| Summary: | Energy from biomass accounts for 70% of all renewables used for heat and electricity production. Such a significant share of biomass determines the need for the investigation of their mechanical properties, as most of the lignocellulosic material requires cutting, chipping or milling before its utilization for energy purposes. Therefore, the knowledge about cutting resistance, bending stiffness, and impact strength of the energy plants is very important. The values of these parameters are used in the proper selection of shredding machines and their elements, wrapping nets or determination of power demand during raw material conversion. This paper presents the results of research on the mechanical properties of selected energy plants. The scope of the research included three different plant species: <i>Miscanthus × giganteus</i>, <i>Rosa multiflora</i>, and <i>Salix viminalis</i>, investigated in terms of cutting resistance, bending stiffness and impact strength of stalks. The results showed that the average stalk cutting resistance for the rotation speed of 4200 RPM was 0.17 N·mm<sup>−2</sup> for the <i>Miscanthus × giganteus</i>, 0.15 N·mm<sup>−2</sup> for the <i>Rosa multiflora</i> and 0.2 N·mm<sup>−2</sup> for the <i>Salix viminalis</i>. Meanwhile, for a rotation speed of 3200 RPM, the cutting resistance amounted to 0.15 N·mm<sup>−2</sup> for <i>Miscanthus × giganteus</i>, 0.16 N·mm<sup>−2</sup> for <i>Rosa multiflora</i> and 0.18 N·mm<sup>−2</sup> for <i>Salix viminalis</i>. For the impact measurements, the <i>Salix viminalis</i> exceeded 40 J·mm<sup>−2</sup> of absorbed energy. Meanwhile, the average impact strength value for the <i>Rosa multiflora</i> was 0.53 J·mm<sup>−2</sup> and for the <i>Miscanthus × giganteus</i> was 0.22 J·mm<sup>−2</sup>. The bending stiffness of <i>Miscanthus × giganteus</i> at an average modulus of 3.44 GPa was 1.1 N·m<sup>2</sup> for the basal zone, 0.78 N·m<sup>2</sup> for the central zone, and 0.72 N·m<sup>2</sup> of the apical zone. For the average Young’s modulus of 0.19 GPa, the bending stiffness of the <i>Rosa multiflora</i> reached a value of 0.64 N·m<sup>2</sup> for the basal zone, 0.23 N·m<sup>2</sup> for the central zone, and 0.28 N·m<sup>2</sup> for the apical zone. The <i>Salix viminalis</i>, with an average modulus of elasticity of 0.23 GPa, achieved bending stiffness in the basal zone of 0.99 N·m<sup>2</sup>, the central zone 0.33 N·m<sup>2</sup>, and the tip zone 0.38 N·m<sup>2</sup>. This research makes it possible to expand our knowledge in the field of biomass processing and construction of agricultural machinery with higher processing efficiency.
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