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December 2017 (published: 25.12.2017)
Home > Issue > Mathematical simulation of normal contact pressure forces on side knife edges during food cutting
Mathematical simulation of normal contact pressure forces on side knife edges during food cutting
Aqeev O.V., Naumov V. A., Fatykhov Yu. A.
In order to ensure resource conservation while cutting food materials, the system of forces of useful and harmful resistances acting on a knife during fish cutting has beenconsidered. The fish rheological properties are described by a three-element model for linear viscoelastic material. Based on the differential equation for the state of material, mathematical model for normal contact pressure on the knife side edge has been developed. Mathematical models for the normal contact pressure force, as well as for a dimensionless force, have been proposed. It is found out that the force of the normal contact pressure on the knife side edge increases strictly monotonically as the knife is immersed into the material, as well as when the sharpening angle and the blade thickness increases. This force depends greatly on the velocity for the small values of the blade speed, for the large values it practically reaches its limit. It is found out that the force of the contact pressure on the knife side edge depends on the geometry of the knife inclined edge. The force in question increases greatly with the increasing in material rigidity. It is shown that the nature of reaching the limit of this force does not depend on the knife design parameters, but is related to the cutting speed and fish viscoelastic properties. This is due to extreme increasing in the dynamic material rigidity with the strain rate increasing. It is found out that the magnitude of the force is simultaneously influenced by such physical factors as the magnitude of the material deformation, the contact area, and the stress relaxation in the material. Based on the simulation results to reduce energy consumption it is recommended to cut the fish before the stage of death stiffening. In addition, it is recommended to perform fish cutting at the stage of autolysis after resolution of death stiffening before raw material spoilage. It is also advisable to cut with increasing raw material temperature and to reduce the knife thickness. The proposed recommendations have been aligned with the results of experimental researches.
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Keywords: pretreatment of animal raw materials; food cutting; rheology; force of contact pressure; math modeling; side face of the knife; fish
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