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

Abstract

Herák D., Kabutey A., Sedláček A., GŰrdil G., 2012. Mechanical behaviour of several layers of selected plant seeds under compression loading. Res. Agr. Eng., This article is focused on the determination of the mechanical behaviour of several layers of plant seeds namely; garden pea (Pisum sativum L.), common bean (Phaseolus vulgaris L.), common sunflower (Helianthus annuus L.) and jatropha (Jatropha curcas L.) seeds under compression loading. The results from the experiment showed that during compression plant seeds may change their mechanical behaviour that is deformation characteristic ceases to be a function of growing and beginning to resemble that of trigonometric functions and this behaviour is called the "wave effect". Also the strain value at which there is no further change of the mechanical behaviour is actually a local maximum of deformation characteristic and this is called the limit deformation. Exceeding this value can cause vibration of the presser including other negative factors which influences the process of pressing. The amounts of the limit deformation, strain energy and volume energy for jatropha, common bean, common sunflower and garden pea were determined in this experiment. From the calculated amounts of the volume energy, garden pea had the best resistance to change in the mechanical behaviour due to the fact that its change in the mechanical behaviour was not discovered. The other plant seeds; common beans, common sunflower and jatropha with respect to resistance to change in the mechanical behaviour followed in that order of magnitude.Keywords: jatropha; common bean; garden pea; common sunflower; pressing; wave effect In oil extrusion with usual extruders used in industrial practice, there is non-linear compression of pressed mixture incurred during the processing. This means that the compression is combination of translational movement moving and rotational movement. For better understanding of mechanical behaviour of plant seeds under compression loading, it is necessary first to understand mechanical behaviour of one free placed seed and one layer of seeds with limited deformation and also mechanical behaviour of more layers of the seeds. Earlier experiments conducted with plant seeds, namely jatropha, palm oil, sunflower and knotweed, showed that the specific strain energy required for deformation of one free placed seed was much greater than for pressing the same seeds layer (Fomin 1978; Blahovec, Řezníček 1980;Herák et al. 2007). There is a dynamic effect on plant tissue and thus higher cell damage (Addy et al. 1975), which is arising due to radial pressure during pressing, the gradual deformation of seeds, seeds of mutual friction and friction of the seed on the pressing vessel. There is also a required gradient of pressing pressure, and thus if the pressure gradient is inVol. 58, 2012, No. 1: 24-29 Res. Agr. Eng.

Damage resistance and compressive properties of bulk maize kernels at varying pressing factors: Experiments and modeling

“…The volume energy of bulk kernels was calculated using following equation (Chakespari, Rajabipour, & Mobli, ; Gupta & Das, ; Łysiak, ): where E v is the volume energy (J/mm 3 ); V is the volume of the bulk samples (mm 3 ), as determined using the below equation (Chakespari et al, ; Herak, Kabutey, Sedláček, & Gurdil, ): where D is the vessel diameter (mm); H x is the initial height of bulk kernels (mm).…”

“…The hardness of the bulk kernels is the ratio of compressive force to that of the kernel maximum deformation and was calculated using the following equation (Herak et al, ): where S x is the hardness of the bulk kernels (kN/mm); F m is the compressive force (N); and D x is the maximum deformation of the bulk kernels (mm), which is a measure of the maximum deformation under the action of compression force.…”

Compressive stress, repetitive strain, and optimum expression of oil from bulk volumes of sesame seeds

“…Strain, ε (–) induced in the compressed oilseed material was determined as the ratio of the peak deformation, (mm) during a test to the initial product depth, (mm) established prior to the commencement of the test. Energy required to achieve a given deformation (Herák, Kabutey, Sedláček, et al, ) of the compressed product mass, at the indicated loads is deformation energy, E (J) and was determined as where is the number of subdivisions of the deformation axis, which in this case was logged by the test equipment in incremental steps of 0.01 mm; (N) is the compressive force for a known deformation, (mm). Specific mechanical energy is energy per unit mass of the material processed (Evon, Amalia Kartika, Cerny, & Rigal, ).…”

Mechanical Behaviour of Bulk Seeds of Some Leguminous Crops under Compression Loading

“…4). This is the area beneath the force-deformation curve and is numerically computable as follows: (4) where: i = number of subdivisions of the deformation axis in this case done in step measurements of 0.01 mm, as logged by the test equipment and as set forth by Herak et al (2012) F n (N) = compressive force for a known deformation δ n (mm), E (J) = deformation energy Volume deformation energy, (N mm -3 ) is a function of the induced volumetric strain and is determinable by Eq. 5 (5) The Modulus of deformation, M n (MPa) was determined using Eq.…”