Tarcie ziarnistych materiałów roślinnych

Jarosław Frączek

Abstract

This paper is the first comprehensive study of the kinetic friction in relation to granular materials of plant origin. A new description of the friction process is proposed and scientific physical models are formulated including all the 'Measurable (at present level of measurement technology) factors which influence the friction process of grain-structured plant materials. There is sonic similarity between the proposed models of external and internal, friction. In both cases, the friction force is clearly divided into adhesion and deformation components. The models can thus be considered a modification of the molecular-mechanical theory developed by Kragielski. Additionally they include a cohesion component (represented by the Las factor in the model of external friction). It must be emphasised that the use of technical terms is purely conventional since the deformation component was distinguished as a result of the mechanical approach to the friction process taking place between the microridge summits. This component expresses mathematically the processes which develop in opposition to the cohesion forces (elastic deformation, plastic deformation, cutting, rifling, etc.), In this approach, the mechanical causes of friction are a sum of molecular cohesion interactions. Instead of the usually applied Coulomb-Moh• limit state condition, the present study attempts to define the internal friction process of grain-structured plant materials based on the factors determining the course of friction. The proposed model enables physical interpretation of the obtained results. The results are applicable in many fields of agricultural technology. The determination of the friction force is crucial for almost all technologies related to grain processing, purification, sorting, transport and storage. It is a basic factor in the correct designing and industrial use of machines and equipment. In engineering, it is necessary to know all the forces applied to the construction elements to he able to calculate resistance levels and a power balance. Practical examples show that oversimplifications made at a designing stage lead to malfunctions in the operation of technical systems (i.e. clogging of feeders, excess losses, incorrect selection of drive units, silo-tank failures). The calculations of the pressure applied to silo-tank walls — usually including the forces of external and internal friction — often fail to agree with experimental results. It seems that the application of the present results will make it possible to predict more precisely the values of external and internal friction threes in relation to grain-structured plant materials.
Other language title versionsFriction of granular materials of plant origin
Book typeMonograph
Other categories ROZPRAWA_HABILITACYJNA
Author Jarosław Frączek (FoPaPE)
Jarosław Frączek,,
- Faculty of Production and Power Engineering
PublisherUniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie, MNiSW [80]
Publishing place (Publisher address)Kraków
Issue year1999
Book series /Journal (in case of Journal special issue)Zeszyty Naukowe Akademii Rolniczej im. H. Kołłątaja w Krakowie. Rozprawy, ISSN 1233-4189, (0 pkt)
No252
Pages113
Publication size in sheets9
Languagepl polski
Score (nominal)20
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