Mechanical properties of some granular agricultural materials used in silo design

Abstract

A b s t r a c t. The aim of this research was to provide values for different material properties considered in either traditional or more recent numerical silo design methods. Different samples of granular agricultural materials commonly stored in silos were tested. Common geotechnical devices have been used in order to make the replications easier. Based on these experiments it was determined that the different material properties were not affected by the test velocity, except in the case of Poisson ratio. From a practical point of view, the test velocity correlates well with the sliding velocity of grain during discharge. The values obtained for material properties considered in traditional silo design methods were similar to those reported by other authors. No significant differences were observed in the results obtained when using either the square shear box or the circular shear cell. The same conclusion was reached when comparing the results from direct shear tests with preconsolidated and unconsolidated samples. This means that simplified devices and procedures can be used in agricultural grains against other products. Finally, a table with the recommended values for the different parameters determined for each sample tested was provided in this work.K e y w o r d s: granular material, mechanical testing, friction, Poisson ratio, dilatancy

Mechanical properties of native maize, wheat, and potato starches

“…In the case of wet starches, cohesion varied from approximately 0.65 kPa for potato starch to approximately 0.8 kPa for wheat starch. Cohesion of agricultural materials was widely analysed by Moya et al (2002Moya et al ( , 2006. The authors determined values of apparent cohesion by the direct shear test using square and circular shear cells.…”

Mechanical properties of potato starch modified by moisture content and addition of lubricant

“…Scientific knowledge regarding powder technology is still fragmentary, design of equipment relies on empirical concepts, and process control is largely based on experts know-how (Cuq et al, 2011;Moya et al, 2013;Stasiak et al, 2010). Predictable processing, assuring quality and reduction of losses of products, are still substantial issues.…”

Mechanical properties of grain in silos for simulation designs

“…MOYA et al (2013) applied the same loads used in this study to determine the Poisson's ratio for corn, lentils and wheat grains, where they concluded that the value of this property tend to decrease with the applied load increase, an opposite fact to the one observed in this study. In numerical terms, the authors found values ranging from 0.29 to 0.34, superior numbers to the ones showed here to bean and below the value of 0.4, recommended by the POLISH STANDARD -PN-89 / B-03262 (1989 ).…”

“…The  exp . showed, for the 5kN load, its highest value of 0.12, suffering a decrease with the increase of load, until it reaches the lowest value of 0.08, a trend that was already observed by MOYA et al (2013).…”

“…RAMÍREZ et al (2010) ensure that the data about the mechanical properties as modulus of Elasticity (E), Poisson's ratio (ν) and the dilatancy angle (ψ) of the storable products are important to these simulation tools. However, according to MOYA et al (2013), this information is not commonly found in literature. Therefore, values found by various methods or even assuming values from other properties, which may result in inaccuracies in the current models.…”