Description

The importance of economical production of agricultural materials, especially crops and animal products serving as base materials for foodstuffs, and of their technological processing (mechanical operations, storage, handling etc.) is ever-increasing. During technological processes agricultural materials may be exposed to various mechanical, thermal, electrical, optical and acoustical (e.g. ultrasonic) effects. To ensure optimal design of such processes, the interactions between biological materials and the physical effects acting on them, as well as the general laws governing the same, must be known. The mechanics of agricultural materials, as a scientific discipline, is still being developed, and therefore has no exact methods as yet, in many cases. However, the methods developed so far can already be utilized successfully for designing and optimizing machines and technological processes. This present work is the first attempt to summarize the calculation methods developed in the main fields of agricultural mechanics, and to indicate the material laws involved on the basis of a unified approach, with all relevant physico-mechanical properties taken into account. The book deals with material properties, gives the necessary theoretical background for description of the mechanical behaviour of these materials including modern powerful calculation methods and finally discusses a large number of experimental results. Many of them can only be found in this book. Special attention is paid to the unified approach concerning theory and practice. The systematic treatment of the material makes the book useful to a wide circle of designers, researchers and students in the field of agricultural engineering. The book can also be used as a textbook at technical and agricultural universities.

Table of Contents

1. The development and importance of agricultural mechanics. 2. Physical properties of agricultural materials. Shape and size. Surface area. Volume and density. Thermal and hygroscopic expansion. 3. Mechanical properties. 4. Thermal properties. Specific heat. Heat-conduction coefficient. Temperature conductivity. 5. Electrical properties. Dielectric constant and dielectric loss. 6. Optical properties. Reflectance properties. Transmittance properties. 7. Water storage in agricultural materials. Physics of water storage. Adsorption and desorption of water. Equilibrium moisture content. Moisture adsorption by hygroscopic materials. Internal moisture movement. Mass-transfer at the surface. Mass-transfer coefficients. Moisture gradients. Contact moisture exchange. The theory of drying. General relationships in the drying process. Heating and cooling of deep piles. Heat production in biological materials during storage. Moisture exchange of fruits and vegetables with the air. 8. The background of rheology. Characteristics of biological materials. Ideal materials and their properties. Time-dependent behavior of materials; viscoelasticity. Creep. Recovery. Relaxation. Linearity. Rheological models. Rheological equations. Integral representation of viscoelastic constitutive equations. Behavior of viscoelastic materials under oscillating loads. Nonlinear constitutive equations. Temperature effects. Non-Newtonian fluids; viscosimetry. 9. Contact stresses. Contact stress in elastic bodies. Contact stress in viscoelastic bodies. The theory of the rigid dye; the Boussinesq problem. 10. Impact loading. Impact of elastic bodies. Impact of viscoelastic bodies. Application of cushioning materials. 11. The finite-element method. Concept of the method. Shapes of elements and the displacement function. Embedding the elements into the continuum. Finite element formulation. Viscoelastic stress analysis; numerical method. Application of the finite-element method to flow fields. 12. App

Details

Language:
English
Copyright:
© 1986
Published:
Imprint:
Elsevier Science
eBook ISBN:
9780444601032
Print ISBN:
9780444995230

About the author

G. Sitkei

Affiliations and Expertise

University of Forestry and Food Science, Sopran, Hungary

Reviews

@qu:The author has achieved his aim of summarizing basic principles and relationships, and describing available calculation methods. ... a valuable reference for libraries, practicing engineers, and researchers who require information on properties of agricultural materials. It would also be useful as a test for a graduate level course on the subject. @source: Applied Mechanics Review