Duckfoot tools connected with flexible and stiff tines: Three components of resistances and soil disturbance

The Impact of Shearing and Flexibility of Cultivator Tines on the Vertical Forces Value

“…The reported trend confirms the research by Lisowski et al, (2016) who confirmed the occurrence of the higher vertical forces at the soil shearing with rigid tines in comparison to flexible tines. It also confirms the results of the research carried out by Sánchez-Girón et al, (2005) and Jafari et al, (2011) according to which the increase of the rake angle of the tool results in the decrease of the vertical force value.…”

“…Moreover, a general trend of the decrease of the determination coefficient value along with the increase of flexibility may be observed. This trend proves a raising distribution of the registered values of forces together with the registered values of forces which may result from the raising variability of parameters of the tool operation during soil shearing (Berntsen et al, 2006;Lisowski et al, 2016). 6).…”

“…A non-monotonous nature of the course may be justified with the impact of flexibility of a shearing element on the frequency of free vibrations (Fenyvesi and Hudoba, 2010), which according to the authors positively affect the reduction of the shearing resistance value but only to the specific value of frequency. This information does not directly indicate that the tine flexibility directly affects the vertical forces; however according to Al-Kheer et al, (2011) and Lisowski et al, (2016) these forces are correlated with the shearing resistance. The decrease of the vertical force may be explained with the increase of the rake angle of the cultivator point, which accompanies the increase of the tine flexibility.…”

Vertical Forces Acting on Cultivator Tines in the Aspect of Shearing Speed and Flexibility of Tines

“…3). Indeed it confirms the results published in the papers by Lisowski et al, (2016), Al-Janobi et al, (2002) and Al-Kheer et al, (2011), but authors of the last two papers concluded that this relation is statistically insignificant. No significance of the impact of speed in case of the quoted papers may result from the research which was performed in a considerably narrow ranges of speeds, which were 0.75 -1.92 m•s -1 (Al.…”

“…Limited possibilities of using theoretical models for prediction of forces acting on the flexibly deforming model mainly result from variability of shearing elements and shearing unit geometry which take place during the tool operation in soil. This variability impedes also interpretation of the research outcomes obtained by means of experiments since it requires the inclusion of momentary values of the dynamically changing recorded signal and correlating it in time with variable parameters of shearing (Lisowski et al, 2016;Bernsten et al, 2006). Correlation of registered signals is possible only in case of measurements carried out for single shearing elements because at a given moment, particular shearing elements of the entire tool may work on various depths, which results in various horizontal shifts of cultivator points and their various rake angles.…”