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: Miscanthus × giganteus, Rosa multiflora, and Salix viminalis, 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⁻² for the Miscanthus × giganteus, 0.15 N·mm⁻² for the Rosa multiflora and 0.2 N·mm⁻² for the Salix viminalis. Meanwhile, for a rotation speed of 3200 RPM, the cutting resistance amounted to 0.15 N·mm⁻² for Miscanthus × giganteus, 0.16 N·mm⁻² for Rosa multiflora and 0.18 N·mm⁻² for Salix viminalis. For the impact measurements, the Salix viminalis exceeded 40 J·mm⁻² of absorbed energy. Meanwhile, the average impact strength value for the Rosa multiflora was 0.53 J·mm⁻² and for the Miscanthus × giganteus was 0.22 J·mm⁻². The bending stiffness of Miscanthus × giganteus at an average modulus of 3.44 GPa was 1.1 N·m² for the basal zone, 0.78 N·m² for the central zone, and 0.72 N·m² of the apical zone. For the average Young’s modulus of 0.19 GPa, the bending stiffness of the Rosa multiflora reached a value of 0.64 N·m² for the basal zone, 0.23 N·m² for the central zone, and 0.28 N·m² for the apical zone. The Salix viminalis, with an average modulus of elasticity of 0.23 GPa, achieved bending stiffness in the basal zone of 0.99 N·m², the central zone 0.33 N·m², and the tip zone 0.38 N·m². This research makes it possible to expand our knowledge in the field of biomass processing and construction of agricultural machinery with higher processing efficiency.

From the producers’ point of view, there is no universal and quick method to predict bruise area when dropping an apple from a certain height onto a certain type of substrate. In this study the authors presented a very simple method to estimate bruise volume based on drop height and substrate material. Three varieties of apples were selected for the study: Idared, Golden Delicious, and Jonagold. Their weight, turgor, moisture, and sugar content were measured to determine morphological differences. In the next step, fruit bruise volumes were determined after a free fall test from a height of 10 to 150 mm in 10 mm increments. Based on the results of the research, linear regression models were performed to predict bruise volume on the basis of the drop height and type of substrate on which the fruit was dropped. Wood and concrete represented the stiffest substrates and it was expected that wood would respond more subtly during the free fall test. Meanwhile, wood appeared to react almost identically to concrete. Corrugated cardboard minimized bruising at the lowest discharge heights, but as the drop height increased, the cardboard degraded and the apple bruising level reached the results as for wood and concrete. Contrary to cardboard, the foam protected apples from bruising up to a drop height of 50 mm and absorbed kinetic energy up to the highest drop heights. Idared proved to be the most resistant to damage, while Golden Delicious was medium and Jonagold was least resistant to damage. Numerical models are a practical tool to quickly estimate bruise volume with an accuracy of about 75% for collective models (including all cultivars dropped on each of the given substrate) and 93% for separate models (including single cultivar dropped on each of the given substrate).

Farmers belong to the group of high risk in terms of developing work-related musculoskeletal disorders. A series of tasks, which are often performed in an uncomfortable position, loads exceeding farmers’ physical abilities, as well as high repetition of work movements, all contribute significantly to the development of irreversible changes in the musculoskeletal system. Taking into account the above-mentioned circumstances, this study aimed at workload assessment expressed in maximal voluntary contraction (%MVC) while delivering dairy-cattle feed. In the initial phase of this study, a questionnaire was carried out, based on which a load of individual segments of the musculoskeletal system during work was subjectively assessed. On this basis, the areas of the musculoskeletal system were selected in which a risk of the ailments’ occurrence was the highest. These studies were carried out directly on farms, where the surface electromyography (sEMG) method was used. On the basis of obtained results, the permissible human load was determined based on mass of the shovel which was used to load and unload maize silage. The obtained results can be used to ensure safe conditions while performing work with high muscle exertion.