Estimating the variability of tillage forces on a chisel plough shank by modeling the variability of tillage system parameters

Abstract

In this paper, a probabilistic approach is proposed for quantifying the variability of the tillage forces for the shank of a chisel plough with narrow tines and to estimate the failure probability. An existing threedimensional analytical model of tool forces from McKyes was used to model the interaction between the tillage tools and the soil. The variability of tillage forces was modeled, taking into account the variability of soil engineering properties, tool design parameters and operational conditions. The variability of the soil engineering properties was modeled by means of experimental observations. The dispersion effect of each tillage system parameter on the tillage forces was determined by a sensitivity analysis. The results show that the variability of the horizontal and vertical forces follows a lognormal distribution ((ߤ ൌ ͲǤ ͺ ʹǡߦ ൌ ͲǤ ͶͶͻ); (ߤ ൌ ͲǤ ͲͲͶǡߦ ൌ ͲǤ ͶͶ)) and the relationship between these forces is positive and quasi-linear ሺߩ(ܲ ு ǡܲ) = 0.93). This lognormal variability was integrated into the estimation of the failure probability for the shank by using Monte Carlo simulation (MCS) and the first-order reliability method (FORM). The results obtained by these two methods, with the assumption of non-correlation between the horizontal and vertical forces, were almost identical. However, the FORM method was faster and simpler, compared to the MCS technique. Furthermore, the correlation between the horizontal and vertical forces has no significant effect on the failure probability, regardless of the correlation strength. Therefore, it is concluded that the FORM method can be used to estimate the failure probability without considering the correlation between horizontal and vertical forces.

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.…”

“…According to some authors (Fenyvesi and Hudoba, 2010), flexibility of the shearing element influences the own vibrations frequency, which, as a result, causes decrease of the shearing resistance value, but only to the specific value of frequency. This information shows explicitly that the tine flexibility directly influences the vertical forces, but according to Al-Kheer et al, (2011) and Lisowski et al, (2016) those forces are correlated with the shearing resistance. The reduction of the vertical force value reported in the further part may be explained with the growing intensity of the increase of the rake angle of the cultivator point which accompanies the increase of the tine flexibility.…”

“…According to many authors, simplification of cultivation treatments causes reduction of energy consumption, reduces soil degradation and favourably influences the yields (Chen et al, 2005;Talarczyk and Zbytek, 2006;Rouw et al, 2010). The consequence of the discussed trend is intensification of the experimental research carried out for single shearing elements (Sahu and Raheman, 2006;Zhang and Chen, 2017;Manuwa, 2009) and whole tools (Przybył et al, 2009;Al-Janobi et al, 2002) and theoretical research (Ucgul et al, 2015;Al-Kheer et al, 2011;Wahed and Aboukarima, 2007), devoted to the influence of the cultivator tine on soil.…”

Reliability-based design optimization of shank chisel plough using optimum safety factor strategy

“…In our work McKyes and Ali's model (1977), as shown in Fig. 1, was used to estimate the forces acting on a tillage tool with three main modifications (Abo Al-kheer et al, 2011). The effects of soil-tool adhesion and tool speed were taken into account.…”

Design Optimization of the Plough Working Surface by Computerized Mathematical Model

“…The optimization process requires the consistency with the experimental data and a simple analytical and integral structure, which involves very short processing time, in order to be profitably used in the context of optimization cycles which, for their part, involve the computation of multiple solutions. Therefore, the possibility of using costly numerical techniques of integration (CFD, DEM, SHP) (Abo Al-Kheer et al, 2011;Formato and Faugno, 2007;Kasisira, 2005;Oida and Momozu, 2002;Ros et al, 2008;Rucins and Vilde, 2004;Rucins and Vilde, 2005;Saarilahti, 2002) will be sacrificed on the altar of an analytical -integral approach, which prefers the rapidity of the calculation to the alleged accuracy of the results obtained by differential-algebraic techniques. Among the integral relations, that is possible to find in the vast scientific production that characterizes the subject in question, we have used those developed by Godwin et al, 2007. According to this approach, the complete expression of the total resistance offered by the engaged tool during the working soil (draught force) Lt [kN] may be considered as the resultant of the component necessary for the rupture of the soil (cut), the component necessary for its lifting and then overturning (inertia) and that generated by the phenomenon of friction and adhesion inside the soil considered and due to the interaction of the latter with the working surface (friction).The draught force is, therefore, expressed as the sum of all the components defined above:…”