was carried out on the AT-100 rotary abrasion tester in accordance with GOST R17076-1- 2014. The study of the microrelief showed a more developed outer surface with a brightly colored fibrous structure. The greatest differences in microroughnesses were observed between the lower and apical parts of the stem. Indicators characterizing the mechanical properties of bast fibers, such as elasticity, hardness and modulus of elasticity, differed in various parts of the stem. The greatest value of the modulus of elasticity and hardness of the fibers was found in the middle part of the stem. Experimental data on the volumetric wear of the bast fiber layer of industrial hemp stems showed that the stems of the Nadezhda variety have the highest abrasion resistance (an abrasion index of 1.67), the Lyudmila variety has the lowest (an abrasion index of 3.71). The research results should be taken into account when designing and developing innovative harvesting machines and choosing abrasive wear-resistant materials to manufacture the cutting edges of knives.

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