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Agricultural engineering and terramechanics
Journal o/Terramechanics, 1969, Vol. 6, No. 4. pp. 5 to 7. Pergamon Press Printed in Great Britain.
SUMMARIES Agricultural Engineering and Terramechanics by W. S6I-INE The paper is a translation of the second St. Christopher lecture delivered at the 3rd International Conference of the I.S.T.V.S. held in Essen. It deals with the broad aspects of the contribution made by agricultural engineering research to developments in the field of terramechanics. The impact of recent developments in tyre technology on tractive performance is discussed and the effect of high speed operation of tractors and cultivating implements is analysed. A n u m b e r of related topics such as all-wheel drive of tractors and implement suspension systems are also touched upon. The Effect of Sinkage Rate on Pressure Sinkage Relationships and Rolling Resistance in Real and Artificial Clays by R. G. POPE The importance of strain rate effects in soil vehicle mechanics is defined in relation to the static theories of classical soil mechanics. The effects of penetration rate on the pressure sinkage relationship in clays and artificial clay soils has been studied. Some reasons for the observed strain rate sensitivity are given and the use of artificial clay soils for model testing is suggested. A modified pressure sinkage equation including velocity effects is suggested and an example of its effect on the theoretical rolling resistance of a rigid wheel is given. " C o b r a " - - P o s i t i v e Pitch Control, Multi-Unit Articulated Test Bed by B. HANAMOTO and P. SPANSKI The paper describes the development of a multi-unit articulated vehicle (the "Cobra") as a mobile test bed. This unit was designed (a) to test the steering behaviour of vehicles having similar configuration (b) to investigate the spaced-link track concept and (c) to assess the advantages of positive pitch control. Field tests on soft soil and across fordable rivers are described. A Mark II "Polecat" was used as the reference vehicle for these tests. A Numerical Technique for Estimating the Response of a Gravity Corer by B. J. KORITES A computational technique is developed which may be used to determine the temporal and spatial dependence of displacement, velocity and acceleration of a projectile, which impacts upon a material, in terms of boundary tractions which may be arbitrary functions of velocity. acceleration or position. It is shown that such an analysis may be useful in determining the basic mechanical characteristics of a material when the projectile response is known, or in predicting the response and loads on the projectile when the boundary tractions are known. The particular case of a cylindrical gravity corer impacting upon marine sediment is studied and results are presented in terms of hypothesized soil properties.
SUMMARIES Agricultural Engineering and Terramechanics by W. S6I-INE The paper is a translation of the second St. Christopher lecture delivered at the 3rd International Conference of the I.S.T.V.S. held in Essen. It deals with the broad aspects of the contribution made by agricultural engineering research to developments in the field of terramechanics. The impact of recent developments in tyre technology on tractive performance is discussed and the effect of high speed operation of tractors and cultivating implements is analysed. A n u m b e r of related topics such as all-wheel drive of tractors and implement suspension systems are also touched upon. The Effect of Sinkage Rate on Pressure Sinkage Relationships and Rolling Resistance in Real and Artificial Clays by R. G. POPE The importance of strain rate effects in soil vehicle mechanics is defined in relation to the static theories of classical soil mechanics. The effects of penetration rate on the pressure sinkage relationship in clays and artificial clay soils has been studied. Some reasons for the observed strain rate sensitivity are given and the use of artificial clay soils for model testing is suggested. A modified pressure sinkage equation including velocity effects is suggested and an example of its effect on the theoretical rolling resistance of a rigid wheel is given. " C o b r a " - - P o s i t i v e Pitch Control, Multi-Unit Articulated Test Bed by B. HANAMOTO and P. SPANSKI The paper describes the development of a multi-unit articulated vehicle (the "Cobra") as a mobile test bed. This unit was designed (a) to test the steering behaviour of vehicles having similar configuration (b) to investigate the spaced-link track concept and (c) to assess the advantages of positive pitch control. Field tests on soft soil and across fordable rivers are described. A Mark II "Polecat" was used as the reference vehicle for these tests. A Numerical Technique for Estimating the Response of a Gravity Corer by B. J. KORITES A computational technique is developed which may be used to determine the temporal and spatial dependence of displacement, velocity and acceleration of a projectile, which impacts upon a material, in terms of boundary tractions which may be arbitrary functions of velocity. acceleration or position. It is shown that such an analysis may be useful in determining the basic mechanical characteristics of a material when the projectile response is known, or in predicting the response and loads on the projectile when the boundary tractions are known. The particular case of a cylindrical gravity corer impacting upon marine sediment is studied and results are presented in terms of hypothesized soil properties.