Effects of moisture content, loading rate, and grain orientation on fracture resistance of barley grain

Abstract

Force and deformation curves of agricultural materials must be provided for the proper design of harvesting and processing machineries. In this research, the fracture resistance of barley grain was measured in terms of the grain rupture force and energy. In this study, 8 treatments were performed as a randomised complete block design with 10 replications. The barley grains were quasi-statically loaded in horizontal and vertical orientations with the moisture content at four levels: 7.34, 12.11, 16.82, and 21.58% dry basis, and loading rates at two levels: 5 and 10 mm/min. Based on the results obtained, the force required for initiating the grain rupture decreased from 161.97 to 93.94 N, and from 75.37 to 50.16 N, and the energy absorbed at the grain rupture increased from 36.42 to 74.70 mJ and from 27.34 to 62.65 mJ, for horizontal and vertical orientations, respectively, with the increase in the moisture content from 7.34 to 21.58% dry basis. This showed that seeds are more flexible in the horizontal orientation.

The Effects of Moisture Content and Loading Orientation on Some Physical and Mechanical Properties of “Tafo Hybrid” and “Amelonado” Cocoa Beans

“…On their part, Tavakoli et al . () explained such observation in terms of the stress induced, indicating that higher stress is developed during the longitudinal loading because of the smaller contact surface.…”

“…() for hazelnut, Tavakoli et al . () for barley grain, Altuntas and Yildiz () for faba and Bagheri et al () for rice. It may be concluded from these results that wet seed or grain absorbs energy more efficiently from applied force which weakens the intermolecular bonds (Smith, ) and causes it to fail at a lower load than dry produce.…”

“…). Similar trends in the mechanical properties have been reported for filbert nut and kernel (Pliestic et al ., ), African nutmeg (Burubai et al ., ), faba bean (Altuntas and Yildiz, ) and barley grains (Tavakoli et al ., ) that were quasi‐statically loaded in the horizontal and vertical orientations. The compressive stress at rupture point (i.e., fracture stress) is indicative of the ultimate compressive strength beyond which the material will fracture.…”

“…The rupture force may therefore be lower in the longitudinal orientation even though less energy is absorbed. On their part, Tavakoli et al (2009) explained such observation in terms of the stress induced, indicating that higher stress is developed during the longitudinal loading because of the smaller contact surface. There was about 1.8-fold greater rupture force when "Amelonado" beans were compressed in the lateral orientation (mean value 73.42 N) compared with compression in the longitudinal orientation (mean value 41.1 N).…”

Mechanical behaviour of several layers of selected plant seeds under compression loading

“…The pressure gradient thus causes a change in the mechanical behaviour of plant seeds during pressing. To some extent, however, the pressing force or volume energy and the deformation characteristics are globally (strictly) monotonic increasing functions (Faborode, Favier 1996;Očenášek, Voldřich 2009;Tavakoli et al 2009;Herák et al 2010;Herák et al 2011); thus, if the pressing force is increased the deformation increases. In the same way, with some value of the pressing force, volume energy and the deformation characteristics are the local monotonic functions, and thus if the deformation is increased, the pressing force remains constant or decreases.…”