The effects of time of sugar beet root storage on the parameters determined by impact testing were studied. The 9 mm diameter and 20 mm high cylindrical samples were cut crosswise and lengthwise along the root axis. The impact velocity was 1 m s-1 and the change in the response force over time was observed at both ends of the sample. The measurements were made directly after harvesting and after 24, 48, 96 and 120 h of storage at room temperature. Failure stress and strain, impact energy, absorbed energy, Young's modulus and shock wave speed were determined in the sample tissue from the change in the response force at both ends of the sample. A drop of 40% in the average values of the energy required to damage the samples was observed during 120 h of storage. A similar dependence was found for the energy absorbed by the sample as evidenced by the greater susceptibility of the roots to impact loads. The experiment confirms the importance of critical stress criterion for cylindrical samples of sugar beet. The velocities of shock wave propagation obtained from the samples during impact were in the range of 220-384 m s-1 and were not correlated with the other experimental parameters. K e y w o r d s: sugar beet root, impact energy, absorbed energy, storage time
The investigations on the response of bone tissue under different loading conditions are important from clinical and engineering points of view. In this paper, the influence of nesfatin-1 administration on rat humerus mechanical properties was analyzed. The classical three-point bending and impact tests were carried out for three rat bone groups: control (SHO), the humerus of animals under the conditions of established osteopenia (OVX), and bones of rats receiving nesfatin-1 after ovariectomy (NES). The experiments proved that the bone strength parameters measured under various mechanical loading conditions increased after the nesfatin-1 administration. The OVX bones were most susceptible to deformation and had the smallest fracture toughness. The SEM images of humerus fracture surface in this group showed that ovariectomized rats had a much looser bone structure compared to the SHO and NES females. Loosening of the bone structure was also confirmed by the densitometric and qualitative EDS analysis, showing a decrease in the OVX bones’ mineral content. The samples of the NES group were characterized by the largest values of maximum force obtained under both quasi-static and impact conditions. The energies absorbed during the impact and the critical energy for fracture (from the three-point bending test) were similar for the SHO and NES groups. Statistically significant differences were observed between the mean Fi max values of all analyzed sample groups. The obtained results suggest that the impact test was more sensitive than the classical quasi-static three-point bending one. Hence, Fi max could be used as a parameter to predict bone fracture toughness.
Principles, characterization and stress analysis of the clutch components with infinitely variable adjustment of the torsional flexibility at the load occurring during the operation of the machine drive system, are presented. The finite element method was used for the stress analysis of the clutch. Results of the analysis confirm the correctness of the clutch construction in terms of their strength.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.