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6. The rolling tyre under load
68
ABSTRACTS provision for air venting and considerable space, sags and runs through excess paint may occur, bubbles or dirt on the bath surface can mar the finish, and solvent refluxing can remove paint from unventilated areas. S.A.E. recommendations concerning design to minimize corrosion are summarized. These include avoidance of ledges, flanges and pockets, sealing of joints, use of open construction, provision of adequate drainage and ventilation, and avoidance of dissimilar metals in contact. In tests of the 1960 Ford Falcon, it was found that foam fillings for sills tended to form random voids and shrink away from the sills to provide conditions favouring corrosion. Weld-through primers were costly and required special facilities. Sacrificially-coated steels, of which galvanized steel was l~est known and least costly, were therefore investigated. Laboratory tests, proving-ground tests, and examinations of used cars have shown that galvanized steel gives generally good protection, though additional protection in the form of zinc-rich primer has been necessary in some body areas. Electro-coating of paint ensures a uniform coating on all surfaces in contact with the paint bath, has given performance equal to or better than galvanized steel, may protect interior surfaces for ten years or more, and overcomes the problems associated with welding and finishing of surfaces treated by galvanizing or zinc-rich primer. Methods by which road authorities and car owners can help reduce vehicle corrosion conclude the paper. [M.I.R.A.]
5.
Clumce~or, W. J. and Korayern, A. Y. Mechanical energy balance for a volume element of soil during strain. A.S.A.E. Transactions, Vol. 8, No. 3, 1965. Two hypotheses have been advanced relating volume strain of soils to change in stress state. Soehne stated that soil porosity is a faxnction of the major principal stress, while Vanden Berg et al. related bulk density to mean normal stress. Other studies have indicated, however, that the shearing strain which may accompany volumetric strain has an influence on the stressporosity relationship. In this study, relations among stress state shearing strain, and porosity were investigated, and analyses were made of the distribution of the mechanical energy put into the soil during strain. [Author's Summary.]
6.
Clack, S. K. The rolling tyre under load. S.A.E. Paper, Mid-Year Meeting, May 17-21, 1965, p. 9. Methods are presented for calculating the dynamic contact-patch areas of an elastically supported cylindrical shell used to model the dynamic rolling of a loaded pneumatic tyre. These areas are shown to be influenced considerably by rolling velocity, the constructional parameters of the tyre and its viscous-loss characteristics. A generalized cylindrical shell under arbitrary loads is first considered, and force-equilibrium equations are written for the element of cylindrical-shell surface. Equilibrium equations are adapted for the specific case of a rather narrow cylindrical shell having no variation of loading in the lateral direction and an equation is given which represents the deflection of a cylindrical shell against a frictionless load, so that only radial pressures exist. This equation is adapted to include most of the properties of a real tyre by adjusting the radial-pressure term for various tyre effects and including uniform internal- and externalpressure-loading terms, inertia terms, etc. An equation is presented which expresses tr, otion of the cylindrical shell, and steady-state solutions are considered. Dynamic pressure distributions within contact-patch areas are obtained analytically, and the techniques involved are described. The shell is used as a basis for calculating the load-carrying and drag properties of pneumatic tyres, so that various tyre parameters may be approximately obtained. Diagrams illustrate, e.g. contact-patch length and position, vertical load, drag force, and maximum contact pressure as a function of speed. With the equations discussed, many of the important parameters for a tyre rolling in a straight line under constantvelocity conditions may be calculated. The form of loss law employed is vital, since this determines almost entirely the general form of the drag forces generated, and dictates to some extent the nature of the contact-patch shift as velocity increases. [M.I.R.A.]
7.
Cooney, C. E. Design and application of universal joints for off-highway vehicles. S.A.E. Paper, Farm, Construction, and Industr. Machinery Meeting, September 13-16, 1965, p. 11. The paper discusses and illustrates solutions to universal-joint problems arising in vehicle design. These problems include the significance and obtainment of the duty cycle for universal-joint components, and the determination of trunnion bending stresses, bearing life, critical speed, maximum-permissible dynamic unbalance, and torsional dynamic characteristics; the fatigue life of associated splined sections and propeller-shaft tubing is examined. A numerical example is presented of the selection of driveline components for a typical vehicle. [M.I.R.A.]
ABSTRACTS provision for air venting and considerable space, sags and runs through excess paint may occur, bubbles or dirt on the bath surface can mar the finish, and solvent refluxing can remove paint from unventilated areas. S.A.E. recommendations concerning design to minimize corrosion are summarized. These include avoidance of ledges, flanges and pockets, sealing of joints, use of open construction, provision of adequate drainage and ventilation, and avoidance of dissimilar metals in contact. In tests of the 1960 Ford Falcon, it was found that foam fillings for sills tended to form random voids and shrink away from the sills to provide conditions favouring corrosion. Weld-through primers were costly and required special facilities. Sacrificially-coated steels, of which galvanized steel was l~est known and least costly, were therefore investigated. Laboratory tests, proving-ground tests, and examinations of used cars have shown that galvanized steel gives generally good protection, though additional protection in the form of zinc-rich primer has been necessary in some body areas. Electro-coating of paint ensures a uniform coating on all surfaces in contact with the paint bath, has given performance equal to or better than galvanized steel, may protect interior surfaces for ten years or more, and overcomes the problems associated with welding and finishing of surfaces treated by galvanizing or zinc-rich primer. Methods by which road authorities and car owners can help reduce vehicle corrosion conclude the paper. [M.I.R.A.]
5.
Clumce~or, W. J. and Korayern, A. Y. Mechanical energy balance for a volume element of soil during strain. A.S.A.E. Transactions, Vol. 8, No. 3, 1965. Two hypotheses have been advanced relating volume strain of soils to change in stress state. Soehne stated that soil porosity is a faxnction of the major principal stress, while Vanden Berg et al. related bulk density to mean normal stress. Other studies have indicated, however, that the shearing strain which may accompany volumetric strain has an influence on the stressporosity relationship. In this study, relations among stress state shearing strain, and porosity were investigated, and analyses were made of the distribution of the mechanical energy put into the soil during strain. [Author's Summary.]
6.
Clack, S. K. The rolling tyre under load. S.A.E. Paper, Mid-Year Meeting, May 17-21, 1965, p. 9. Methods are presented for calculating the dynamic contact-patch areas of an elastically supported cylindrical shell used to model the dynamic rolling of a loaded pneumatic tyre. These areas are shown to be influenced considerably by rolling velocity, the constructional parameters of the tyre and its viscous-loss characteristics. A generalized cylindrical shell under arbitrary loads is first considered, and force-equilibrium equations are written for the element of cylindrical-shell surface. Equilibrium equations are adapted for the specific case of a rather narrow cylindrical shell having no variation of loading in the lateral direction and an equation is given which represents the deflection of a cylindrical shell against a frictionless load, so that only radial pressures exist. This equation is adapted to include most of the properties of a real tyre by adjusting the radial-pressure term for various tyre effects and including uniform internal- and externalpressure-loading terms, inertia terms, etc. An equation is presented which expresses tr, otion of the cylindrical shell, and steady-state solutions are considered. Dynamic pressure distributions within contact-patch areas are obtained analytically, and the techniques involved are described. The shell is used as a basis for calculating the load-carrying and drag properties of pneumatic tyres, so that various tyre parameters may be approximately obtained. Diagrams illustrate, e.g. contact-patch length and position, vertical load, drag force, and maximum contact pressure as a function of speed. With the equations discussed, many of the important parameters for a tyre rolling in a straight line under constantvelocity conditions may be calculated. The form of loss law employed is vital, since this determines almost entirely the general form of the drag forces generated, and dictates to some extent the nature of the contact-patch shift as velocity increases. [M.I.R.A.]
7.
Cooney, C. E. Design and application of universal joints for off-highway vehicles. S.A.E. Paper, Farm, Construction, and Industr. Machinery Meeting, September 13-16, 1965, p. 11. The paper discusses and illustrates solutions to universal-joint problems arising in vehicle design. These problems include the significance and obtainment of the duty cycle for universal-joint components, and the determination of trunnion bending stresses, bearing life, critical speed, maximum-permissible dynamic unbalance, and torsional dynamic characteristics; the fatigue life of associated splined sections and propeller-shaft tubing is examined. A numerical example is presented of the selection of driveline components for a typical vehicle. [M.I.R.A.]