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Active vibration isolation and active vehicle suspension
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ABSTRACTS
~6. N. Nagata. A cylinder method for estimating the shear strength of soils in the paddy field. Bull. fac. Agric. Mie Univ. 36, 1 l 1 (1967). The cylinder (inner diameter 4.8 cm; height 5.5 cm) is pushed 3 cm deep into the soil surface and the soil core is sheared at a level of 1.5 cm above the cylinder bottom. In laboratory experiments the cylinder method and the direct-shear test gave relatively high correlation coefficients with silty loam and sandy clay soils. In field tests on clay or clayey loam, the cylinder method was better from a practical standpoint and more exact than the vane shear test. Shear strength increased with depth and reached a maximum in the plowsole. It was higher in drained paddy soil than in undrained soils. (Soil atzd Fertilizers, 1968.) 97. Igor L. Paul and Erich K. Bender. Active vibration isolation and active vehicle suspension. Massachusetts Inst. Technol., Cambridge. 73 pp. (Nov. 1966). The feasibility of using "active" elements in suspension systems for high speed ground vehicles to improve vibration isolation characteristics is considered. The characteristics of vehicle excitations (to the suspensions and to the vehicle body) are discussed and a mathematical expression for the suspension input is obtained. Based on data of h u m a n tolerance to vertical vibrations a comfort criterion (to vibrations) is established. The problem of vibration isolation to best satisfy this criterion is considered in terms of optimizing the parameters of a given suspension configuration and in terms of finding an optimum transfer function for an unspecified suspension configuration. The methodology for obtaining these optimum solutions for a given comfort criterion is developed and solutions are obtained for the case of vertical vibrations of a two-degree-of-freedom system in which the root mean square acceleration of the vehicle is to be minimized for a given permissible suspension excursion. The optimum suspension transfer function for this case indicates that feedback of both vehicle and unsprung mass acceleration is required. (U.S. Gov. Res. Dev. Rep.. 1967, PB 173648.) 98. E. M. Rutledge, L. P. Wilding and M. Elfield. Automated particle size separation by sedimentation. Proc. Soil. Sci. Soc. Am. 31,287 288 (1967). The design and operation of a fractionator developed to perform the common sedimentation-decantation procedure automatically is described. Included are line drawings and a photograph of this equipment. (Author's summary.) 99. G. R. Saini and A. I. Stewart. Comparison of rapid methods of soil moisture determination based on Archimedes' principle. Can. J. Soil Sci. 47, 145 147 (1967). Experiments with four different soils showed that Chang's method was simplest and quickest for routine determinations without requiring expensive equipment. (Soil and Fertilizers, 1967.) 100. J. H. Schmertmann. Static penetrometers for soil exploration. Civil Engng ASCE, 71-73 (June 1967). Research at the University of Florida indicates that the static cone penetration test offers a useful method for soil exploration. One type of static cone penetration equipment evaluated, of Dutch make, provides data on soil bearing capacity and friction. This information can then be used to identify the type of soil penetrated, without taking borings. A Swedish-made cone penetrometer was also evaluated. Although it does not have the capacity of the Dutch instrument, it does oiler a good method for shallow explorations. Cost of soil investigations with these instruments is competitive with standard penetration test investigations. (Author's summary.) 101. E. T. Selig. Soil compaction study, Volume I. Introduction and results of initial phases. Res. Inst., Chicago. 196 pp. (March 1967). A study has been undertaken to determine: the desired characteristics of compacted soils, the best method for measurement and specification of proper compaction, and the effectiveness of various ways of achieving compaction. This report is Volume I of a series of f n a l reports presenting the results of the study. The research was divided into four basic phases: field pilot studies, laboratory studies, field test program, and data reduction and analysis. This volume covers the field pilot and the laboratory studies. The latter includes: evaluation and calibration of portable nuclear soil moisture-density gages, development of automated penetrometer-plate-CBR apparatus, evaluation of cone penetrometer characteristics, classification of the subgrade soils and base course materials,
ABSTRACTS
~6. N. Nagata. A cylinder method for estimating the shear strength of soils in the paddy field. Bull. fac. Agric. Mie Univ. 36, 1 l 1 (1967). The cylinder (inner diameter 4.8 cm; height 5.5 cm) is pushed 3 cm deep into the soil surface and the soil core is sheared at a level of 1.5 cm above the cylinder bottom. In laboratory experiments the cylinder method and the direct-shear test gave relatively high correlation coefficients with silty loam and sandy clay soils. In field tests on clay or clayey loam, the cylinder method was better from a practical standpoint and more exact than the vane shear test. Shear strength increased with depth and reached a maximum in the plowsole. It was higher in drained paddy soil than in undrained soils. (Soil atzd Fertilizers, 1968.) 97. Igor L. Paul and Erich K. Bender. Active vibration isolation and active vehicle suspension. Massachusetts Inst. Technol., Cambridge. 73 pp. (Nov. 1966). The feasibility of using "active" elements in suspension systems for high speed ground vehicles to improve vibration isolation characteristics is considered. The characteristics of vehicle excitations (to the suspensions and to the vehicle body) are discussed and a mathematical expression for the suspension input is obtained. Based on data of h u m a n tolerance to vertical vibrations a comfort criterion (to vibrations) is established. The problem of vibration isolation to best satisfy this criterion is considered in terms of optimizing the parameters of a given suspension configuration and in terms of finding an optimum transfer function for an unspecified suspension configuration. The methodology for obtaining these optimum solutions for a given comfort criterion is developed and solutions are obtained for the case of vertical vibrations of a two-degree-of-freedom system in which the root mean square acceleration of the vehicle is to be minimized for a given permissible suspension excursion. The optimum suspension transfer function for this case indicates that feedback of both vehicle and unsprung mass acceleration is required. (U.S. Gov. Res. Dev. Rep.. 1967, PB 173648.) 98. E. M. Rutledge, L. P. Wilding and M. Elfield. Automated particle size separation by sedimentation. Proc. Soil. Sci. Soc. Am. 31,287 288 (1967). The design and operation of a fractionator developed to perform the common sedimentation-decantation procedure automatically is described. Included are line drawings and a photograph of this equipment. (Author's summary.) 99. G. R. Saini and A. I. Stewart. Comparison of rapid methods of soil moisture determination based on Archimedes' principle. Can. J. Soil Sci. 47, 145 147 (1967). Experiments with four different soils showed that Chang's method was simplest and quickest for routine determinations without requiring expensive equipment. (Soil and Fertilizers, 1967.) 100. J. H. Schmertmann. Static penetrometers for soil exploration. Civil Engng ASCE, 71-73 (June 1967). Research at the University of Florida indicates that the static cone penetration test offers a useful method for soil exploration. One type of static cone penetration equipment evaluated, of Dutch make, provides data on soil bearing capacity and friction. This information can then be used to identify the type of soil penetrated, without taking borings. A Swedish-made cone penetrometer was also evaluated. Although it does not have the capacity of the Dutch instrument, it does oiler a good method for shallow explorations. Cost of soil investigations with these instruments is competitive with standard penetration test investigations. (Author's summary.) 101. E. T. Selig. Soil compaction study, Volume I. Introduction and results of initial phases. Res. Inst., Chicago. 196 pp. (March 1967). A study has been undertaken to determine: the desired characteristics of compacted soils, the best method for measurement and specification of proper compaction, and the effectiveness of various ways of achieving compaction. This report is Volume I of a series of f n a l reports presenting the results of the study. The research was divided into four basic phases: field pilot studies, laboratory studies, field test program, and data reduction and analysis. This volume covers the field pilot and the laboratory studies. The latter includes: evaluation and calibration of portable nuclear soil moisture-density gages, development of automated penetrometer-plate-CBR apparatus, evaluation of cone penetrometer characteristics, classification of the subgrade soils and base course materials,