- Email: [email protected]
14. An investigation of thixotropy in highly plastic clays
102
ABSTRACTS
11.
. I . L . McRae. Development of a Formula for Towing Resistance for a Wheel in Soft Soil. Army Engineer Waterways Experiment Station, Vicksburg, Miss. Mobility and Environmental Div. The Buckingham pi theorem approach to dimensional analysis is used. Analyses are made for a rigid wheel and pneumatic-tired wheels. (U.S. Govt. Res. Dev. Reports.)
12.
D. W. Rowley. Control of Farm Tractor Intake and Exhaust Noise. S.A.E. Paper No. 660598, Farm, Construction and lndustr. Machinery Meeting, 12-15 September 1966, 14 p. Octave-band analysis of the noise measured at the driver's ear on a large tractor operated at full power shows that the sound-pressure level exceeds the California 95-dB contour for industrial noise in a 107-dB peak in the second octave. Since this peak is caused by exhaust, or possibly intake, noise, the 95-dB requirement could be met by installing a slightly better silencer. It would be very difficult to reach the 85-dB contour recommended by many medical authorities because of noises other than exhaust. Exhaust was found to be the major noise source, followed by fan, mechanical, and intake noise. Measurements on a small tractor with horizontal exhaust system showed greater overall noise levels, close to and even exceeding the 95-dB contour in many places, and greater intake noise in comparison with the larger tractor. The creation and control of exhaust and intake noise are examined. Octave-band data for the exhaust of the large tractor with and without silencer shows that the silencer performed excellently in the middle and upper octaves. The cross-sectional area of a silencer determines the amount of noise attenuation possible, while the internal design and length determines the frequencies at which attenuation occurs. The silencing properties of various types of air-cleaner are discussed. Sound-pressure level is plotted against octave band for an open-pipe intake and an intake with aircleaner. Most air-cleaners are fairly good silencers, the oil-bath type being more effective than most dry types. The effects of silencer and air-cleaner location on exhaust noise are examined, and it is shown, e.g. that, for the small tractor with 66 in. long horizontal exhaust system containing arL 18 in. silencer of simple design, an exhaust pipe of 22 in. and tail pipe of 26 in. would give the best results, based on loudness rating. The effects of intake and exhaust systems on engine performance can be reasonably well predicted from inlet restriction and back-pressure readings. Data showing the effect of transfer pipe length on engine h.p. and of exhaust-system tuning on h.p. output are presented. It is improbable that noise can be controlled to the California 95-dB contour on some tractors by decreasing exhaust noise only. The complete exhaust or induction system must be considered, not only the silencer or air-cleaner. An appendix deals with the acoustical charac'~eristics of induction systems as predicted by attenuation equation. (M.I.R.A.)
13.
R . D . Stoll, I. A. Ebeido and M. S. Hess. Investigations of the Quasi-Static and Dynamic Response of G r a n u l a r Soils. Columbia Univ., New York. Dept. of Civil Engineering and Engineering Mechanics. The report describes experimental studies of shock-induced sustained-amplitude stress waves in soil. A general analysis is made of wave propagation in a cylindrical bar. The mathematical model includes stress relaxation and radial inertia factors. Also included is analytical interpretation of unloading wave propagation. Unloading waves were generated experimentally by suddenly unloading a previously loaded cylindrical specimen. The analysis results in a theory which accounts for longitudinal, axial, and radial shear modes. Preliminary results are presented of experiments involving earth shock with spherical symmetry. Quasi-static isotropic compression tests and their associated problems are discussed. (U.S. Govt. Res. Dev. Reports.)
14.
M. D e e Swensen. An investigation of Thixotropy in Highly Plastic Clays. Arizonta State Univ., Tempe. This study was made to establish the effect of thixotropy on a specified clay and to determine if a means could be established where thixotropy can be predicted and then used in design. A review was made of the theories of thixotropy and how the strength increases takes place. Investigation performed by other authors were reviewed and their conclusions on the feasibility of using thixotropic strength increase in design was discussed. Two clays were used in the study. Each was prepared at three different water contents
A BSTRACTS
103
near the liquid limit. The samples were placed in two types of containers and stored under water. Shear strength is affected by changes in water content; therefore a secondary study was to determine the effectiveness of the methods used to control the water content of the stored samples. Samples were stored a maximum of 150 days. Tests were made at specified times during this period to determine the strength increase that developed with time. It was found that the strength increase of the clays tested could be defined by an equation. The accuracy of the equation was not determined for all water contents but only those used in the study. (Author's Summary.) 15. P. A. Taylor and R. Birtwisfle. Experimental Studies of Force Systems on Steered Agricultural Tyres. CSIRO, Highett, Victoria, Australia. (Inst. Mech. Eng. Auto. Div.) The authors report the experimental determination of the force systems acting on free-rolling 7"50-16 agricultural tyres, measured with a six-component suspension of the test wheel. Multivariate techniques were used involving five variables: slip-angle, camber, vertical load, tyre pattern and land or furrow operation. The results are presented as three-force and three-moment components. Other methods of representation are discussed briefly. Although the side or cornering force depends on many factors, particularly the soil surface, and is therefore difficult to predict, it is suggested that the draught force (i.e. resistance in the direction of motion) can be expressed as a function of slip for all surfaces, (Author's Summary.) These abstracts have been collected by P. E. R. Cook of the Department of Agricultural Engineering, The University of Newcastle upon Tyne. The National Institute of Agricultural Engineering, Silsoe, Bedford, has now ceased publication of "Agricultural and Horticultural Engineering Abstracts". It has thus become difficult to obtain abstracts giving a comprehensive cover of this field. The Automobile Engineering Abstracts are taken from the Monthly Summaries by the Motor Industry Research Association, Lindley, Warwickshire. The following is a list of the publications searched in addition with a view to covering the remaining large fields of Civil and Mechanical Engineering. The relevant and important field of Military Engineering is not covered because the abstractor has no access to it. (1) (2) (3) (4) (5) (6) ~7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21)
). Soil Mech. Foundations Divn.--American Soc. Civil Eng., New York. G~otechnique--Inst. Civil Eng., London. Road Abstracts--Road Research Lab., West Drayton, Middlesex. Engineering--36 Bedford Street, London. The Engineer--28 Essex Street, London. The Overseas Engineer--Bowling Green Lane, London. The Charted Mech. Engr.--Inst. Mech. Eng., London. Mechanical Engineering--Am. Soc. Mech. Engnr., New York. Journal of App. Mech.--Am. Soc. Mech. Engnr., New York. Applied Mechanics Review--Am. Soc. Mech. Engineers, New York. Agricultural Engineering--Am. Soc. Agric. Engnr., Michigan, U.S.A. J. Agric. Eng. Res.--N.I.A.E., Bedford. U.S. Govt. Res. Dev. Repts.--Dept. of Commerce, Springfield, Va. Technical Translations--U.S. Dept. of Comm., Springfield, Va. Civil Engineering--Buckingham Street, London. Excavating Engineer--Barrington, Illinois. Roads and Roads Const.--Victoria Street, London. Civil Engineering--Am. Soc. Civil Engnrs., New York. Automotive Design Engineering--Rowse Muir Publications, London. Soil Science Proceedings--Soil Science Soc. of Am., Ohio. Materials Research and Standards--Am. Soc. for Testing and Materials, Philadelphia.
ABSTRACTS
11.
. I . L . McRae. Development of a Formula for Towing Resistance for a Wheel in Soft Soil. Army Engineer Waterways Experiment Station, Vicksburg, Miss. Mobility and Environmental Div. The Buckingham pi theorem approach to dimensional analysis is used. Analyses are made for a rigid wheel and pneumatic-tired wheels. (U.S. Govt. Res. Dev. Reports.)
12.
D. W. Rowley. Control of Farm Tractor Intake and Exhaust Noise. S.A.E. Paper No. 660598, Farm, Construction and lndustr. Machinery Meeting, 12-15 September 1966, 14 p. Octave-band analysis of the noise measured at the driver's ear on a large tractor operated at full power shows that the sound-pressure level exceeds the California 95-dB contour for industrial noise in a 107-dB peak in the second octave. Since this peak is caused by exhaust, or possibly intake, noise, the 95-dB requirement could be met by installing a slightly better silencer. It would be very difficult to reach the 85-dB contour recommended by many medical authorities because of noises other than exhaust. Exhaust was found to be the major noise source, followed by fan, mechanical, and intake noise. Measurements on a small tractor with horizontal exhaust system showed greater overall noise levels, close to and even exceeding the 95-dB contour in many places, and greater intake noise in comparison with the larger tractor. The creation and control of exhaust and intake noise are examined. Octave-band data for the exhaust of the large tractor with and without silencer shows that the silencer performed excellently in the middle and upper octaves. The cross-sectional area of a silencer determines the amount of noise attenuation possible, while the internal design and length determines the frequencies at which attenuation occurs. The silencing properties of various types of air-cleaner are discussed. Sound-pressure level is plotted against octave band for an open-pipe intake and an intake with aircleaner. Most air-cleaners are fairly good silencers, the oil-bath type being more effective than most dry types. The effects of silencer and air-cleaner location on exhaust noise are examined, and it is shown, e.g. that, for the small tractor with 66 in. long horizontal exhaust system containing arL 18 in. silencer of simple design, an exhaust pipe of 22 in. and tail pipe of 26 in. would give the best results, based on loudness rating. The effects of intake and exhaust systems on engine performance can be reasonably well predicted from inlet restriction and back-pressure readings. Data showing the effect of transfer pipe length on engine h.p. and of exhaust-system tuning on h.p. output are presented. It is improbable that noise can be controlled to the California 95-dB contour on some tractors by decreasing exhaust noise only. The complete exhaust or induction system must be considered, not only the silencer or air-cleaner. An appendix deals with the acoustical charac'~eristics of induction systems as predicted by attenuation equation. (M.I.R.A.)
13.
R . D . Stoll, I. A. Ebeido and M. S. Hess. Investigations of the Quasi-Static and Dynamic Response of G r a n u l a r Soils. Columbia Univ., New York. Dept. of Civil Engineering and Engineering Mechanics. The report describes experimental studies of shock-induced sustained-amplitude stress waves in soil. A general analysis is made of wave propagation in a cylindrical bar. The mathematical model includes stress relaxation and radial inertia factors. Also included is analytical interpretation of unloading wave propagation. Unloading waves were generated experimentally by suddenly unloading a previously loaded cylindrical specimen. The analysis results in a theory which accounts for longitudinal, axial, and radial shear modes. Preliminary results are presented of experiments involving earth shock with spherical symmetry. Quasi-static isotropic compression tests and their associated problems are discussed. (U.S. Govt. Res. Dev. Reports.)
14.
M. D e e Swensen. An investigation of Thixotropy in Highly Plastic Clays. Arizonta State Univ., Tempe. This study was made to establish the effect of thixotropy on a specified clay and to determine if a means could be established where thixotropy can be predicted and then used in design. A review was made of the theories of thixotropy and how the strength increases takes place. Investigation performed by other authors were reviewed and their conclusions on the feasibility of using thixotropic strength increase in design was discussed. Two clays were used in the study. Each was prepared at three different water contents
A BSTRACTS
103
near the liquid limit. The samples were placed in two types of containers and stored under water. Shear strength is affected by changes in water content; therefore a secondary study was to determine the effectiveness of the methods used to control the water content of the stored samples. Samples were stored a maximum of 150 days. Tests were made at specified times during this period to determine the strength increase that developed with time. It was found that the strength increase of the clays tested could be defined by an equation. The accuracy of the equation was not determined for all water contents but only those used in the study. (Author's Summary.) 15. P. A. Taylor and R. Birtwisfle. Experimental Studies of Force Systems on Steered Agricultural Tyres. CSIRO, Highett, Victoria, Australia. (Inst. Mech. Eng. Auto. Div.) The authors report the experimental determination of the force systems acting on free-rolling 7"50-16 agricultural tyres, measured with a six-component suspension of the test wheel. Multivariate techniques were used involving five variables: slip-angle, camber, vertical load, tyre pattern and land or furrow operation. The results are presented as three-force and three-moment components. Other methods of representation are discussed briefly. Although the side or cornering force depends on many factors, particularly the soil surface, and is therefore difficult to predict, it is suggested that the draught force (i.e. resistance in the direction of motion) can be expressed as a function of slip for all surfaces, (Author's Summary.) These abstracts have been collected by P. E. R. Cook of the Department of Agricultural Engineering, The University of Newcastle upon Tyne. The National Institute of Agricultural Engineering, Silsoe, Bedford, has now ceased publication of "Agricultural and Horticultural Engineering Abstracts". It has thus become difficult to obtain abstracts giving a comprehensive cover of this field. The Automobile Engineering Abstracts are taken from the Monthly Summaries by the Motor Industry Research Association, Lindley, Warwickshire. The following is a list of the publications searched in addition with a view to covering the remaining large fields of Civil and Mechanical Engineering. The relevant and important field of Military Engineering is not covered because the abstractor has no access to it. (1) (2) (3) (4) (5) (6) ~7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21)
). Soil Mech. Foundations Divn.--American Soc. Civil Eng., New York. G~otechnique--Inst. Civil Eng., London. Road Abstracts--Road Research Lab., West Drayton, Middlesex. Engineering--36 Bedford Street, London. The Engineer--28 Essex Street, London. The Overseas Engineer--Bowling Green Lane, London. The Charted Mech. Engr.--Inst. Mech. Eng., London. Mechanical Engineering--Am. Soc. Mech. Engnr., New York. Journal of App. Mech.--Am. Soc. Mech. Engnr., New York. Applied Mechanics Review--Am. Soc. Mech. Engineers, New York. Agricultural Engineering--Am. Soc. Agric. Engnr., Michigan, U.S.A. J. Agric. Eng. Res.--N.I.A.E., Bedford. U.S. Govt. Res. Dev. Repts.--Dept. of Commerce, Springfield, Va. Technical Translations--U.S. Dept. of Comm., Springfield, Va. Civil Engineering--Buckingham Street, London. Excavating Engineer--Barrington, Illinois. Roads and Roads Const.--Victoria Street, London. Civil Engineering--Am. Soc. Civil Engnrs., New York. Automotive Design Engineering--Rowse Muir Publications, London. Soil Science Proceedings--Soil Science Soc. of Am., Ohio. Materials Research and Standards--Am. Soc. for Testing and Materials, Philadelphia.