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Elastic transmission joints
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ABSTRACTS independently or by means of a stress control device which is a mechanical-hydraulic analog of an octahedral plane in the principal stress space. The three principal strains are measured, together with an independent measurement of the volume change of the soil sample. The behaviour of a medium dense Ottawa sand in an axial compression test at constant octahedral stress in the equipment is compared with that of the same material in a conventional triaxial apparatus. (Author's Summary). B . I . Kogan and G. M. Satsuk. Solution of Contact Problems in the Mechanics of Nonhomogeneous Foundations by Plate Analogy. Soil Mechanics and Foundation Engineering No. 2, 79-85, Mar./Apr. 1964. (Translation of Osnovaniya Fundamenty i Mekhanika Gruntov No. 2, 6-9, Mar./Apr. 1964). An analog is used to find the stresses induced in an elastic subsoil (which may be nonhomogeneous) by the application of load from a foundation. The model is a thin plate whose thickness is made inversely proportional to the cube root of Young's modulus for the foundation zone represented. Thus, a rigid footing is represented by an area cut out of the plate in the crosssectional shape of the footing. The plate is bent about an axis representing the line of action of the resultant load, and if plane strain conditions are assumed, the bending stresses on the surface of the plate are analogous to the direct stresses within the foundation. In previous (Russian) papers quoted, bending stresses were obtained by differentiation of measured deflexions. This paper describes the use of strain gages. Results are given for a centrally-loaded strip footing on a homogeneous foundation which compare quite well with the theoretical result. As a practical application, stresses beneath the irregularly shaped Kiev hydropower station are given. Although strictly only exact when Poisson's ratio is zero (in both foundation and plate), this intriguing analogy will no doubt become more widely used. (App. Mech. Rev.). I.K. Lee. Stress-Dilatancy Performance of Feldspur, J. Soil Mech. Fdns Div. Am. Soc. cir. Engrs 92, SM 2, 79 103, Mar. 1966. Drained compressions test on normally consolidated and over-consolidated samples of feldspar (d-h4 in, lateral pressure: 10-95 lb/in", overconsolidation pressure 0-120 lb/in 2, frictionless ends) were conducted to check stress-dilatancy theory (Rowe) for high value of true friction angle between grains (q0~ -37:). Moreover, experimental values of Coulomb q0 at critical void ratio (~cv) are compared with theoretical values, using Caquot, Bishop and Home theories. Principal conclusions of the author are: 1. Stress-dilatancy relationship is closely obeyed by feldspar in pre-peak stress-ratio range; reloading of samples previously subjected to small strains showed that the relationship again is obeyed, but agreement is not as precise as for results on less frictional, rotund particulate samples. 2. ~cv values predicted by Horne agree closely with experimental values for four cohesionless specimens (tp~ 7-37~). (Appl. Mech. Rev.). W. A. Lewis. Full-scale Studies of the Performance of Plant in the Compaction of Soils and Granular Base Materials. hist. Mech. Engrs. Auto. Div. Advance Copy, January 23, 1967, 13 pp. Soil compaction, which is vitally important in modern road-making, has been extensively studied to determine optimum compaction plant and operating methods. A special building housing five soil bays and two bays of granular, road-base materials permits testing of the largest compaction machines. Compaction tests on five different soils are reported for pneumatic tyred, smooth-wheeled, grid and sheepsfoot rollers, rammers and three types of vibrating roller. Studies have also been made of: (1) factors affecting compaction-machine performance, e.g., roller diameter, wheel load, tyre inflation pressure and frequency of vibration ; (2) the compaction of granular, road-base materials. (M.I.R.A.). ,I. Morion. Elastic Transmission Joints, lng. Auto., May, 1964, 37, No. 5, pp. 267 284 incl. discussion; M.I.R.A. Translation No. 19/67, 17 pp. Whereas mechanical transmission joints are generally considered almost entirely from the aspect of kinematics, elastic joints have a dynamic role also. In connection with joint kinematics, it is pointed out that, unlike a mechanical joint, an elastic joint can accommodate relative axial, radial, polar and angular misalignments between driving and driven shafts, and the reactions to misalignment are independent of the applied torque. Elastic couplings, therefore, are concluded to offer especial advantages where small relative displacements, often due to assembly tolerances, accidental displacements of elements of the vehicle elements, etc., exist; they also eliminate the need for lubrication and sealing. In connection with dynamic aspect of elastic couplings, a detailed analysis is given of their action under the influence of single torque peaks and pulsating torques. With a well-applied coupling, twisting of the coupling elements can transform an irregular motion into an almost completely regular rotation, but care must be taken that the torsional fatigue stresses do not affect excessively the life of the coupling. Rubber compounds with high damping properties tend
ABSTRACTS
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to have the greatest permanent deformation and temperature rise in operation. To enable the coupling to operate both at low speeds, when considerable flexibility is required, and at higher speeds and torques at which the elements would otherwise be too soft, variable-stiffness couplings have been developed. Examples are then given of various types of elastic couplings. These include components in which the rubber operates in shear in directions perpendicular to the axis of rotation, e.g., elastic clutch centres and transmission couplings in the form of cylindrical sleeves, those working in compression, such as the wheel-hub couplings in some Simca and Fiat cars, couplings working in shear and compression and/or tension, e.g., the Neidhart designs, and variable-flexibqity designs such as those in which initial deformation is taken by rubber in shear and greater deformation by rubber in compression. Flector-type couplings are sesentially elastic discs attached by alternate bolts to the driving and driven shafts. Examples described include Brampton discs, Flexed and Jurid rings, and Giubo and Periflex Stromag couplings. Mechanical couplings in which bearings are replaced by elastic bushes are exemplified by the B.M.C. front-wheel-drive inboard joints and the Metalastik link-type coupling. Mixed systems embodying both elastic and mechanical couplings are sometimes found in propeller-shaft systems. The discussion covers questions of behaviour of rubber at low temperatures and the maximum angularity obtainable with elastic couplings. (M.I.R.A.). A. Mukhopadhay. On the Solution of Problems of Dynamic Plane Elasticity for Sandy Soil, J. Sci. Engng Res., India 9, 2, 213-221, July 1965. In this paper, the method of complex variables has been applied to the solution of problems of dynamic plane elasticity for sandy soil of the type considered by Weiskoff (Journal o f the Franklin Institute 289, 445465, 1945). General expressions have been obtained for the stresses and displacements due to a moving disturbance in such a soil, and the stresses and displacements in sandy soil of this type have been obtained for three particular cases--a moving Griffith crack, a moving dislocation, and a parabolic punch moving along the boundary of a half-plane. (Author's Summary). E. M, Perlei. The Effects of Vibrations on the Forces of External Friction of Soils. Soil Mech. Fndn Engng No. 3, 147-152, May/June 1964. (Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov 1, 3, 5-8, Mar. 1964). Article deals with laboratory investigations related to a bar forced through a soil mass, the bar being simultaneously subjected to longitudinal vibrations. Various soil types (dry and moist sand, soft sandy loam), vibration parameters, normal pressures on soil, and bar pulling forces were adopted. Experiments showed that strength characteristics due to bar-soil friction are very different for statical and vibrating pull of the bar. In dry sand, resistance values most nearly correspond to dry friction, but the frictional coefficients has much less value in the case of vibrating pull as compared to statical case. In moist sand and soft sandy loam, the variation of friction characteristics during vibration is not far from that corresponding to viscous friction. Exposed data and statements, inspite of the small experiment scale used, furnish valuable information for complex practical processes such as dynamical pile driving. (Appl. Mech. Rev.). G . P . Raymond. The Bearing Capacity of Large Footings and Embankments on Clay, Geotechnique 17, No. I, 1967. Many earth dams and highway embankments are built on soft clay deposits. The materials of which these dams and embankments are built are often brittle enough for tension cracks to develop throughout their full height. Alternatively they are constructed of granular material. Since a slip circle drawn through the foundation will be almost vertical through the granular mass, it seems reasonable, as a first approximation, to ignore the strength contributed by the granular mass. The paper derives a solution for the bearing capacity of a uniformly-loaded flexible surfacefooting on a frictionless soil exhibiting a linear change in strength with depth. The application of the solution to the stability of an embankment or dam is given. In addition, the effect of footing shape, depth to which the base has been buried below the surface and the effect of an upper desiccated crust is discussed. Seven published case records are analysed and reasonable agreement is found between the records and the proposed solution. (Author's Summary). A. S. Reddy and R. J. Srinivasan. Bearing Capacity of Footings on Layered Clays, J. Soil Mech. Fdns Div. Am. Soc. civ.Engrs, Vol. 93. No. SM2, Proc. Paper, 5141, March, 1967, pp. 83-99. An analysis of the bearing capacily factors, Are for strip footings on anisotropic two-layer cohesive soils is reported. Numerical results in nondimensional form are presented for two cases : (1) A system of two layers having constant shear strength with depth in each layer, and (2) a single layer in which the shear strength varies linearly with depth. (Author's Summary). O. Ya. Shekhter and O. E. Prikhodehenko. Stress and Displacement Distributions in an Elastic Layer Acted on by Internal Point Forces, Soil Mech. Fdn Engng, No. 5,275-279, Sept./Oct. 1964.
28,
29.
30.
31.
ABSTRACTS independently or by means of a stress control device which is a mechanical-hydraulic analog of an octahedral plane in the principal stress space. The three principal strains are measured, together with an independent measurement of the volume change of the soil sample. The behaviour of a medium dense Ottawa sand in an axial compression test at constant octahedral stress in the equipment is compared with that of the same material in a conventional triaxial apparatus. (Author's Summary). B . I . Kogan and G. M. Satsuk. Solution of Contact Problems in the Mechanics of Nonhomogeneous Foundations by Plate Analogy. Soil Mechanics and Foundation Engineering No. 2, 79-85, Mar./Apr. 1964. (Translation of Osnovaniya Fundamenty i Mekhanika Gruntov No. 2, 6-9, Mar./Apr. 1964). An analog is used to find the stresses induced in an elastic subsoil (which may be nonhomogeneous) by the application of load from a foundation. The model is a thin plate whose thickness is made inversely proportional to the cube root of Young's modulus for the foundation zone represented. Thus, a rigid footing is represented by an area cut out of the plate in the crosssectional shape of the footing. The plate is bent about an axis representing the line of action of the resultant load, and if plane strain conditions are assumed, the bending stresses on the surface of the plate are analogous to the direct stresses within the foundation. In previous (Russian) papers quoted, bending stresses were obtained by differentiation of measured deflexions. This paper describes the use of strain gages. Results are given for a centrally-loaded strip footing on a homogeneous foundation which compare quite well with the theoretical result. As a practical application, stresses beneath the irregularly shaped Kiev hydropower station are given. Although strictly only exact when Poisson's ratio is zero (in both foundation and plate), this intriguing analogy will no doubt become more widely used. (App. Mech. Rev.). I.K. Lee. Stress-Dilatancy Performance of Feldspur, J. Soil Mech. Fdns Div. Am. Soc. cir. Engrs 92, SM 2, 79 103, Mar. 1966. Drained compressions test on normally consolidated and over-consolidated samples of feldspar (d-h4 in, lateral pressure: 10-95 lb/in", overconsolidation pressure 0-120 lb/in 2, frictionless ends) were conducted to check stress-dilatancy theory (Rowe) for high value of true friction angle between grains (q0~ -37:). Moreover, experimental values of Coulomb q0 at critical void ratio (~cv) are compared with theoretical values, using Caquot, Bishop and Home theories. Principal conclusions of the author are: 1. Stress-dilatancy relationship is closely obeyed by feldspar in pre-peak stress-ratio range; reloading of samples previously subjected to small strains showed that the relationship again is obeyed, but agreement is not as precise as for results on less frictional, rotund particulate samples. 2. ~cv values predicted by Horne agree closely with experimental values for four cohesionless specimens (tp~ 7-37~). (Appl. Mech. Rev.). W. A. Lewis. Full-scale Studies of the Performance of Plant in the Compaction of Soils and Granular Base Materials. hist. Mech. Engrs. Auto. Div. Advance Copy, January 23, 1967, 13 pp. Soil compaction, which is vitally important in modern road-making, has been extensively studied to determine optimum compaction plant and operating methods. A special building housing five soil bays and two bays of granular, road-base materials permits testing of the largest compaction machines. Compaction tests on five different soils are reported for pneumatic tyred, smooth-wheeled, grid and sheepsfoot rollers, rammers and three types of vibrating roller. Studies have also been made of: (1) factors affecting compaction-machine performance, e.g., roller diameter, wheel load, tyre inflation pressure and frequency of vibration ; (2) the compaction of granular, road-base materials. (M.I.R.A.). ,I. Morion. Elastic Transmission Joints, lng. Auto., May, 1964, 37, No. 5, pp. 267 284 incl. discussion; M.I.R.A. Translation No. 19/67, 17 pp. Whereas mechanical transmission joints are generally considered almost entirely from the aspect of kinematics, elastic joints have a dynamic role also. In connection with joint kinematics, it is pointed out that, unlike a mechanical joint, an elastic joint can accommodate relative axial, radial, polar and angular misalignments between driving and driven shafts, and the reactions to misalignment are independent of the applied torque. Elastic couplings, therefore, are concluded to offer especial advantages where small relative displacements, often due to assembly tolerances, accidental displacements of elements of the vehicle elements, etc., exist; they also eliminate the need for lubrication and sealing. In connection with dynamic aspect of elastic couplings, a detailed analysis is given of their action under the influence of single torque peaks and pulsating torques. With a well-applied coupling, twisting of the coupling elements can transform an irregular motion into an almost completely regular rotation, but care must be taken that the torsional fatigue stresses do not affect excessively the life of the coupling. Rubber compounds with high damping properties tend
ABSTRACTS
32.
33.
34.
35.
36.
77
to have the greatest permanent deformation and temperature rise in operation. To enable the coupling to operate both at low speeds, when considerable flexibility is required, and at higher speeds and torques at which the elements would otherwise be too soft, variable-stiffness couplings have been developed. Examples are then given of various types of elastic couplings. These include components in which the rubber operates in shear in directions perpendicular to the axis of rotation, e.g., elastic clutch centres and transmission couplings in the form of cylindrical sleeves, those working in compression, such as the wheel-hub couplings in some Simca and Fiat cars, couplings working in shear and compression and/or tension, e.g., the Neidhart designs, and variable-flexibqity designs such as those in which initial deformation is taken by rubber in shear and greater deformation by rubber in compression. Flector-type couplings are sesentially elastic discs attached by alternate bolts to the driving and driven shafts. Examples described include Brampton discs, Flexed and Jurid rings, and Giubo and Periflex Stromag couplings. Mechanical couplings in which bearings are replaced by elastic bushes are exemplified by the B.M.C. front-wheel-drive inboard joints and the Metalastik link-type coupling. Mixed systems embodying both elastic and mechanical couplings are sometimes found in propeller-shaft systems. The discussion covers questions of behaviour of rubber at low temperatures and the maximum angularity obtainable with elastic couplings. (M.I.R.A.). A. Mukhopadhay. On the Solution of Problems of Dynamic Plane Elasticity for Sandy Soil, J. Sci. Engng Res., India 9, 2, 213-221, July 1965. In this paper, the method of complex variables has been applied to the solution of problems of dynamic plane elasticity for sandy soil of the type considered by Weiskoff (Journal o f the Franklin Institute 289, 445465, 1945). General expressions have been obtained for the stresses and displacements due to a moving disturbance in such a soil, and the stresses and displacements in sandy soil of this type have been obtained for three particular cases--a moving Griffith crack, a moving dislocation, and a parabolic punch moving along the boundary of a half-plane. (Author's Summary). E. M, Perlei. The Effects of Vibrations on the Forces of External Friction of Soils. Soil Mech. Fndn Engng No. 3, 147-152, May/June 1964. (Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov 1, 3, 5-8, Mar. 1964). Article deals with laboratory investigations related to a bar forced through a soil mass, the bar being simultaneously subjected to longitudinal vibrations. Various soil types (dry and moist sand, soft sandy loam), vibration parameters, normal pressures on soil, and bar pulling forces were adopted. Experiments showed that strength characteristics due to bar-soil friction are very different for statical and vibrating pull of the bar. In dry sand, resistance values most nearly correspond to dry friction, but the frictional coefficients has much less value in the case of vibrating pull as compared to statical case. In moist sand and soft sandy loam, the variation of friction characteristics during vibration is not far from that corresponding to viscous friction. Exposed data and statements, inspite of the small experiment scale used, furnish valuable information for complex practical processes such as dynamical pile driving. (Appl. Mech. Rev.). G . P . Raymond. The Bearing Capacity of Large Footings and Embankments on Clay, Geotechnique 17, No. I, 1967. Many earth dams and highway embankments are built on soft clay deposits. The materials of which these dams and embankments are built are often brittle enough for tension cracks to develop throughout their full height. Alternatively they are constructed of granular material. Since a slip circle drawn through the foundation will be almost vertical through the granular mass, it seems reasonable, as a first approximation, to ignore the strength contributed by the granular mass. The paper derives a solution for the bearing capacity of a uniformly-loaded flexible surfacefooting on a frictionless soil exhibiting a linear change in strength with depth. The application of the solution to the stability of an embankment or dam is given. In addition, the effect of footing shape, depth to which the base has been buried below the surface and the effect of an upper desiccated crust is discussed. Seven published case records are analysed and reasonable agreement is found between the records and the proposed solution. (Author's Summary). A. S. Reddy and R. J. Srinivasan. Bearing Capacity of Footings on Layered Clays, J. Soil Mech. Fdns Div. Am. Soc. civ.Engrs, Vol. 93. No. SM2, Proc. Paper, 5141, March, 1967, pp. 83-99. An analysis of the bearing capacily factors, Are for strip footings on anisotropic two-layer cohesive soils is reported. Numerical results in nondimensional form are presented for two cases : (1) A system of two layers having constant shear strength with depth in each layer, and (2) a single layer in which the shear strength varies linearly with depth. (Author's Summary). O. Ya. Shekhter and O. E. Prikhodehenko. Stress and Displacement Distributions in an Elastic Layer Acted on by Internal Point Forces, Soil Mech. Fdn Engng, No. 5,275-279, Sept./Oct. 1964.